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Home My WebLink AboutCO 083 B ,_,TA, ;'~ 0~' DEPART~'~.~T OF NATURAL RESOURCES DIV!SIO? OF Oil. A?[D GAS Alaska Oil and Gas Conservation Comz;ittee 3001 Porcuoine Drive Anc~.orage, Alaska 99504 ?~e: THE APPLICATION OF ATLANTIC RICHFIELD BP ALASKA, INC. , AND IKD.[BLE OIL & ,REFINING COMPAb~f for an extension of Conservation Order No. 83-B Conservation Order No. o°3-B,I Prudhoe Bay Field Prudhoe Bay Sadlerochit Oil Pool September 24, 1970 IT APPEARING THAT: 1. The Atlantic Richfield Company~ BP Alaska, Inc.~ and Humble Oil & Refining Company submitted requests dated Aucust 12 and AUgust 14, 1970 for an extension of the referenced order beyond October 12, 1970. 2. Said requests were based on the fact that the personnel who would be required to participate in a subsequent hearing are actively involved in work on the proposed Prudhoe Bay Unit Agreement~ and diversion of personnel to prepare for a hearing would delay completion of the Prudhoe Bay Unit Agreement. AND IT FURTHER APPEARING THAT: 1. Finding No. 14 of Conservation Order No. 83-B is as follows:. Unitization of the pools within the Prudhoe Bay Field would conserve natural resources, prevent waste~ and secure other benefits including that of eliminating unnecessary operations~ thereby minimizing adverse effects upon the ecology. 2. The anticipated delay in production from the Prudhoe Bay Sadlerochit Oil Pool and the resulting slowdo~m in development drilling obviate the necessity for a further hearing at this time. 3. There is no evidence that waste of oil or gas will occur or that correlative rights will be impaired if the referenced, order is extended. CONSERVATION ORDER NO. 83-B.~ September 24~ 1970 NOW, THEREFORE, IT IS ORDEP~ED that Conservation Order ~'~o. 83-B is extended through March 12, 19 71. DONE at Anchorage, Alaska, and dated Seotember 24, 1970. Concurrence~ Homer L. Burrell~ Chairman Alaska ()il and Gas Conservation Committee O. K. Gilbreth~, Jr.., i~'~.ember Alaska Oil and Gas Conservation Committee STATE OF ALASKA DEPARTMENT OF NATURAL RESOURCES D~VIS~ON OF O~L AND GAS Alaska Oil and Gas Conservation Committee 3001 Porcupine Drive Anchorage, Alaska 99504 Re: THE MOTION OF THE OIL AND GAS ) CONSERVATION COMMITTEE to hear ) ..testimony to establish pool rules ) for the Prudhoe Bay Field. ) Conservation Order No. 83-B Prudhoe Bay Field Prudhoe Bay Sadlerochit Oil Pool January 12, 1970 IT APPEARING THAT: I. The Alaska Oil and Gas Conservation Committee moved to hear testimony to establish pool rules for the Prudhoe Bay Field. 2. Notice of pub!lc heari~ng was published in the Anchorage Daily News on October 7, ~969. 3. A public hearing was held in the Sydney Laurence AUditorium, Anchorage, Alaska, on November 13 and 14, 1969. Testimony was presented in response to the motion. Affected and interested parties were heard. 4. The hearing was continued until the close of business on December 1969, and by subsequent notice published in the Anchorage Daily News on November 29, 1969, until the close of business on December 15, 1969. Additional statements were received. AND IT FURTHER APPEARING THAT: I. The Sadlerochit Formation contains very porous, fine- to medium-grained, well-sorted quartz sandstones which are not separated from each other by impermeable rocks of sufficient thickness to constitute a permeability barrier. 2. Oil is found over a wide area in the Sadlerochit Formation, an oil reservoir with an associated gas cap exists, and an oil pool should be defined. 3. The areal extent o~ the oil-bearing sands of the Sadlerochit Formation cannot be determined, but available information indicates an area where oil production can reasonably be expected. 4. The name Sadlerochit is appropriate for this oil pool. CONSERVATION ORDER NO. 83-B Page 2 January 12, 1970 5. The permeability and pressure communication in this reservoir is such that a well should drain 640 acres. 6. A distance of I,O0~ feet between wells might result in a poor drainage pattern where not more than one well is permitted on a governmental section, and a well 500 feet from a property line where ownership changes might impair correlative rights. 7. Evidence is insufficient to define the Oxytoma Formation as an oil pool, and the Oxytoma Formation is separated from the Sadlerochit Formation by 40 to 150 feet of shales, limestone, and phosphatic rocks which may constitute a permeability barrier. 8. Conventional casing and cementing procedures are unsafe if thawing occurs because thawing of the permafrost during productionmight cause sufficient subsidence and frictional drag to result in collapse of the casing within the upper 500 feet, and it is necessary t~ either prevent thawing of the adjoining permafrost or to permit movement of the surface casing. 9. Either prevention of thawing or permitting movement of the upper portion of the surface casing is safe and technologically sound; however, other methods may likewise be safe and sound, and continued surveillance by the Committee of al~ techniques will be necessary to insure maximum~ safety in future operations. ~0. To obtain the high production rates anticipated it may be necessary to produce through the tubing-casing annulus in which case any uncemented portion of the production casing below the shoe of the next shallower casing string may not give adequate protection against underground waste in the event of casing failure. II. Installation of downhole automatic shut-in valves and adequate blowout preventers might prevent an uncontrolled flow of oil or gas. 12. To properly regulate and operate the reservoir, performance must be carefully monitored and bottomhol~e pressure and gas-oil ratio test data must be obtained soon after production commences. 13. Gas is dissolved in the oil and will be produced with the oil, and the flari~ng or venting of gas may constitute waste. 14. Unitization of the pools within the Prudhoe Bay Field would conserve natural resources, prevent waste, and secure other benefits including that of eliminating unnecessary operations, thereby minimizing adverse effects upon the ecology. ~5. Application of this order to an undefined pool is not justified. CONSERVATION ORDER NO. 83-B Page 3 January 12, 1970 16. The procedures set forth in Title II AAC, Sections 2009 and 2012 are adequate for purposes of considering requests for exceptions to Title II AAC, Division 2, Chapter i or any order promulgated by the Committee. NOW, THEREFORE, IT IS ORDERED THAT the rules hereinafter set forth apply to the following described area: T I0 Nt R 12 E~ U.M. ~ections I, 2, 3, 4, 5, 6, 7, 8, 9, I0, II, 12, 13, 14, 23, and 24. T ..!0 N, ~../3 ~,, ~ p.M. Sections I, 2, 3, 4, 5, 6, 7, 8, 9, I0, II, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, and 24. ~. !0 ~.~ R.14..Et. U.M.~. Sections I, 2, 3, 4, 5, 6, 7, 8, 9, I0, II, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 33, 34, 35, and 36. All T I0 N, R 16 E, U.M. Sections 3, 4, 5, 6, 7, ' 8, 9, I0, ~5, 16, 17, 18, 19, 20, 21, 22, 27, 28, 29, 30, 31, 32, 33, and 34. T~ Ii N~ R II E, U.M. All T II N.., .._ R 12 E, U.M. All R_I 3 E, U.M. All T l l_.N, R !.5 E,. U.M. All T 12 N, R II E, U.Mo All T :12 N, R...12 .E, ..U..M. All T 12 N,_ R 14 E, . U.M. Sections 3, 4, 5.,. 6, 7, 8, 9, lO, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, and 36. T..I2 N, .;'; ~..../5..E,.._ U.M. Sections 13, 14, 15, 16, 17, i8, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, and 36. T.!2. N, R 16 E, U.M. Sections 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, and 36. T_~i3 N, R 10 E, U.M. Sections 13, 14, 15, 16, 21, 22, 23, 24, 25, 26, 27, 28, 33, 34, 35, and 36. T 13 N,_ R II E, U.M. Sections 17, 18, 19, 20, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, and 36. T_ 13 N, _R 12 E_, U.M. Sections 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, and 36. CONSERVATION ORDEF~ alO. 83-B Page 4 January 12, 1970 T I!. N, R .16 E~ U.M. Sections I, 2, 3, 4, 5, 6, 7, 8, 9, I0, II, 12, 13, 14, 15, 16, 17, 18, 19,. 20, 21, 22, 23, 24, 27, 28, 29, 30, 31, 32, 33, and 34. T..13 N, .. ~ I..3.E., U..M_. Sections 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, and 36. Rule I. Pool Definition. The Prudhoe Bay Sadlerochit Oil Pool is defined as the accumulation of oil that is common to and which correlates with the accumulation found in the Atlantic Richfield-Humble Prudhoe Bay State No. I well between the depths of 8,207 and 8,680 feet. Rule 2. Well Spacing_~ Not more than one well may be completed in this pool in a governmental section or governmental lot corresponding thereto, nor shall any well be completed in this pool in a governmental section or governmental lot corresponding thereto which contains less than 600 acres, nor shall any pay opened to the well bore be closer than 1,500 feet to a property line. where ownership changes or be closer than 3,000 feet to any pay in the same po~i' ooened to the well bore of another well, Rule 3. Cas i nq...an.d... Cementi...ng Requ i rements. (a) Casing and cementing programs shall provide adequate protection of all fresh waters and productive formations and from any pressure that may be encountered. (b) Wells shall be protected from damage caused by permafrost thawing by the use of refrigeration and/or insulation or by the use of slip joint casing. (c) For proper anchorage and to prevent an uncontrolled flow, a string of casing shall be set at least 500 feet below the base of the permafrost section but not below 2,700 feet unless a greater depth is approved by the Committee upon a showing that no potentially productive pay exists above the proposed casing setting depth, and sufficient cement shall be used to fi'Ii the annulus behind the pipe to the base of the permafrost section. (d) Installation of a permafrost string of slip joint casing above the casing string required by (c) without cementing through the expected zone of subsidence may be permitted. (e) Production casing shall be landed through the completion zone and cement shall cover and extend to at least 500 feet above each hydrocarbon- bearing formation which is potentially productive. In the alternative, the casing stri.ng may be set and adequately cemented at an intermediate .point and a liner landed through the completion zone. If such a liner is run, the casing and liner shall overlap by at least I00 feet and the annular space behind the liner shall be filled with cement to at least I00 feet above the casing shoe, or the top of the liner shall be squeezed with CONSERVATION ORDER NO. 83-B Page 5 January 12, 1970 sufficient cement to provide at least I00 feet of cement between the liner and casing annulus. Cement must cover all potentially productive intervals behind the liner. (f) No well shall be produced through the annulus between the tubing and the casing unless a cement sheath extends from the top of the pay to the shoe of the next shallower casing string. (g) Casing or liner~ after being cemented, shall be satisfactorily tested to not less than 50 per cent of minimum internal yield pressure or 1,500 pounds per square inch, whichever is less. Rule 4. Blowout Prevention Equipment and Practice. (a) Before drilling below the casing string required by Rule 3(c), all drilling wells shall have three remotely controlled blowout preventers, including one equipped with pipe rams, one with blind'rams and one bag type. All such equipment shall include a drilling spool with three-inch minimum side outlets (if not on the blowout preventer body), a choke manifold, and a fill-up line. All equipment shall have a minimum working pressure capable of withstanding formation pressures reasonably expected in this area at the depth being drilled with adequate safety factors. The drilling string will contain one valve above and one below the kelly during all circulating operations with the kelly. Two emergency valves will be conve~n- iently located on the drilling floor with rotary subs for all connections in use, one valve to be an "inside blowout preventer" of the spring-loaded valve type and the second to be of the manually-operated ball valve type. (b) All blowout preventer rams and choke manifolds will be tested to manu- facturers' recommended working pressure when installed and once each week thereafter. Bag type preventers will be tested to insure adequate operation and working pressure when installed and once each week thereafter. Test results shall be recorded on the daily driller's log kept at the well. (c) All blowout preventer equipment shall be adequately protected to insure reliable operation under the existing weather conditions. Ail ram type equipment will be checked for satisfactory operation before each trip. Rule 5. Automatic Shut-In Equipment. Upon completion, each well shall be equipped with a suitable safety valve installed not less than 200 feet below the surface which will automatically shut in the well if an uncontrolled flow occurs. Rule 6. Bottomhole Pressure Survey... PriOr to initia~ suStained production from each well, a maximum buildup bottomhole pressure test shall be taken. A key well bottomhole pressure survey shall be taken between 90 and 120 days after commencement of sub- stantial production and each 90 days thereafter. Bottomhole pressures obtained by a static buildup pressure survey, a 24-hour shut-in instantaneous test or a multiple flow rate test will be acceptable. The datum of the test and other details will be determined by the operators subject to approval by CONSERVATION ORDE~ .JO. 83-B Page 6 January 12, 1970 the Committee. The test results shall be reported on reservoir pressure report Form P-12 which shall be filed with the Committee by the fifteenth day of the month following the month in which each test was taken. Rule 7. Gas-Oil Ratio Tests. Between 90 and 120 days after substantial production starts and each six months thereafter a gas-oil ratio test shall be taken on each producing well. The test shall be of at least 12 hours duration and shall be made at the producing rate at which the operator ordinarily produces the well. The test results shall be reported on gas-oil ratio test Form P-9 within fifteen days after completion of the survey. The Committee shall be notified at least five days prior to each test. Rule 8. Gas Ventinq or Flaring. The venting or flaring of gas is prohibited except as may be authorized by the Committee in cases of emergency or operational necessity. IT IS FURTHER ORDERED THAT the rules hereinbefore set forth shall expire nine months from the date of this order except as may be extended by the Committee. DONE at Anchorage, Alaska, and dated January 12, 1970. Concurrence .' Homer L. Burrell, Chairman Alaska Oil and Gas Conservation Committee Alaska Oil and Gas Conservation Committee PUBLIC HEARING - PRUDHOE BAY FIELD February 9, 1971 Call to Public Hearing with respect to Conservation Order No. 83,B, Sadlerochit Oil Pool * Introductory Statement * 1. Area to be Affected by the Orders * 2. Vertical Definition of the Pools 3. Well Spacing Including Footages to Lease and Property Lines and Acreage Spacing 4. Casing and Cementing Requirements 5. Bottom-Hole Pressure Survey. Requirements 6. Gas-Oil Ratio Test Requirements 7. Methods of Preventing Uncontrolled Flows 8. Administrative Approvals, if'any 9. Plans for Disposition of Produced Gas 10. Plans for Reservoir Pressure Maintenance; and * 11. Plans for Unitization Testimony included in this volume. February 9, 1971 STATE OF ALASKA HEARING - PRUDHOE BAY SADLEROCHIT POOL INTRODUCTORY STATEMENT Mr. Chairman, Members of the Alaska Oil and Gas Conservation Committee, I am F.~Harlan Flint, attorney for BP Alaska Inc. It will be my purpose to make an opening~statement in relation to certain testimony that will be presented at this hearing. In the interest, of an orderly presentation, the avoidance of duplication and the organization of materials to be presented, the pre-unit participants have attempted to Coordinate their efforts in the preparation of the'matters to be presented to you today. In the course of the hearing you will be hearing from representatives of'several companies who will offer testimony on items listed in the call of the hearing. You Will recall that at the hearing for the establishment of temporary rules in the KUParuk River and Sadlerochit Oil Pools conducted by this committee on November 13 and 14, 1969, the parties presenting testimony were unable to Provide as much evidence as you would like to have had available to you for use in the formulation of pool rules. This derived from two sources. First, it was very early in the exploration and development of this great region and the data available to the individual companies were very limited. Second, there were compelling reasons for the operators in ~he area not to divulge information acquired by them which-at that time was protected under the State Statutes regarding confidentiality and had unique importance in the competitive conditions that eXisted. The paSsage of time, the progress that has been made in the development of the Field and the availability of more data makes it possible for us to provide you now with a substantial amount of information which we trust will assist you in the performance of your responsibility to review the existing pool rules and adopt permanent pool rules The testimony to be presented and which I will outline will, in large measure, support the retention of existing rules. The extent to which changes will be recommended will be made evident in the course of these presentations. For reasons that will be touched on later, the presentation I am outlining will be directed exclusivelY to Conservation Order 83-B, dealing~with the Sadlerochit Oil Pool. May I now outline the order of presentations. It is intended that these presentations will generally follow the eleven items upon which testimony was elicited in.the published notice of this hearing. The first witness will be D. B. Walker, a geologist employed by BP Alaska Inc., Who will present evidence regarding the area to be affected by Conservation Order 83-B. Following Mr. Walker will be two witnesses employed by Mobil Oil corporation, who will testify in support of the co-mingling within a common well bore of the Sag River Sandstone (formerly called the Oxytoma Formation), the Shublik Formation and the Sadlerochit Formation. Those two-witnesses will be H. N. Porter, a petroleum engineer, and J. F. vitcenda, a geologist. The next witness will be B. C. Anderson, a reservoir engineer, employed by Atlantic Richfield Company, who will provide the Committee with engineering data on. the Sadlerochit Oil P°ol. The next several items within the call of this hearing cover elements of the pool rules, including well spacing, casing and cementing, bottom h°le pressure survey requirements, gas/oil ratio test requirements, methods of preventing uncontrolled flows and administrative approvals. Mr. John Scott, attorney for Atlantic Richfield Company, will present the case on these items. TeStimony on the disposition of produced gas will be given by R. F, Cox, Resident Manager of Atlantic Richfield Company. Mr. Scott will cOmment on~reservOir Pressure maintenance, and finally, I will offer a statement'.On'the prOgreSS of UnitiZation. Upon the completion of the above described testimony on the Sadlerochit Pool, counsel for the Standard Oil Company of California will address himself to the call of this hearing insofar as it applies to Conservation Order'83-A, which established temporary pool rules for the Kuparuk River Oil Pool. I had previously mentioned the desire of the operators in the Prudhoe Bay Field to disclose substantially more information than could be presented to you in the 1969 hearings. I am sure it will be obvious to you that there are still some data and there continue to be some areas of the Field that require strict confidentiality. However we are confident that this hearing will provide a sound evidentiary base for the pool rules already in effect and a good basis of information which will be useful to the Committee in the performance of its responsibility to protect the public interest in this great Alaskan resource. February 9, 1971 STATE OF ALASKA HEARING - PRUDHOE BAY SADLEROCHIT POOL GEOLOGIC TESTIMONY M~. Chairman and members of the Alaska Oil and Gas Conservation Committee, at this hearing i ~m presenting geolOgic testimony on behalf of the groups involved in.pre-unitization negotiations. Following 'the previous hearing in November 1969 to establish field rules to apply to the Prudhoe Bay Field, field rules for the Prudhoe Bay Sadlerochit Oil Pool were issued on January 12, 1970. We intend at this present hearing to present testimony with regard to the areal definition of the pool affected by these rules. This is to establish whether any revision to the extent of the pool, as previously established, is necessary. At the last hearing BP presented testimony describing the geology of the Prudhoe Bay area. That testimony will not be repeated at this time, but we do present a generalized stratigraphic column to review the vertical sequence of the formations and to indicate the minor changes in terminology which have been introduced. EXhibit A is this generalized stratigraphic column. The minor changes in terminology have been made largely as a result of informal discussions of the North Slope Stratigraphic Committee of the Alaska Geological Society. Considering the section from the top.downward, an additional formation name, that of the Pleistocene to Recent Gubik Formation, has been added. Its thickness is believed to be 200 to 500 feet in the Prudhoe Bay area. The remaining portion of the beds previously ascribed to the Tertiary Sagavanirktok Formation, consisting of gravels, 'sands, silts and clays, remains as described in the testimony presented in the previous hearing. The naming of the Upper Cretaceous formations in the area now allows for facies differences. The upper part of this interval is referred to as Prince Creek Formation/SChrader Bluff Formation undifferentiated. The former name applies to coal measures - sandstone lithology and the latter name is applied if the sediments are of a more marine aspect. The . underlying Upper Cretaceous mudstones and siltstones have been correlated with the Seabee Formation and these-overlie an as yet unnamed Lower -Cretaceous-shale. Where seen beneath an unconformity,' other Lower Cretaceous rocks are still officially unnamed. In the west this interval contains the Kuparuk River Sands but over the major part of the Sadlerochit pool area these are absent due to truncation. The Kuparuk River Sands have been discussed in a paper included with the Proceedings of the North Slope Seminar published by the Pacific Section of A.A.P.G. in 1970. The Jurassic beds are still referred to as the Kingak Shale. The Triassic and Permian beds are shown on an expanded scale in Exhibit B. The sandstone lying beneath the Kingak Shale and above the Shublik Formation in the Prudhoe Bay Field, which was previously termed the Oxytoma sandstone, has been more correctly renamed as the Sag River Sandstone. The type section was defined in the previously mentioned Proceedings of The North Slope Seminar as the interval 8440' to 8482' in the Atlantic Richfield-Humble well Sag River State No. 1. This fine grained, glauconitic sandstone varies in thickness throughout the Prudhoe Bay Field from _approximately 20 feet to 60 feet. The Shublik Formation consists of varYing lithologies of limestone, shales and sandstones with distinctive phosphatic beds. It varies in thickness from approximately 40 feet to 200 feet. The Sadlerochit sandstone is comprised of sandstones and conglomerates in varying proportion together with minor interbedded shales. The sandstones consist principally of detrital quartz and chert together with pyrite, siderite and some clays. The Geological Subcommittee formed by companies involved in pre-unitization negotiations has picked the top of this sandstone at 8206 feet in Prudhoe Bay State No. 1 and the base at 8673 feet in the same well. ThrOughout the field area this base is at present picked at the lowest limit of significant sand development. The Sadlerochit sandstone has been seen to vary in thickness through the field area from approximately 450 feet to 630 feet. The Sadlerochit Sandstone and the underlying shales are referred to as the Ivishak Member of the Sadlerochit Formation. A sandstone which is present in places beneath the Sadlerochit shales is known as the Echooka Member. The previous unofficial grouping of the Sag River Sandstone, Shublik Formation and Sadlerochit Formation into the Prudhoe Bay Group is no longer applicable. The Pennsylvanian - Mississippian succession can be subdivided on an arbitrary basis into ~n upper predominantly carbonate section termed the Lisburne Group and a lower shale and sandstone section termed the Kayak Shale. In the Prudhoe Bay area the Kayak Shale and Kekiktuk Conglomerate rest unconformably on the "Argillites". This testimony is only concerned with Conservation Order No. 83-B and consequently only with the Sadlerochit Oil Pool. We now intend to present data concerning the areal extent of this pool so that it might be determined whether ~ly change is necessary in defining the area to which the field rules apply. Exhibit C is a structure contour map drawn on the top of the Sadlerochit sandstone in the Prudhoe Bay field area. This map was drawn by the Geological Subcommittee formed by the companies involved in pre-unitization negotiations. The map was most recently updated by that Subcommittee in July, 1970. The map is based on well data and the interpretation of the geophysical data available to those companies. It is, therefore, a compromise interpretation and does not necessarily represent the views of any one of the companies, but is a maP initially acceptable to all partie~. One area, indicated by shading, in the southwest has not yet been fully resolved and further work is necessary to interpret the structure in that area. On this map is shown the outline of the area to which Sadlerochit Pool field rules currently apply. Wells in the area are indicated as either having encountered oil in the Sadlerochit sandstone, not having encountered oil in the Sadlerochit sandstone, or for which data has not been released. The map shows a structure culminating in a high centered on the area around prUdhoe Bay State No..1 and truncated on the east by an easterly dipping unconformity surface. This structure has a predominant flank dipping gently to the south and southwest, with average dips of the order of one and half degrees. The structure also dips gently to the west from the high Prudhoe Bay State No. 1 area. The north and northwest flanks of the structure are poorly defined and are shown to be faulted. The northwest striking linear trend to the west is faulted along its southwestern margin. It must be appreciated that the present well data are too sparse and the seismic control inadequate for delineating details of the structure. These will be revealed as additional wells are drilled. The map.also sho~s the currently interpreted limits of the oil and gas accumulations in the Sadlerochit sandstone. In the eastern area the downdip limit of the gas cap is shown, this gas cap extends through the crestal area. The downdip and updip limits of the oil column are also shown, the updip limit being determined, from the intersection of the gas-oil contact and the base of the Sadlerochit sandstone. In the western area the downdip limit of the gas cap is shown and also the do%mdip limit of the oil column. In the western part of the field oil completely underlies the gas cap. These gas-oil contacts and oil-water contacts have been established from tests and wireline logs in individual wells. The contacts have been determined by the members of the Reservoir Engineering Subcommittee formed by the companies involved in pre-unitization negotiations. The contacts in wells have generally been established by averaging the interpreted picks of the individual companies involved. For initial studies it was accepted that in the east a level plane at 8572 feet s'~b-sea approximated the gas-oil contact and in'the west a level plane at 8775 feet sub-sea is initially acceptable. The oil-water contacts were found to vary throughout the field area and as yet the reason for this is not apparent. The agreed oil-water contacts for the wells were treated as a surface which could be contoured for estimating the distribution of the oil col~n. This contoured surface, prepared by the Reservoir Engineering Subcommittee-is presented as Exhibit D and requires no further comment except to restate that it is purely empirical in nature and was acceptable to the companies involved. This map was used to construct the oil-water contact traces on the structure contour map (Exhibit C). To illustrate further the structure and fluid contacts of the Sadlerochit sandstone in the area, two cross sections have been prepared, approximately west to east and south to north across the field area. These sections have been drawn on the same horizontal scale as the previously presented structure map although they are expanded at the well points to include the well logs. To indicate the structure and log characteristics, a vertical scale of 1" = 100' has been used which gives the sections a vertical exaggeration of forty to one. Exhibit E'is the west to east cross section through Atlantic Richfield- Humble's North-West Eileen #1, Mobil/Phillips' West Kuparuk, Mobil/ Phillips/Socal's 7-11-12 (original) and Kuparuk State No. 1, BP's 09-11-13, Atlantic Richfield-Humble's Prudhoe Bay State #1 and BP's 31-11-16. The resistivity logs for these wells are shown for the Permo-Triassic interval and the immediately overlying beds. The Sag River Sandstone, Shublik Formation and Sadlerochit sandstone are correlated through the area. in the east the position of the unconformity is shown truncating the Sadlerochit sandstone. The cross section has been left blank near the area which was indicated to be as yet unresolved structurally. The electric logs indicate the distribution of permeable beds, and the fluid contacts have been placed on the diagram to conform with the map (Exhibit D) for the oil-water contact and with the defined gas-oil contacts. The south-north cross section (Exhibit F) is constructed following the same principles used to construct the west to east section. This south to north cross section passes through Atlantic Richfield-Humble's Put River State (7-10-14), BP's 32-11-14, BP's 27-11-14 and Atlantic Richfield-Humble's Prudhoe Bay State No. 1. This section indicates the main south flank of the eastern culmination extending up to the Prudhoe Bay State No. 1 area, and also, a fault between the wells Put River State No. 1 and 32-11-14 is indicated downthrowing to the south. This fault interpretation was necessary to satisfy the well data and has some confirmation in seismic data. To return to Exhibit C, the structure contour map on the top of .the Sadlerochit sandstone, the area to which the field rules in Conservation Order No. 83-B apply for the Sadlerochit Oil Pool is outlined on this map. In light of the results of the co-operative studies of the extent of the pool which we have presented here, and realizing that our knowledge of the area is far from complete, we do not at this time request any change in the area to which these field rules apply. This concludes the testimony concerning the areal extent of the Sadlerochit Oil Pool and I wish to th~nk you gentlemen for your attention. February 9, 1971. STATE OF ALAS}ZA HEARING - PRUDHOE BAY SADLEROCHIT POOL PLANS FOR UNITIZATION At the hearing on November 13, 1969 a letter of intent, previously submitted to eleven companies, was presented to 'the State. This letter outlined a proposed ~nitization of the PeN-ac-Triassic hydrocarbon acc~nulations as defined by the Pru~_E~:oe Bay State '.',~o. ].. well. The letter was agreed to by all parties shortly after the hearing. A copy of the letter of intent is attached to this submission for your records and basically outlines an agreed to basis of mnitization. In the fall of 1969 the Steering Committee convened and the Subco~nittee structure was organized. This organization is shown on the attached plat BP No. 1 and the area ~o be unitized initially is sho%>~ on Exhibit No. 2. Since that date the subco_~ittees and various task forces attached to the subco_n~mittees have been meeting on an almost continuous basis and a great deal' of progress has been made. In order to illustrate the amount of effort that is being devoted to unitization, tb~e attached Table shows the approximate man hours that have been applied to the effort of negotiating the te~0.s smd conditions to be implemented. It must be realized that in light of the sparseness of data and 'the enormous size of this pool, it is imperative that every consideration be given to the possible factors and future events that may effect unitization. This, u~fortunate'ly, requires time. However, definite progress has been made and every effort is continuing to lead to as early an unitization as possible in order to optimize the development of the field and to protect the envir?nment of the North Slope. It was felt that a ?.~..: oft on the specific progress by conunittees and subcommittees would not assist the Committee at this time, however, we would like to point out certain areas of progress. The Legal Subcormmittee has prepared a draft Unit Agreement whJ_ch has been discussed with the Oil & Gas Conservation Committee° They are currently working on an Operating Agreement. The Geological S~Dcom~Littee has prepared geological maps and has reached agreement on the interpretations for the majority of the field. It is hoped that complete resolution will be possible in the near future. We would especially like to indicate to the Committee that, although unitization has not been completed, benefits are already being derived from pre-unitization efforts. The Environmental Subcommittee is actively engaged in studies to protect the ecology and to conserve the resources of the area. The Operations Subcommittee is coordinating operations on the Slope to minimize surface usage smd disturbances. In addition, %he guiding principle behind %he pre-unitization negotiations is to develop a plan of unitization that will optimize conservation and protect correlative rights in accordance with the State Statutes. P,o :-:t o,, .:tic'.'_: I '(; D~.llt::;. 'Fo: ::c::. 'i-olcp!acni,'.' 2i4 7.~7 E. L:. ti:ep, uc, n, Jr. Oc:[oLo]: 29, ]969 S~;and:.'trd Oil Comp.m~, of C']ifornia iv. O. ]3ox 3d95 San ]~'ranci. sco, California 9d]20 PhillSps Petroleum Comt)a'.U' 1300 Security Lng. ]3uS]ding Denv(:r, eel. oracle S0202 At-toni. ion 3,'Ir. C. W. Corbett. Mobil Oil Corporation 612 YlowerD.z-'~uet.'- o'- --~ ~[-~ Los An~l .... , California 90054 Hunt .Po ~ olccm, Corpor etlon 2900 _~irsc ~x.t.].onal Ean].:]3tt~lctn~g'" ' Dallas ' -- ' , Fo.=as 75202 Am er ada- }Jo s s P.. O. Box 20dO 'Italia, ()].:].ahoma 74102 Getty Oil Compm~y- P. O. Box ]/104 ttouston, Texas 77001 Louisiana Land & F_,.x])]ox-at:/on Co. P. O. ]:,ox 60350 New Orleans, Louisiana 70lC0 Marathon O~l Company 0o9 $om.h 2i ain Findlay, Ohio d 5S-J0 Gent:l(,men- Proposed Cooperative Development Prudhoc ]_',, y ]?ield Tou e:tch ],:'rye been fu~'ni:;],,z,d with l.,,y and t)etwc;c;n ..... t,-,e up,,~,;::;i",',,~ud,,, ]()~'.'..[i'l':',., fr)l".,'.,';ii'd t,') ',.!:lJJ i"'~( J,-);l Of I]~:.' Page Octobcr oi] aud gas interval s.'.~.:,~d body State Nc). I_\Vo]i bel.ween the depths of 8,066 feet su. bse:~ and thc carboi~ate' formation at 8,7,17 fe.c,t: sul:,sqca (t~erc/n''c',,,,er called ' [lk~,'~o--. Triassic"). Tort eaclt hereby are given the unitization project which is the subjcc¢ underscan aing that. lm each separate Permo-Triass/c reservoir under]y'~n,,',' thc unit area, when defined, will const:itute a sel)arato oil rim and a separat'c gas cap participating area or area(s). The 1)robable first /r/rial part/-- cipnting arcat,~) lie East of thc li~a labc]cd on Exbibil: A-]. attached hereto as '?articipa.ting Area"; such area(s) may 1>3 adjusted at: th(: times prox~ded in paragTaph 2 of the letter of Augusi: G, 1969; g. ~he plat aH',~,cned ]~,.j:et.o as ]zx,~m:: A-lwill be. and hereby is tuted for .... ~ , u<. plat: attached as E>zhjbit A to tho afore:said ].el:lot- lhat such letter shall be and is he;:eby amended to include each of yOu as a party hereto x:Jd,, tho san~e force m~d effec, t as if m~cn as so ameLaed, had been executed and/or accepted by you and by of us; e the leH:er of August 6, 1969, as here.~n amc,haled and rat/fie, d, is construed soleJy as a c'.omm/tmen~ on l. he part of eac:h pari:y to said ]cfi:er to negotiate in good faith v,,i[.h the oilier parties to .ac:h/eve unit- o.,,-ford, l.l:ercfn. Such let-- jzation in accordanm with thc prfl~cfples let shall not commit any party to [:he execution of any document which proves im~,CCcl)[aol~, to R Neither' shall l:be execution of l.]~Js (or l:he let.ret of August 6, 1969) bc cons[tried as a waiver by any party of any legal or equitable rigger, whie]~ ~t otlm]'wisc would have; provided that ,no~n_t,o~l 4-.-- herein shall be construed to n,_.~,tte-.[,"- ' or r( ]}P, id. lant.~c or Htunble of any coi'ninJtmc, nf.s undertaken in or pur- suant to the lel.tcr of Attg'ttst 6, 19{;0; any geological, seismic, well or related info~'mation lands within the unit: area, as s]~ov.-n on ]:;xl~il.,/t A-], wl~Jd~ u'e may ~-nakc avail:rifle._ t-o you l)UrSUaut lo tl~fs letter a~cl du'~'ing, t]c,,~)i~_, irttion,; toward formation of the unit shall. 10c, hr:Id co~tfide~di:ti by you ftlld ~ot be cli~;c]osed by you to anyone v,']~o has; not. ac('~..!~ted'/}~i:4 letter prior to consmnn~:ttion of l}~o Unit A?;rce~,:,~t, v.'hiel}evcr is later, w/t!-:ou[ our v..'~'itte~ 29, ]9(;9 -}~ ,-~4 'vio- Aprf! 1~, i970. ~t_ fs n~t'.~ -;'.-,, ' ' .. will 1.,o made oomn~ fi.[ ecs are ll~pO?t~tBt 3~3ttors wi]] If you aga-oe to jofl~ with us, and wfi:h auc]~ of tlm ot]~er addrcsseos of . . this letter as agx'ee to join., ~n the und...rmk],~," dcscribc~d i~ said lci.i:cr as heroin amendod, please so indicate by e:~ecttl:~.;~[': and by rehtr~'~n~ copy of this letter to each of the undersf[;'~ed. \,Ve would apprcciate your reply to l:hJs le~tc~.' by lqovomber ].0, but in any evcni: not la. tot than ~amtary 1, 1970. Your f_: very truly, ATLANTIC ~xlCI-]_FI z.~D COMPANY By E. ld. ~enson, Jr., Vice President 1°. O. Box 2819 Dallas, Texas 75221 BP O]iL COIlPOllATION By · 620 FJf[h Avenue New York, New '~fork ]0020 lP;',~¥; 4. Oc[d.)m' 29, ]969 A C C E P'I' ND A ND AG R E ED TO Thfs {la},' of , 1969 SIANDAL O~L COMPANY OF C~'.LI] PHILLIPS P],7, TROLE U2'~ C.30)~%PA NrY By ]~OBIL OIL CORPORATION ]3y ttUN'P PET~t~O]..,~,U~'I CORPORATION I3}, AIMERADA-- I-tE SS By GETTY OIL CONI])ANY LOUiS]AHA I¥IA)iA. THON OIL CO3IPANY ]']?,ll",: cl Al,[ :t c,] ~)'n ¢'1~1' :; I PARTICI PATI AREA ,t Aug*dst 6, 1969 BP Oil Coz])oration 620 ~: ~.~tu AvOIItiO Nexv York, New York 10020 Htunble Oil &: Refining Company lP. O. Box 2180 Houston, Texas 77001 Re: Proposed Cooperative Development I>rudhoe Bay Field Gentlemen: In order to promote conservation, t'o increase ultimate recovery, to eliminate unnecessary drilling, to avoid was[c, and to insure each partScipant a reasonable opportunity to recover its fair share of the oil and gas in place, it appears desirable to us that the oil and interval sand body which was 'm~countered in Prudnoe Bay State No. 1 Well bet-ween deptl~s of S, 0GO feet subsea and thc top of the. ca~:bon,.~e formation at S, 747 feet: ¢ ' otlDSOa 2S deternunec~ by reference to dual induction lo~ of said well dated Riarch 9, 1968, and furnished the pa~ies hereto underlying the tm Jr area out-- lined on the plat attached hereto as Exhil0it A be developed, operated and produced as if the area had been included in a single lease. coromg]5., we propose dmt amoro:>riate legal-and unitization committees be appointed to commence .~.,_ne_~,ateis- after the ne:dc competitive lease sale (eqoected about September 11, ].909) to agree on definitive forms of a Unit Agreement andaUnit - '~ i'-~' '' ' Ope~,~t ,,s Agreement xvn~cn would, among other things' 1. tSstablish separate participating areas 'for the oil rim and the gas cap each with sepa- rate ownerships within the unit area based on At!a,.q,,c ~,~ch,~ul,~Compa nY -2- oil ori,,'naliy in place aud gn.t-; ori,,-inally in place with each tract in each partici.- ~i,.~, area l.>cin!g ai!ocatc, d ils :~ppropriatc p(:rccnt, agc of production uno. lot tho Unit Agreement anct xx ich each tract, worki~'~i;' interest owner bearing thc royalties, ovcrricii~¢p; royalties and production payments on produc- tion allocated to the particular tract and ].ease burdens applicable to such tract, A~y lease covering lands within thc Exhibit A area proven to be productive in thc same sand interval and subsequently acquired by m~y party hereto may be added lo tho unit on the same 10asis. Each participant shall take its share of the oil and gas in Mud and separat, ely shall dispose of its sh_are of the produc[ion. !n any event fi~c benefit of discovery royalty on production allocated to tl~e lease on which Prudhoo Bay State No. 1 well'was drilled shall bo shared equally by Huml01e and Atlantic' Richfield. 2. Make initial separate determination of oil and gas orig-inally in place underlying separately owx~cd tracts included within thc ~it area outlined on Exhibit A, by April 1, . based on aa.a available as of Septomi0cr 30 19~9 and anothcy separale de~crmfl~afion of oil and gas o~iginally in Place underlying selSara~elv owned tracts zncmdea wi~llill the unit area outlined on E~ibR A, by Jammry I, 197~, ufilizin~ data~ available as of July I, i97~, A final and Separate determination of oil and gas in place underlyin~ the separately owned trac~s included within the unR area will be made by ~anua ~ I, 3. Each party shall consult with other parties hereto as to location and projected depths to be drilled on all wells projected for completion in the subject sand in order to assure an orderly develop- mcnt of the field in accordance with sound cng-i- neering principles. -Notwithstanding anything herein AtlanlicRichlieldCom?any to the coutrary, each party :ti ii::; ,~;olc risk, cost :t~:d expense shall bo f~'cc lo dove, lop i. ts activity it alone soc::~ fit. It is; that the unit agrce~.cD.~, a. nfl th~ unit. agreement.make al)proi:)r J:t t(~ adjustment as to such 12uior however, the unit shall t~ot be r~c..ccss:trily oblisatcd to pay for we~ls not ~,.,:S. eed upon by the aDove conou~.tation. 4. Permit the owners of the oil rim. participating area to store, at their sole cost, risk and expense, solution gas in the g'as cnp or in another appropriate sand tu~dcr]ying the . unit area. Sin. ce a given well sin~uit~tneously may produce oil, solution ~as ando~"°~'~,~ cap o.,,~: a formula will ise included in theo~', ~, 'ac~.no"' *~ a,.,rce~,- men~ setting out a ~ne[.,~oc~ of scl:stately ll]o/lsttritl~ and accounting for such products where that condition occur2.' . 5. Provide5 ~'or possible expa:~sion of the unit area and revision of the participatin[~ oil rim and g'as cap areas, o:a thc b':~sfs of oil and gas respectively originally tn pl:~ce, with provisions for handling investment adjustments, prior production.and other relevant matters upon expansion and revision. 6. Provide for n~ore than one Operator, with BP being one of the operators. 7. Provide for formulas that will allocate the relative production from the gas cap and the oil rim. 8. The participants in the oil rim partfci--- paring area agree to the objective of dcvelol>::'.ent of the field as quickly as is economically prudent so as to permit each such participant a level of Atla ntic P, ichlicldCompanY offtakc not later ti-:;~.n January, 1976 of at in place under thc !ca. sc:~ I'n'cs,_~:i~t].y owned or be c)btah}ed by each of 1he par t:icilxmt~ xvid~,n ...... All the foregoi.;;~ is subject to vr~lid rules and regxflatim~.s of the State l::e~;u!:'~.tory Agency jurisdiction and to applicable laws, rules and regxfiations of thc c .... of ,~'~,.I~,~ a,~d the ~ -~ n . , Government of the Umw. ca Stares. the above is in accord.'.:tnce xx xta your under,~;tand~ lng, please execute and return to us one copy of tins letter, Yours very truly, .:.5'~ '/! .-y--<, -)--- .. ,. o T.F. Bradshaw . .. ACCEPTED AND AGREED TO ~.~ -P~., 4' / 1969 this ..... ' day of BP OiL. OOItPORATION . TFB/sa EX!i II-~ IT "A" PRE-UNIT ORGANIZATION B.P. NO. PROPOSED PRUDHOE BAY UNIT MANAGEMENT COMMITTEE STEERING COMMITTEE GAS CONSERVATION RESERVOIR ENVIRONMENTAL , GEOLOGICAL SUBCOMMITTEES ENGINEERING OPERATIONS i I FIELD DEVELOPMENT 8~ PLANNING TAX ACCOUNTING Il LAND AND LEGAL . TABLE approximate Man Hours on Meetings of Su~commi.ttees to Date Ps_mc Nan/tlours S,0Jocoms~ittee No. of FoN~ai Meetings '' ~ Accounting 1! 1,900 Environmental 12 1,100 Field/Dev. Planning 7 2,300 Gas Conservation 5 6,500 Geological 10 7,000 Operations 12 1,20u Reservoir Eng. 15 42,500 Land and Legal 12 7,200 Tax 8 600 In addition to the above major subcommittee meetings and preparatory work, various small task forces have been conducting work on .an almost continuous basis. HUMBLE OIL & REFINING COMPANY LOS ANGELES, CALIFORNIA 90067 PRODUCTION DEPARTMENT WESTERN DIVISION HARRY PISTOLE MANAGER August 14, 1970 1800 AVENUE OF THE STARS Ref: Conservation Order No. 83-A and 83-B ' Prudhoe Bay Field Rules Mr. Homer L. Burrell, Chairman Alaska Oil and Gas Conservation Committee Department of Natural Resources Division of Oil and Gas State of Alaska 3001 Porcupine Drive Anchorage, Alaska Gentlemen: --j-'~. ~_,',,,~c~ ,.~ . i._~ ..u ',, ,'s I_.4 E>'.G I 5 ~-h"..:; ...... ) "i cz ~:,';:...l'Z ..... I''t c~'":;~" 4 1..D 7.?',FT .... / S'?:C ...... "d'" '"" C.,.,'; df ,. .................... i:iLF.: Humble Oil & Refining Company respectfully requests that the Prudhoe Bay Field Rules be extended at least 90 days beyond the October 12~ 1970 expiration date and that any Field Rules Hearing which may be required be postponed correspondingly. The Prudhoe Bay working interest owners are aggressively pursuing unitization of the field. Preparation for a Field Rules Hearing in the near term would require that manpower be diverted from the unitization effort. In our judgment, extension of the Field Rules will in no way be detrimental from a conservation standpoint, but would, in fact, aid in our conservation efforts by hastening the day that unitization is consumated. W~ therefore, respectfully request that the Field Rules be extended at least 90 days. Yours very truly, ~ 'a~i s ioP~Sptr°ol~ction Manager WCG: gc 'BP ALASKA INC. P.O. BOX 4-CCC 121 WEST FIREWEED LANE. SUITE 205 ANCHORAGE. ALASKa 99503 TELePhONE (907) 277-1422 ]~INERALS BRANCH DaYe August 12, 1970 Noted by Branch Chie£ ..................... A-04560 Dowling .............. Secretary .......... Assigned Route in Branch ................ State of Alaska ~,, ,,,.~..~_~ ~' Department of Natural Resources Division of Oil & Gas ~aska Oil & Gas Conservation Co.tree ~chorage, ~aska 99501 . Re: Conservation Orders 83-A Rnd._83-B ~rudhom Bray ~i~d i Prudhoe Bay Kupar~ River Oil ~ool Pru~oe Ba~ Sadlerochit Oil Pool Dear Sirs: lC. G[OL I1 E~G .... [ 2 ENO I 3 ENG [ 4 ENG .J 5 ENG · ..... I'a G~OL [ ...... I~A~'r .... I._~ I sec I CONFER: The rules for the Prudhoe Bay Field established by Conservation Orders 8j-'A.'- ' and 83-B will by their terms expire on October 12, 1970, except as they may be extended by the Alaska Oil and Gas Conservation Committee. As you are aware, this company and other lease holders in the Prudhoe Bay Field are actively engaged in negotiations to establish a Unit Agreement and a Operating Agreement. your reopen hearings on Unit Should Committee the y Prudhoe Bay Rules on October 12, much of the effort now directed towards the , , Unit negotiations would be diverted to prepare our presentation at such hear- ~v ~z-/%~F~~' ~ings which we feel might materially delay our efforts toward unitization. ~Therefore, we hereby request the Commission to extend the rules established <by Conservation Orders 83-A and 83-B for apjproximately one month until mid- Inasmuch as ConServation Order 83-C, establishing rules for the Prudhoe Bay Lisburne Oil Pool, contains no specified time limit, it is our understanding that the rules established by Conservation Order 83-C will continue in force and effect until modified or terminated by the Committee, and need no action by the Committee for their extension beyond October 12. R E r F iV 9 )DIVISION OF OiL AND GAS ANCI'-IORAG~ ch Very truly yours BP ALASKA INC. F. Harlan Flint Manager, Land & Legal AtlanticRichfiel~lCompany Lecj@~ ~iVi~i'r ' Pos~ Office-'{ :. _,0 Anchorage, A~aska 99501 Telephone 907 277 5637 John R. Scott Attorney August 12, 1970 Alaska Oil & Gas Conservation Committee 3001 Porcupine Drive Anchorage, Alaska 99501 Attention' Mr. Thomas R. Marshall, Jr., Executive Secretary Subject: Prudhoe Bay Field Rules Conservation Orders No. 83-A, 83-B & 83-C Atlantic Richfield Company respectfully requests that you extend the Prudhoe Bay Field Rules for an additional three months. It is further requested that no hearing be held prior to November 30, 1970, for the purpose of hearing testimony to determine whether, or to what extent, such rules will be made permanent, revised, replaced or supplemented. Each of the Conservation Orders referred to above contains the following finding' "Unitization of the pools within the Prudhoe Bay Field would conserve natural resources, prevent waste, and secure other benefits including that of eliminating unnecessary opera- tions, thereby minimizing adverse effects upon the ecology." Diligent efforts to accomplish the desired unitization are in progress. Many of the people who are directly involved in those efforts would be required to assist in the preparation for and to participate in any further hearings pertaining to Prudhoe Bay Field Rules. Such people cannot undertake both of these tasks simul- taneously. Therefore, the rapid progress now being made toward unitization would be impeded by any such ~earings. It is anticipated, however, that this ALt G 1 197 0 O[V~$1ON OF OiL AND GAS ANCHORAG~ Alaska Oil & Gas Conservation Committee August 12, 1970 Page II situation will have been obviated by mid-November of this year. It is, therefore, respectfully submitted that the requested extension of the subject Field Rules would be in the best interests of conservation. v~truly yours, ~hn R. Scott ~ttorney JRS: j ob CC: Mr. Homer L. Burrell, Chairman Alaska Oil & Gas Conservation Committee Mr. O. K. Gilbreth, Jr., Member Alaska Oil & Gas Conservation Committee EXHIBIT LIST Conservation Order No. 83 No. Assigned by Committee 7 !0 Date Received November 19 November 24 November 26 November 28 November 28 November 28 November 28 December I December I December December Submittin~g Party Concrete Research and Technology Gerald Ganopole Humble Oil Company Pan American Petroleum Corporation Standard Oil Company of California Hamilton Brothers Oil Company Loui~i~nal.~,~? .and Ex~loration Company Marathon Oil Company Highland Resources, Inc. Mobil Oil Corporation Pennzoil United, Inc. SOUTH NORTH BROOKS RANGE SOUTHERN NORTHERN FOOTH ILLS FOOTHILLS UMIAT COASTAL PLAIN ARCTIC OCEAN UPPER CRETACEOUS- TERTIARY LOWER CRETACEOUS- MISSISSIPPIAN BARROW ARCH SCHEMATIC CROSS - SECTION ACROSS THE NORTH SLOPE TI3N TI2N TIIN TION T9N ALASKA-NORTH SLOPE PRUDHOE BAY AREA ~4~, ~ ~4.~ .,~:,; -~ ...... ~:. ..... ~ .......... ~ . .... ~. ~ ~.~: ..... ~ - ~. :_ __~?_ ...... A H A 282,tl w ,~up~u ST ..... ~ '~'~ ..... ~, ~.~ .... 28257 AH ARCO Mb So 20ti4R ?¢/42 ARCO A H 256 5 g 2 D 2.1 J §P II ? ~ ;!LiH - 202H; BP RP A H A H 2~JR4 A___,~ ...... L_H ...... ?R3Oh 2 B:~llb A H Pt?U D BA `3,~b 75 HOE ...... .B.P. .... ARCO ARCO PI. A¸ H ARCO UPi HE, MI ST0 ...... --___J_____ A¸ R A H J H AR~O 4 m H ARCO ,,~ So "-Tl'7'E'~ ......... ARCO ARCO Champ ARCO 474h4 U o P I . ARCO ARCO Champ l On Sholmeye~ ?RYHS Co Sun 01 ARCO ARCO 47477 28290 ;0 RIH1,CJt¥ S ARCO ARCO ARC0 ARCO BP BP BP BP 4/472 28313 pUT~R STi A~; H A H Am. H AmTI H C h 4H1U1 L oH Am R So[: R~nll ARCO k(o. Pi A H 2 T-II-14 28812 28314 ~o Pi A H A H 8308 2H,!20 A¸ H 11 BP 28343 3P-Il-16 A H A H A H A H R R 28377 28345 28331 283321 28346 ~"8 ]34 2 §'3`3 :{ /H;14R BP A H PR, ID- BP 283 3 5 Soc. BP f,~o Pi k~o P UPA 31-10-,6 BR UPA U P A ................... ~__ BP 78~4 47412 41502 4t50`3 ARCO U.P A 28,341 47474 47514 ........ ~ U PA 78348 41483 BP UPA U P.A U PA 0 KADLER S1 41 Ii `33 U P,A U.P A Sholmeyel ARCO 47505 47504 ARC 0 4/RD9 ~0 SO SCALE 4 6 B O MILES m,m ..... EP..JLL~-._ ......... 47532 P e n n UPA Pi, , UPA fex ShPII [1o pi IOh,nnp) Ol) TI3N NUMBER TI2N BP BP ALASKA ARCO AILAIITIC RICHFIELD A H ARCO HUNBL[ A~R A~ERADA HESS et CoS!:n Ctty S CORTINEIITAL 0IL SUN 0IL CITIES SERVICE Ha~ H~BILTON el mo P~ ~OBIL PHILLIPS mo ~, SO ~OR~L PH)LLIPS SOCAL So SlANO~RD O~L OF OALIFDRNIA lex TEXAO0 U P A UIJ~OH PAU Gert Am OEN~ AL ~o So ~OB)L SOCAL PENN - ~ENNZO)~' 8P ~¢0 -BP A~$~A P.R.~ B.P. PUT RIVER WELL S.D.~B.P. SAG DELTA WELL TIIN WELL WITH OIL WELL WITH SANDS ABSENT TION AREA COVE R IN G PRUD HOE BAY _ KUPARUK RIVER POOL CU ML.J LAx-TI VE TH ICt4, N£S£ IOOO- 3000 ~.000 5000 - ~000 - '7000 - OIL 8000 9000 oas ~0000 O~L · Gz~S8 iI OiL I OOO I kO00 FORMATION (I N FORMAL ) APP ROXI h,/i/~l- E'_ AGE 13000 14000 0 0 0 © b: L.'-- 0 0 0 0 C; 0 C · '0 '' 0' c c: o o O SA O AVA N1R KTO K ..3 000 - _.%000 5C H RADER BO00 .FT BLUFF / EABEE / TORO K .... ¢. 1800 FT KUPARUK RIVER _Ff.'O'l~ M ~Yi O N 0- 800 FT KI NGAK FORMATION 0 - 1800 FT .... ~ .... .,..- OX Y TO_M__A_~ c. 30 F T '"----$HUBLII~ c. 80 FT -~: SAND 600 FT 5ADLEROCHtT --- SHALE ,:~OO FT --- LIMESTONE QUATERI'-IA R Y --,-- SAND & SHALE TERTIANY UPPER r' 17ETACEOUc LOWER C~ETACEOUS LOWER CRETACEOUS i JURA.'SSIC PIRUDHOE BAY GROUP ~TR-i-AS~3 ~ ..... PENNSY ~LISBuRNE MtSSt%% LVANIAN PPIAN PRE-UPPER , ~l DEVONIAN ARGi!_ L .ITE S GENERALI. Z ED 5--FRA-Ft cSRAPHtC2 COLUMN OF PRODHOE BAY AREA .N.B. FIGURES AT LE~ ARE NOT DEPTHS "1"~ ].,.,,,,~ OIL Cn;.'!Pt\,,IY OF CALIFORf'tIA LmJECTIfir,ts AT Tills Tii'.'IE bY S'fAi~,IX,,ip-;" .. . : RECOMNENDED PRUDHOE 3AY FIELD RULES .]_-C, 2, Ar,ID 11 AS PROPOSED, _~ULE 1-C - DEFIr~ITIO!,! OF POOLS THE PRUDHOE SAY I(UPARUK RIVER Pool REFERS TO AN INTERVAL. WITHIN THE CRETACEOUS OVERLYING THE PRUDHOE BAY SAND POOL, IT HAS BEEN DEFINED AS THE ACCUMULATIOH OF OIL AND/OR GAS COMMOH TO Al'iD WHICH CORRELATES WITH THE ACCUMULATION FOUP.,~i') II',l I'!OBIL- PHILLIPS i.iOR'FH i<UPARUK STATE #1 WELL BETWEEN THE DEPTHS OF 6765 FEET AiiD 7060 FEET, THIS INTERVAL. IS TOO LIMITED FOR 1'HE CRETACEOUS AND SHOUL. D BE EXPANDED TO INCLUDE 6765 FEET TO 7765 FEET IN ?'iOBIL- PHILLIPS j'~O RTr'I '" " " RUPARUI( STATE iF.]. WELL, RUL.._E_ 2 - SPAC! JIG DENS I T_Y_ I(UPARUK RIVER POOL AS WE HAVE DEFINED IT ABOVE SHOULD NOT BE INCLUDED IN THE'PROPOSED GL$0 ACRE SPACING PER POOL, THE KUPARUK RIVER POOL SHOULD HAVE A ¥'.tELL DENSITY LI.~'iITED TO NORMAL STATE OF ALASKA SPACING OF NOT LESS THAN !~0 ACRES PER WELL AT THIS TI I"~E, RULE it-.EXTE~ISIO~.I _O_F SPECIAL FIE.L_j~) RULES TO OTHER POOLS ~'~ULES GOVERNIItG THE PRUDHOE BAY SArtD POOL, P,qUDHOE [~iAY LISBUR~.iE POOL AND i(UPARUK RIVER POOL SHOUL~ r,iOT APPLY TO OTHER POOLS YET TO BE D~ISCOVERED ~4ITHOUT THE BENEFIT OF A H EAR I N G, Jefore d~ilLing a ~,cZ~~Ou- 'w,~i~s in the Prud?-'~,:: gn opera.or shat~ submi{ an~ rece:~.v< avOr~va~ of' a ~:~_ ~1% Of' all sands and (2) from an"_ ~r,::,:~ e ~:,~.'- .,.~y ~: encou. . . '~ .. .... ~.., ' ~' o~a:",ato <'::tends' _c, ~..,se for su . production or-injection of ~-:~rm'=''- ~ ~lds ,~aal~ ....... pr~uec'ued to sauisfact: .=o,, of the Committea ag6JJnsu pe,rmafrosu condlui'ons,. casing and cem~nti.ng Practices ~nmo_~. 'ao S'''~ ' .... ~ .., shall be aetermined as provided'.~n xu~= lC ':e:ec:f fo~' saCh and practices no~ previously approved. - . , , (c) Production casing sha,ii..be .landed th'~'O'uqh'the comple zone and cement shall',-.cover and ~'~~' ~ ,~'t..' least '500 fee? ~ach hydrocarbOn-bearing for:nation %~?:ich :~s po:::.,::,nti~lly proc, Zf ~:o hy~cocarbQn~bearing formation.exis'~,~ t%~c .::,~ pcte'ntza/L. 2rcd~cti"~ in the inte,rvai.:b~%wee~: i:'he,"s'ho~ of c'ha ::-:~e:~:':' ~i"Z hot "be requ'i'red' "~ :ti~ in the, ~hoe "o~f, ~uch shall,.::t,,:~,~J .... Y:' , .... ., :..,., :,.::,,, ~.,/. . . A~.ternately, to ~ ~c) above~ a casing s.zr~..~.:.: ::::.a~,' se:t and adeqUately cement'ed .,:z.an:interme.d[a -poznt and. a liner lanaed t'h::o:~gh ~he .complet:o: zone, If such a liner is'ru:~'::~ the casing:' and shall overlap by at ieas,t, i0..0 foci, aid. the: annui,<.r ,,space behind the l'iner sba! ..... ~=!e,&;,,w~ 'h to at least i00 feet 'above ~::~: cas. ing~.~.ho'e,' o:~ '?'top o'f zhe.' liner shall be~','squec:~..ed.'wi~,:~' 'Suffi'c:en': ~ cemant-to.pro~ide at lc. asr,100 fe~t of ce,,en~ ween the, :l.iner'and~casing annulUs.:[. Cemen~ taus,%, ~ cover all .Po:te'ntial!y '~rodUczi~e,<i'nte'r. vals ~,~.~~,~-,a' ' · . · . , .. . ,, ' ... ,', ,.:;: [ : ~ ~ '.tho liner. . · . -?. , ,'..::" , " ~ '~ . · ~ inz~rval .may. 'be..".Compieted , as' 'an"(,.:'~.gPen,'"..hb:le cor~- -' -~ ~ .: D~'tion""6r,.'a': "i:ine'r piace'd and'.'.l'e'f't' 'un'C~men%::i ~ / , i.~ ca'sin~'l':X:s',~s.e~, ana ~c:eaua,~e,ly.., cemenzea ,.no~. , - . ~,,,'.'. '~,.., ,,.., . ' '-- . . . ..,',.,,,, '. , '. .,' , . ~ .... ' " ' eet aaov~.'the.'eom let~an'zone:. "'' ~ mo, e , than ,. 200,, f ..... , P ..... ~ ,__ '.. .,. ...... . i:.: ,' ,, .:.. ~ . :, .-,::,..,,,:., /. ,,? . ,,., . ... ~ .... __ ..~:. ;'. ?,. ;:;, · .,,, ,:,, ,. . .,.,?.......,, ,.'~ .,. . , . · d) C~sing' (Or":'li.h.g'~),~..f'~er.'being?.:.c'emenz-', ~ shall be factoril~' teS:~ed.'.tO :.n,bt ,less th~n.,,..50,~: of.:.,m~,,,..~,~::: ~ _ressure, or,.i:,SO0 :pounds per ~q'ua'?,,,/~i'n~h, wh:che.v~r , ,' . . , . ,,:, .' ,, ~ .'Q.~;" , [,'., ';.,:... . ..,, . ., ,: ....... .,., , ,, .,, ,..: .., :,.,..,,.,. :.,,:'.,, ~.,.. , ',':( ..... [""'"":'" "'/:' '"'" ~ "'.' ":""' ' ' ., , 'C' ',~ ".'"',: '." ' ~ .... t, ', .', ', .... ,<..." ,, ,.., :. ,.'., , ........... .:.....,.... '"' ' . '-'. ":7 ~,.a ;~.~: ' ,,:,.'-'.:., '..:, . . . . . . ':.,'. ... .. :.,~,..., ..,.. . ,...:.,, :, ,.-..... .. .. :. :,'..:...:,....,. :.. '. '' I. .."' ' ' ' ' , , ,. . ' . ,. ~', ..', ...' ,.~. .... ~' ,?..,,: ,,~:/.....: ' ,,~,. ",. ::'. ,.,.... . ".. ',?. :.,¥.~ . ; , . ....., :..:.-',. ~ :?>~ ,,. ,. ,,., .,. . ."~ :.,,:':.~...:'.," . ',. ~] ....... :.~ .......... : ......... :.. ................................................ : ........................ : ....................... ~ ................ - .................................................................. to hold a :',~ ...... ". ::::. :'.~ .... ..::ar te ,-. :-.'.: .' ~'- '.: proper 0:.o1 ~. :,.,;s Lo-' v:'-- :'n.,lnoe ?-. v . _d ~Y u~ailfor.~..~ ]o::;.~::... own C,'~ a: ..... Lee: '~ las'J:. :. c ,zering [,,.t.~ (':;3 :?c:: I~ ~e:'~"'"~~.~,, .~,~: ~:h.:. ?vudhoe Bay ar.:.:c. such new rule or change, r:',o,, ........... ;,:.:. .?: rep,: ALASKA-NORTH SLOPE PRUDHOE BAY AREA ; :-' 1~ '%> ~ ,i , i, I ' ,, , ~ ~ , ~ ~'-, , ~ ~ ..... .~..' .'s.",: [ ."~:"'~:~ .::.:~.: '. .~4~e ~.~ ~'.n,' : :,, .:~,~,__ ..:,.. I ' ~ ~ 2~61~ ~ ' ?H',,'h~ -' '~'ST ............. ,,5,, 10 ,~7,'H- ;;~,'' :.~,'H'.l ~ {~ . .~__'~ A,_.~. K , " ' ' ................ . , .... ~ ~. ~ .... ~ ~ ~ ~. ,, ~-~. ...... 'I ........ ';: ' " ~4n PI ~P ~ LP BP A H A ~ ~ ~4 a ~ P B P A~CO 1.;)~ Pl,~l - ~gE ............. ~Z~' i' ~ ,~-,o-,~ : t ' ~ ~~ : ....~ I I i i i iiii M~'~ ST© ~ ................. ~- ~ ....... ?..~'. ......... Z::___" ...... t~~° ....... ~...._t~? ......... Z? ......... F~::.~.~_..'..~..~ ........ ~.:'.: ........... h:'". ..... "~.':'_._L'.~_L ? , .... Z'=..._.~ .... ~__~,.:= ............ ~_. Z ........... > ~.~. ............ ~ ~ ~ ....... '~ ~ ~ _, ~ ~ ~ ~ ~ I 0 , KADLER S~ ' ......... _ ................................................................................................................................ ~ ................ ; ................... - . i I lex T£XACO 3N ISN BP BP ~LASKA INC ARCO ATLANTIC RICHFIELD A H ARCO HU~BL~ A~ H AMERADA HESS el C~a? ~ i o n ~,~ S,,' C, ~y S CeNTLIITAL OIL SUN OIL C II[S S[i~ ~ P' ~81C PHILLIPS ~c ~ ~ ~9~IL PHILLIPS 2 N 12 N r' Am GEIIB ~L ~0 SO MOBIL SOCAL PENN -- PENNZOIL ~P ARCO BP ALASKA ARCO S. O.-- B, P, SAG RIVER WELL N TIIN 0 WELL WITH OIL X SANDS ABSENT OR WATER-BEARING TION SAN D POOL T9N ~ ~ ~ SCALE ~ MILES PUT RIVER WELL AREA COVERING PRUDHOE BAY ALASKA-NORTH SLOPE PRUDHOE BAY AREA ~ m - --- ~ ~ iIC I1: ~ lie 'liN T9N ,,~ ~, .,,,,aT ~!/"' '"'"'~ -- ............ ~~' ............... T ........ ~ ................................................... ~ .......... ' ......................................................................................... 2 '"0 ...... m A · '~"~.,.'"277~. ...... .-."":-. ....... ~L ............. mm .,11 I I /~ ii ii i i · ................................................................. 5u o zS~i~o I{eJm z~'Ol zu~az }. 28233 282"34 -' ' '~7~ 47442 474~ ........... ~I~'~'~ ......... T'- ~14~3 ........... ~ ......................... , KAY'AW ~T ~'25 ~ N ~, 'J ' m ; , t t . ~ , · .. ~ , : ~ ~' , [ 2 4 7,,~.- 4 8 7 i o~ i ~ I 'i 4 4 4/ ~/~°~°~ /, ~r ,<~ ~ ~ , ,, ' ~ · '"~ -~,, - ~,'~,, ,- ..... i;~i~"-' ,,,. ..... ~, ,,,,~ ....... ~'~'~' ,~,9.~ ,i~ ....... %'; ........ ,'~5-~', ..... ~'- ~.7 ..... /.:,~, ~ E~,~,0 2 2 4 4 8 8 4 7 ~ I I I I~ 4 4 ' 4 4, I ~1 ~/2 ~~~ ' ' ' 28289~ ~1 47471 41472 78'13 28312 ?B3~ 28,329 ~ 28328 28Y2 26345 28~4 47473 4~ 7 ~ 7 8 ,4 T~'' 3 3 4 I I 4 4 .4 4 4 2 I I .,~ " ' 5- 3 7, 5 3 7 I ~1 I 4 z 4 4 II ii 14 ~R 19-10-15 ............. mmmmmma m I ...... iQ FSi-- 3~b ~ 28335 28334 28333 ~B349 28348 3 4/533 47532 : I i .. I I .... _ ......... uo P~ I~. H IRco ~Rco .l~c! ....... .co.. s,:,-.E_!L! 1~2 ........ ~?.~ .... Ls,,, c.', s ,o ~, i~.." .... ~:. ........... E_~____ o p i u , , u ~ l . I m = , t 12 12 N I BP ALASKA INC. 2 ATLANTIC RICHFI 3 AMERADA HESS e' 4- ARCO HUMBLE 5 CONTINENTAL OIL OIL, CITIES SERVl .~ HAMILTON et, al. 7 MOBIL PHILLIPS 18 MOBIL PHILLIPS S 9 STANDARD O~L OF I0 TEXACO II UN,ON PAN AMEF 12 GENERAL AMERIC~ 1:5 MOBIL SOCAL 14 PENNZOIL 15 BP ALASKA ARC TION G-WELL WITH OI <~-DR Y HOLE OIL IN KUPARUK I-- SANDS 2-- OIL IN PRUDHO SANDS OIL IN LISBURN AREA OF PRUDHOE E FIELD TI3N iSN ~"'J"'"i-~°°°°° PRUDHOE KUPARUK RIVER 6800_' ~69 O_Q ZOoo 720O TYPE' LOG OF : :THE PRUDHOE BAY AS PENETRATED IN MOBIL OIL COMPANY S NORTH KUPARUK STATE'I~ PREDOMINANT I~,.~?I--SHALE LEGEND LITHOLOGIES MUDSTONE i///~l- SANDSTONE ! DEPARTMENT OF THE ARMY U.S. ARMY COLD REGIONS RESEARCH AND ENGINEERING LABORATORY HANOVER, NEW HAMPSHIRE 03755 CRREL-EC Mr. Thomas R. Marshall, Jr. ~ I~ Executive Secretary Oil and Gas Conservation Committee 3001 Porcupine Drive Anchorage, Alaska 99504 C.O. %1 18 December 1969 HLB .7/ ~'""-'~ / TRM -/~-/ FILE Dear Mr. Marshall: With reference to our telephone discussion of 26 November, I wish to offer the follawing comments, generated by our staff, on Atlantic Richfield 's Testimony at the Prudhoe Bay Field Rules Hearings, held in Anchorage on 13-14 November 1969. I am sorry for the delay. I do hope you find these conm~ents of value in confirming your assessment of the Testimony. We prefer not to discuss the rules with respect to location and s~cing of wells, but highly endorse Rule 5. We concur in the testimony of Mr. B. C. AnderSon (spacing density and spacing' footage, his p~ge 4) regarding emergency and automatic val~es 'and proper drilling practice. Consideration for fuel spillage from an uncontrolled well relative to permafrost degradation and to fire hazards cam~ot be over-emphasized. The potential of fires in the Arctic and Subarctic areas suggests consideration be given to intra-company and intra-agency cooperation for mutual fire aid. Much interest was shown by our staff in the testimony of R. E. Smith, Permafrost Thaw and Subsidence, particularly the casing design and possible thaw degradation near the groined surface. R.E. Smith indicates (Page 7) little or no ice lens ing should be found below 50 ft. This may not be the case throughout the North Slope. Even the gravels at Umiat are known to contain large ice masses, and if fine-grained soils are encountered~ significant ice is possible to considerably greater depths. As the later testimony of Mr. Haimila points out, the Gubik formation was built up gradually during the Pleistocene period; the inclosed UBACRREL Technical Report 199 by P. V. Sellman illustrates how ice wedges can be progressively buried. We feel the oil well drillers may be giving inadequate attention to the near-surface (0-200 ft) con- ditions in their current drilling programs. Accurate soils informatio~a ,.~ "~..-' ,,,,~ :,...~: ~ , ~,, J /,¢ ,, 2', _ , DIVISION OF OIL AND GAS CRREL-EC Mr. Thomas R. Marshall, Jr. 18 December 1969 ~ the first 100 or more feet below the ground surface is essential to the design of the foundations and the well casing. The in-situ properties of near-surface soil, rock and ice, together with sub-permafrost groundwater conditions, are needed to predict surface settlements, the potential of artesian flow around the casing, and the stresses imposed on the casing by the consolidation of the soils on thawing. At our Alaska Field Station in Fairbanks about 20 years ago we had an uncontrolled artesian well through the perma- frost. The flow from this well caused continually enlarging erosion of soil from around the casing, permafrost degradation along the drainage path, and ground surface glaciation. Artificial freezing was finally required to regain control. Unless sealed, even low pressure artesian flow around wells could introduce problems of continuing thermal degradation around the well and along the drainage path. With respect to thawing around casing, we believe the initial design steps are in the right direction, but would like to point out that such thermal analysis will (1) near the surface be highly dependent on accurate assess- ments o£ ice contents~ (2) at great depths dependent on the initial s~il temperature, and (3) must consider the interaction of more than one well. Relative to the latter, the interaction of several producing wells surfacing on one pad, irrespective of directional drilling, would be a major heating problem. While .~nitial examination, without soils information, indicates that the ARCO slip joint design should be functional, we hesitate to suggest that it be universally adopted for the entire North Slope. Such a design may be adequate for a particular area of sand or gravel overburden but may not 'be appropriate for other soil, rock, ice or groundwater conditions. Casing designs should be field evaluated. We would also like to bring, to your attention the papers on cementing casings in permafrost by Diet and Cameron and Walsh in the recently published Proceedings of the Third Canadian Conference on Permafrost (14-15 January 1969), Technical Memorandt~ No. 96, Ottawa, September 1969. It is suggested the oil companies maintain a continuous dialogue on the well casing thawing problem. In future years this may be the greatest production and maintenance problem. Producing wells in gravel pads, especially multiple wells, will not permit a natural thermal regime to develop, as normally envisioned for a road or a ventilated building L~1~,~i, ~ i ~]~ ~J~I_VJ~ION OF 011. A~D_ G~LG CRREL-EC Mr. Thomas R. Marshall, Jr. 18 December 1969 fom~dation in the permafrost areas. Under certain circumstances artificial refrigeration (with insulation) may be necessary for ground surface and/or stability; some of our personnel favor this solution for adverse conditions. Refrigerated core drilling is recommended, where necessary, to provide a means of obtaining undisturbed samples of the soil and rock, so that decisions can be based on positive information. Bedrock can contain large volumes of ice, as evidenced by the large volumes of ice in the mines at ~hyo in the Yukon Territory and at a number of other Arctic and Subarctic locations. This Laboratory has a continuous interest in the design, construction and operation of these wells and the attendant construction features and would appreciate continuing opportunity to gain available information pertaining to the North Slope development. If we can be of further assistance to you relative to this matter, please let us tauow. 1 Incl TR,199 Sincerely yours, Engineering Branch CF: Dr. Robert E. Smith Senior Design Engineer North America. Producing Division Engineering Department Atlantic-Richfield Company P. O. Box 2819 Dallas ~ Texas 75221 DWI$1ON OF 0~£ AND. GAS Clearance of C~nts en Prudhoe Bay Field Rules Hearing, Atlantic Richfield Testimo~ OCE Directorate of Civil Works ATTN: E~GCW-RL (Mr. D.F.Parsons) C0~Director 1. Mr. Richard Berg of this Laboratory ~as ia Alaska this pmst October sad ~s asked by Dr. Robert E. Smith, Senior Design Engineer, Atlamtic Richfield Company of Dallas, to attemd subject hearts, a copy of the hearts is attached for your imformation. Both Dr. Smith amd Mr. T. R. M~rs.hall, Jr., E~ecutive Eecretary, Oil amd Gas Co~serva- tio~ Committee, Amchorage, invited w~it'ten comments. 2. The hearings were circulate~ amomg cognizant US~CREEL staff members and resulted in the attached letter to Mr. Marshall with copy to Dr. Smith. Yomr approval and release of this letter ~ould be apprecisted. 2 Xncls a~ Mr. Themas ~. Nars.hm.li, 1Jr. E~m~utive ,$ae~eta~ Oil an~ ~s ~serva;tiem. Committee Am,c~ge, Alas,'~a 99501 Lieut,e~t ¢olemel, CE. C~'ing Officer and Direct:,~r DEPARTMENT OF THE ARMY IL S. ARMY COLD REGIONS RESEARCH AND ENGINEERING LABOP. ATORY P.O. BOX 282 HANOVER. NEW HAMPSHIRE O37155 OFFICIAL BUSINESS CRREL-EC F~'. Thomas R. Marshalll~ Jr. Executive Secretary 0il and Gas Conservaition Committee ~001 Porcupine Drive Anchorage~ Alaska 99501 AMEI1ADA DIVISION .~i~.~IERADA HESS CORPORATION December 12, 1969 LEGAL DEPARTMENT AIR MAIL Alaska Oil & Gas Conservation Committee 3001 Porcupine Drive Anchorage, Alaska 99501 Attention: Mr. Thomas R. Marshall, Jr., Executive Secretary Re: Conservation File No. 83 Prudhoe Bay Field Gentlemen: Although we have already made an oral statement for the record, it occurs to us that a few supplemental remarks may be called for con- cerning the evidence required to support temporary 640-acre spacing rules for the Prudhoe Bay Field. These remarks are prompted by the position take~ by Pan American Petroleum Corporation at the hearing. Public disclosure of geological and engineering information can raise many problems. The Legislature itself recognized that the public interest is served by keeping certain information confidential when it enacted A.S. ~ 31.05.030 which requires, among other things., that "reports and information marked 'confidential' shall be kept confidential for 24 months after the 30-day filing period..." We are not saying this Committee may prescribe spacing rules solely on the basis of confidential information contained in its files. On the contrary, the Administrative Procedure Act (A.S. t 44.62.570(c)) requires that the Committee's orders be supported by "substantial evidence" in the record. But let us look at the evidence submitted by the B.P.-Arco-Humble group in support of 640-acre spacing. Summarized, the evidence shows (1) the general geologic setting of the Prudhoe Bay Field; (2) the lithology of the three know~ commercial reservoirs, as indicated by verbal descriptions and example log sections; (3) the approximate areal extent of each reservoir, as indicated by the locations of wells that encountered the reservoir; and (4) the ability of one well to drain at least 640 acres without waste, as indicated by permeability data and transient pressure calculations for each reservoir. Alaska Oil & Gas Conservation Committee A~chorage, Alaska 99501 -2- This evidence is sufficient to support 640-acre spacing ou a temporary basis. Certainly this is true for the three reservoirs for which data was given. In this connection, we reaffirm our position that the Committee's order expressly be made temporary for a specific period (for example 24 months, which would coincide with the confi- dentiality period for all of the wells drilled to date). Moreover, the Committee may prefer to limit the spacing rules only to the three know~ reservoirs -- although we think this would be unnecessary. In closing, we simply want to re-emphasize the importance of what the Committee does in this case -- not Just because of the importance of the Prudhoe Bay Field, but because of the impact the procedures established here will have on the future of oil and gas conservation in the State of Alaska. Very truly yours Thomas W. Lynch TWL: dj s DJVI_,tION OF OIL AND GAS L LLF227 t:--'__ PSi 5 EXT;:~A h.'U.>.( LOS, A~':GELi::S u.~LIF'"^ 12 l13;P P~T KLV HWK ~'onn:LL, ~ t:,I0. '~F nil /~['..~D c~. S RE[ IT IS THE OPI~J!ON OF U['~IOI'.; .OIL CO.~,:PAbiY OF' CnLTFO. T~i',iIA TH~-,T I",,ISUFFICIE~'~ ........ ,.. ~,r.~ O:~JECT TO a i".i~y CNA"~a ,, ~..~_ T,qRT THE ~'XHI~,ITS SPX'C!FYI. NS THE HORT,tO:.,~TAL LI ITc .... _ ,.-~u. POcE,... ,., PF~Uu]..!O~'?~.. ~.,,.,~Y -. , .... ::., h'E POOL Ai'~.'_: P'i:~,UDHOE ~g.y vUPAnU~( ...... ~ .... TO OEFINE E,.,iTH::,R 'TH ~ i<,T b ,-t~-, RY UNION OIL CC OF CALIF LOS: ¢,i'(~3ELES C,¢,LI'F ¢"7 "2 o,.~ 3 ':-" - '"' 5 ( 1 ?:5 ). DEPARTMENT OF NATUP~L RESOURCES DIVISION OF OIL AND GAS Alaska Oil and Gas Conservation Committee Conservation File No. 83 Re: The motion of the Alaska Oil and Gas Conservation Committee to hold a public hearing to hear testimony to determine the proper pool rules for the Prudhoe Bay Field. Statement of BP Alaska, Inc. Following the hearing of November 13th and 14th, 1969, protests or objections to certain of the proceedings and certain of the rules proposed by BP, Atlantic Richfield, and Humble have been filed and made a part of the record. It is the purpose of this statement to respond to points made in those protests and objections. At the outset the proposed rules, and the hearing itself, must be put in context. Prudhoe Bay field is in the very early stages of development. It covers a large area and the present drilling density is low. BP and Arco-Hurmble each have large blocks of leases in a central location and other operators hold smaller blocks in the area of interest. BP and Arco-Humble have acquired 'the greatest amount of information about the field and, though the information is far from complete, they are in the best position to plan the future development. They also have the greatest stakes in seeing to it that efficient, safe operations are required in the area. It is recognized that an inefficient practice employe~ by another operator with relatively little knowledge of the area may force BP and Arco-Humble to employ the same practice many times over in order to obtain their fair share of production. By the same token, an unsafe drilling or operating practice employed by another operator~ which results in a serious problem such as blow-out, will affect BP and Arco-Humble to a magnified degree. The Prudhoe Bay Field Rule Hearing was called by the Committee on its own motion. The main point of the proceeding is to establish rules for the develOpmen~ of the field. Production is two or more years away and problems associated with it may be resolved later when additional reservoir data and other information is available. Within this factual setting we turn to the controlling statutes and regulations. The hearing was held under Section 2004 of the Oil and Gas Conservation Regulations. This section implements and interprets AS 31.05.100, among other sections of the Oil and Gas Conservation Act. AS 31.05.100 provides for the establishment of drilling units for pools, that is, it provides for the adoption of spacing patterns for pools. This authority is also referred to in AS 31.05.030 ~) (3). Section 2061 of the Oil and Gas Conservation Regulations is the basic implementation of this authority. It provides a so-called "statewide rule" for spacing oil wells on 160-acre pattern "in the absence of an order by the Committee establishing drilling units or prescribing a spacing pattern for a pool." The section begins~ however~ with the following sentence: "In proven oil and gas fields, the establishment of drilling units and a spacing pattern will be governed by special field rules adopted in accordance with section 20004." It was for this purpose that the hearing was called. Section 2004 of the Oil and Gas Conservation Regulations actually discusses two categories of regulations: 1. After discovery~ " . . . the Committee shall issue an order based upon the evidence presented prescribing any necessary field rules for the development of t~'e pool." · 2. For operation of and production from the pool, if the Committee finds that pool rules are necessary to prevent waste and to protect correlative rights, it may adopt rules, allocate production, classify the pools as oil and gas pools, and so forth. The language of the regulation distinguishes between the field rules required at the development stage and the detailed pool rules required for operation. The Oil and Gas Conservation Act and the regulations implementing it recognize that often the physical characteristics of a field or pool cannot be known to a certainty. Thus, for instance, "field" is defined as "a generaI area which is underlain or appears to be underlain by at least one pool and includes the underground reservoir containing oil and gas; .... " Similarlyr "pool" is defined as "an underground reservoir containing, or appearing to contain, a common accumulation of oil or gas." (AS 31.05.170(4) and (9)). One commentator has clearly set forth the nature of proceedings of this sort and the philosophy most logically adopted: It must be remembered that, in the entry of a well spacing order, the regulatory agency is not adjudicating rights, but rather is regulating production. This is an important distinction. [Citation omitted] If the agency were endeavoring to adjudicate and the decision entered were final and binding with the res judicata effect of a judicial decision, it would be required to obtain the complete facts and space the field once and for all. It could neither favor wide nor narrow spacing as a matter of policy. However, where a Commission is regulating and may modify its regulations as additional information becomes available, the approach can be different. Sometimes a petition for a well spacing order comes so early in field development that --3-- definitive evidence simply is not available. The testimony consists largely of the conflicting opionions of geologists and engineers as to what the field will do when it is produced. The Commission may not be convinced from the evidence presented that the requested spacing will be proven to be correct when the field goes into production° However, since the Commission is only regulating and may change its regulations,_it may safely require wide spacing on a prima facie showing that this will probably drain the field efficiently, although the Commission may not be convinced that it assuredly will do so. Then, after the field goes into sustained production and more definite indications of proper spacing become available, infill wells can be permitted, if necessary. If the Commission, on the other hand, were to resolve the initial doubts in favor of close spacing and thereafter it was proven to be wrong~ the error could not be corrected. (Clyde, Problems of Regulatory Agencies~ 7 Rocky Mountain~ Miner'al Law InstitUte at p'. 181 (1962)). See also Williams, Nature ~and Effect of Conservation Orders, 8 Rocky Mountain Mineral Law Institute, 433 (1963), emphasizing the legislative nature of conservation orders and their susceptibility to prospective amendment. In this connection it should be noted that one of the operators protesting this proceeding seems to imply that in acquiring a lease upon payment of a substantial bonus it acquired a right to operate under rules and regulations as they were at the time of issuance of the lease. It is perfectly clear that no such right was acquired and the lessee is subject to valid exercise of the police powers of the State of Alaska as expressed in the Oil and Gas Conservation Act. See Section 20 of the Lease Form DL-1 (Oklahoma Natural Gas Company vs.' 'Long, 406 P.2d 499; Simmons vs. Pure Oil Company, 124 S.2d 160 (La. 1960). It has been suggested in one of the protests filed in this matter that a hearing under the adjudicative provisions of the Alaska Administrative Procedures Act (AS 44.62.330 et seq.) ought to have been held. No showing has been, or can be, made that an adversary hearing is required. There is nothing in those sections of the Alaska APA requiring adherence to the trial-type procedure when the agency is engaged in rule making, a quasi-legislative function. If the Alaska APA were to apply at all, it might require employment of the procedures for adopting regulations. The Prudhoe Bay Field Rules however, are obviously not rules of statewide application and need not follow the APA. This is specifically recognized in the 1969 amendment · to AS 31.05.050 which~ in subsection (b), distingUiShes procedures "concerned only with operations on a single well or within a single field," and exempts them~from APA requirements. It might be noted here incidentally, that it is equally clear that establishment of 640-acre spacing is not an "exception" to the statewide spacing rule foUnd in Section 2061 of the Oil and Gas Conservation Regulations. An "exception" which might call for a higher degree of proof in justification, is a variation from "section 2061 or any spacing order of the Committee". The Committee is here concerned with the establishment of spacing for a particUlar field which is tailored to the requirements of the field at this time° While this proceeding is not held under the Alaska APA, it may be useful to compare this proceeding and the standards to be employed with the case law of California relating to its APA, which was the model for the Alaska Act. A leading case in this area is Brock vs. ~Superior Court, 241 P.2d 283 (Cal. CA 1, 1952). The Director of Agriculture acting under the California Marketing Act, adopted a marketing order for a specific agricultural product. In many ways the nature and functioning of orders of that sort are analogous to oil and gas conservation orders. The coUrt held that the adoption of such an order was a quasi-legislative function, citing Ray vs. Parker, 101 P.2d 665. A hearing was held on the proposed rule which was apparently very similar in form to the November 13-14 hearing held by this Committee. Statements and testimony were given and exhibits were submitted, but it was not a trial type hearing. (In other cases the California courts have held that "the ascertainment of facts in its essence is not a legislative function. It is simply ancillary to legislation." Parker vs. Riley, 113 P.2d 873 quoted in Vita-Pharmacals vs. Board' of Pharmacy~ 243 P.2d 890.) The court in Brock discusses at length the evidentiary standards to be met by the agency and the scope of reView of the courts It holds the scope of review to be substantially more limited than is the case if the agency is performing a quasi-judicial function. The court holds that "the de novo type of review does not apply to quasi-legislative acts of administrative officers and that the judicial review is limited to an examination of the proceedings before the officer to determine whether his action has been arbitrary, capricious, or entirely lacking in evidentiary support, or whether he has failed to follow the procedure and give the notices required by law." (At page 290)° The case has been cited with approval.in 'Vita'-pharmacals suPra and elsewhere. In the same vein, it has been held that the court is to determine the legality of the regulations, not their wisdom. Morse vs. Williams, 433 P.2d 697 (Cal. 1967). The Williams article referred to above (Nature and Effect of Conservation Orders, 8 Rocky Mountain Mineral Law Institute, 433 (1963)) covers judicial review of conservation orders at some length, citing many cases. While state statutes vary, it seems clear that the generaI rule is that Commission findings within its jurisdiction will not be disturbed in the absence of clear error. This seems to be often true despite statutory authority in some states for the courts to take additional evidence and to substitute their judgment for that of the Committee. Alaska's recent Pan ~erican vs'.~ ~Shell, 455 P.2d 12, in which the Court refUsed to permit the Superior Court the full breadth of reView prescribed by the APA makes it apparent that Alaska'a Court will concur. The bulk of the objections raised by those filing protests in this hearing fall by the wayside when it is recognized that no adversary or trial type hearing is required in this matter. It is well-known that strict rules of evidence are not to be applied in administrative proceedings~ even under the adjudiCatory provisions of the Alaska APA, and questions such as best evidence, burden of proof, foundation for testimony~ all fall by the wayside when it is remembered that this Committee is "legislating". It is not bound to formulate issues in advance of the hearing as a trial court might any more than a congressional committee is required to do so. It is not required to act on the basis of any specific degree of proof. While the Committee is bound to act reasonably and while the orders of the Committee cannot be so lacking in evidentiary support as to be arbitrary or capricious~ it is not held to any sort of mathematical standard or formula in weighing the evidence presented. It is clear that in any review proceeding, the burden of establishing the invalidity of an order is on the appellant. At the present state of knowledge of the Prudhoe Bay Field this is an extremely difficult burden. The philosophy expressed by Clyde supra is again pertinent: Field rules established early in the development of a field may be based on less than complete knowledge, with the realiZation that additional information may require revision. The realistic ~7-- approach in that situation is to adopt rules which can be effectively modified when desired° It is hard to picture a basis upon which the court would overturn rules adopted on that principle so far in advance of actual production. ELY~ GUESS, RUDD & HAVELOCK Attorneys for BP Alaska, Inc. Operator for BP Oil Corporation Joseph~ -.,% -8- Alaska Oil and Gas Conservation Committee 3001 Porcupine Drive Anchorage, Alaska 99504 December 5, 1969 83 - A Attention: Mr. Thomas R. Marshall, Jr. Executive Secretary Gentlemen: Re: Conservation File No. 83 - Motion of the Alaska Oil and Gas Conservation Committee to hold a public hearing to hear testimony to determine proper pool rules for the Prudhoe Bay Field Pennzoil United Inc., as Operator for a group consisting of several companies including Colorado Oil and Gas Corporation, by letter dated November 26, 1969, advised the Committee in a general manner their understanding of the position of the group. Colorado is filing this letter individually in order that the Committee may clearly understand the position which Colorado takes in regard to the proposed field rules which were presented by Atlantic Richfield Company on behalf of itself and other designated parties. Colorado owns a substantial varying interest in several leases which were acquired by the Pennzoil group at the State sale held Septem- ber 10, 1969. Three of these leases are included in the proposed area for the Prudhoe Bay-Lisburne Pool. This company feels that the rules and regulations in effect at the time its interest in these leases was acquired by it should govern the exploration and development and producing operations on the lands covered by said leases and that these rights should not be taken away or restricted without sufficient pertinent evi- dence, tested by cross-examination, being presented at a full and complete hearing. Colorado has been furnished a copy of the Protest and Demand for Hearing which was prepared and filed by Pan American Petroleum Corporation and Union Oil Company of California in regard to these same matters and does herein endo~rse fully the positio~taken by those companies in the said Protest an~.~Demand for Hearing. i~!~ RECEIVED' -. Respectfully submitted, ~lw_sloN oi~ ANCHO~AGS JRC: cbg j cc - Pennzoil United, Inc. Attn: Mr. James A. ~vidson P. O. Drawer 1828 Midland, Texas 79701 MARATHON OIL COMPANY PRO(2)U(CTIC)N - UNITF=C) STATI=S ANED (CANAOA LOS ANGEl_ES OlVISION L. P. FOOTE, MANAGEFI 550 SOUTH FLOWER STREET FILE. LOS ANGELES, CALIFORNIA 90017 November 28, 1969 Mr. Thomas R. Marshall, Jr. Executive Secretary Alaska Oil and Gas Conservation Committee 3001 Porcupine Drive Anchorage, Alaska 99504 Re' Conservation File No. 83 Prudhoe Bay Field Dear Mr. Marshall' Enclosed is the Statement of Marathon Oil Company relative to the hearing held on November 13 and 14, 1969, in Conservation File No. 83 concerning the Prudhoe Bay Field Rules. Please file this statement in the record for Conservation File No. 83. Yours very truly . .~.~~--~/~'~"__'~~ ,,/ L. P. Foote Division Manager LPF/la Enclosure CONSERVATION FILE NO. 83 STATEMENT OF MARATHON OIL COMPANY Marathon Oil Company is the holder of various interests in certain State of Alaska oil and gas leases within the area proposed in the hearing of Conservation File No. 83 to be covered by the Prudhoe Bay Field Rules. In general, Marathon supports the rules proposed by the Arco-BP presentation at this hearing except as modified by this statement of Marathon's position. Marathon concurs with the statement made in behalf of the Hunt interests and Placid Oil Company at this hearing. In particular, Marathon recommends that further study be given to the application of Conservation Committee Rule 2159 to the production of gas cap gas from pools located within the area proposed to be covered by the Prudhoe Bay Field Rules so that upon a further hearing on this subject as proposed by the Committee a rule may be promulgated which will adequately protect the correlative rights of the parties and prevent waste or dissipation of pool reservoir energy. Marathon is in accord with the suggestion of the Chairman of the Conservation Committee that the rules issued as a result of this hearing be specifically designated as temporary rules pending the acquisition and publication of additional data from the area concerned. ,~'" '~ i,,i ' "..'i" ~:'~'" Statement of Marathon Oil Company Page Two Marathon further suggests that the application of these field rules be expressly provided to be temporary as to undefined or subsequently discovered pools within the field area for a period of one year or for a lesser period of time if a hearing by the Conservation Committee for such pool is held within that year. As to Rule 3 proposed by Arco-BP, Marathon strongly concurs with the purpose of this proposed rule. Due to the extremely difficult operating conditions in the area an operator should have the flexibility of well location provided by such a rule. The distances requested are equivalent to those provided for oil wells by Conservation Committee Rule 2061, therefore, would not be considered to be contrary to good conservation practices. Further, this rule would be conducive to the prevention of waste by tending to lessen the amount of footage required in directionally drilled wells and should also lessen any permafrost problem by having shorter drill depths as to many of the wells. As to unitization of the Prudhoe Bay Field area, Marathon is in accord with the other owners of interests in the area that appropriate unitization should be effected at the earliest possible time. Early unitization appears necessary to provide for the orderly development and operation of the area. Marathon has been asked to participate in negotiations Statement of Marathon Oil Company Page Three for unitization within the area and will be glad to participate in such negotiations toward the objective of unitization on a fair and equitable basis. MARATHON OIL COMPANY - L.' P: Foote Division Manager DIVISION OF 01[. AND G/~$ PENNZOIL UNITED WESTERN DIVISION OFFICE · WALL TOWERS WEST - MIDLAND, TEXAS · PHONE (915) 682-7316 MAILING ADDRESS: P. O. DRAWER 1828 MIDLAND, TEXAS 79701 November 26, 1969 Alaska Oil and Gas Conservation Commission 3001 Porcupine Drive Anchorage, Alaska.99504 Attention Mr. Thomas R. Marshall, Jr. Executive Secretary Gentlemen: Re: Proposed Pool Rules Hearing, November, 1969 Prudhoe Bay Field (AO&GCC File No. 83) Reference is made to proposal dated November 13, 1969, made by Atlantic Richfield Company regarding the above cap- tioned matter. Pennzoil United, Inc., as operator for the group con- sisting of itself, .Al-Aquitaine Exploration Ltd., Forest Oil Corporation, Colorado Oil and Gas Corporation, and Newmont Oil Company agrees in principle to wide spacing but it is our opinion that a decision to adopt 640-acre spacing as proposed by Atlantic Richfield in Rules 1, 2 and 11 should be withheld until such 'time as all information is made available to the in- dustry or additional information is obtained from future drilling. We do concur with Rules 3, 4, 5, 6; 7, 8, 9 and 10 as proposed by Atlantic Richfield. This group also endorses the principle of unitization and conservatiOn of gas cap and is agreeable to discussing and ne- gotiating such parameters as would be necessary in establishing fair and equitable participation. This group also feels strongly that all presently avail- able information regarding permafrost should be made available Alaska Oil and Gas Conservation Commission Page Two November 26, 1969 to all operators as an aid in planning casing programs for orderly development of the field in keeping with good oil field practice. We very much appreciate the opportunity of making this statement. Please advise in the event that we might furnish any further information. JAD/ke cc: Very truly yours, PENNZOIL UNITED, INC. 'James A. Davidson Division Landman Atlantic Richfield Company P. O. Box 2819 Dallas, Texas 75221 BP Alaska, Inc. 620 Fifth Avenue New York, New York 10020 Humble Oil & Refining Company P. O. Box 2180 Houston, Texas 77001 Mobil Oil Corporation P. O. Box 979 Anchorage, Alaska 99501 Phillips Petroleum Company P. O. Box 419 Anchorage, Alaska 99501 Standard Oil of California P. O. Box 7-839 Anchorage, Alaska 99501 Highland Resources~; ..,c., San Jacinto BuilcJing,Houston,Texa~ (713) 223-4901 November 26, 1969 Mr. Thomas R. Marshall, Jr. Executive Secretary Alaska Oil and Gas Conservation Committee 3001 Porcupine Drive Anchorage, Alaska 99504 TRM ~-~ OKG KLV FILE ...... Dear Sir: Highland Resources, Inc. concurs with the proposal of Atlantic Richfield Company, BP Alaska Inc., and Humble Oil & Refining Company to establish temporary Well spacing rules of 640 acres per well for each of the three producing pools in the Prudhoe Bay Field Area for initial development. A rehearing after more complete data are available will no doubt be de-. sirable. Three questions are raised, however, with respect to the testimony and exhibits of certain Atlantic Richfield Company and BP Alaska, Inc. witnes- ses~ (1) In the event that'additional subsurface information indicates faulting or other situations which would create appreciable, dif- ferences in reservoir characteristics, provisions should be re- tained for separate field designation. (2) Although the tw° methods suggested for contention with permafrost thawing conditions around individual well bores appear at this time to be sound, we agree with both witnesses that other methods which are under study might prove equally or more efficient and effective. We strongly urge that the committee continue tore- view other sol'utions to this problem as they are proposed. (3) Highland Resources is in favor of fieldwide unitization on a fair and equitable basis as soon as possible and therefore requests -It} Mr. Thomas R. Marshall, Jr. -2- November 26, 1969 that all operators in the area of interest be included in the unitization efforts initiated by Atlantic Richfield Company, BP Alaska Inc., and Humble Oil & Refining Company. Yours very truly, / , R. P. Haddox Vice President RPH:fb Mobil Oil Corporation Alaska Division of Oil & Gas 3001 Porcupine Drive Anchorage, Alaska 99501 Attention: Homer L. Burrell Director Alaska Division P. O. Box 1734 Anchorage, Alaska 99501 November 19, 1969 PRUDHOE BAY FIELD RULES HEARING - NOVEMBER 13: 1969 Gentlemen: Attached you will find a summary of, and supporting data for, the well completion procedure which, subject to your approval, Mobil Oil Corporation plans to use for future producing wells in the subject field. Testimony pertaining to this technique was not presented at the subject hearing since the planned procedures will fall within the existing Statewide Rules and Regulations or the methods proposed at the hearing by Atlantic-Richfield or British Petroleum. Mobil Oil Corporation would again like to state concurrence with the Prudhoe Bay Field Rules proposed by Atlantic-Richfield and British Petroleum. It is again emphasized that there is insufficient infor- mation available at this time to enable a valid estimate of what the ultimate well spacing should be in any of the productive pools in this field. Testimony was presented at the subject hearing in support of 160 acre spacing for the Kuparuk River Pool. One of the prime arguments purporting to justify 160 acre spacing was an extremely long estimated producing life. This long life was based on certain assumed conditions for initial and economic limit producing rates and oil originally in place, and included a 40 percent recovery. The same recovery was utilized regardless of the assumed recovery mechanism (fluid expansion, solution gas, or water drive). It is believed that under a solution gas or combination fluid expansion - solution gas recovery mechanism a more realistic recovery would be in the range of 10 to 20 percent. Utilizing the same conditions, the producing life would be reduced approximately porportional to the reduction in recoverable'reserves. Under a water drive mechanism, either natural or induced, higher producing rates could be anticipated for a longer period of time and the ultimate life could be varied appreciably depending on when it is assumed that an exponential decline would begin. -il - 2 - The other item advanced in support of closer spacing for the Kuparuk River Pool was the possibility of lenticular sands and that 160 acre spacing would be required to ensure optimum drainage of all lenses. It is not believed that there is sufficient control at this time to establish the degree of lenticularity or that the sands are not interconnected. Additional drilling on wide spacing is first needed to obtain information which will enable a better evaluation of optimum spacing. In summary, Mobil Oil Corporation recommends adoption of wide spacing for initial development of all reservoirs in the Prudhoe Bay Field. Later development on closer spacing may prove necessary, However, the ultimate spacing should be dictated by information obtained while developing the various reservoirs initially on wide spacing. Very truly yours,. C. C. W~ Division Engineer ~.LV!SlON OF OIL AND COMPLETION PROCEDURE FOR FUTURE MOBIL OIL OPERATED NORTH SLOPE WELLS Introduction The discovery of oil in Arctic regions has introduced many new and unique problems which must be successfully dealt with before that oil can be brought to market. One serious difficulty anticipated is the thawing of the permafrost around the producing oil wells in these regions. This thawing is caused by the production of large volumes of hot fluids (possibly 200°F bottomhole temperature) for extended periods of time. Any thawing that occurs at the cement-permafrost interface will destroy the cement bond. Thawing of the permafrost in the upper layers near the surface will result in sloughing of the soil around the wellbore. The ensuing mechanical stresses imposed on the casing could result in irreparable damage and necessitate premature abandonment of the well. In view of the tremendous drilling and completion expenses encountered in the Arctic, this is obviously highly undesirable. There are two possible approaches to solving this problem. One is to prevent thawing of the permafrost through a section thick enough to maintain a competent well completion. The other is to allow permafrost thawing and design a well completion which will be compatible with the adverse conditions resulting therefrom. For the first of these solutions there are again two possible means for accomplishing this goal. One method is to adequately insulate the production string through some portion of the perma- frost zone. The second method is to refrigerate the casing string through some portion of the permafrost zone. I. HIGHLIGHTS OF MOBIL'S PROPOSED NORTH SLOPE COMISLETION EQUIPMENT A. OBJECTIVE' To describe the completion procedure and the equipment associated with it for Mobil Oil-operated North Slope wells to be drilled in the future. B. SUMMARY OF KEY COMPONENTS 1. ,30-inch O.D. pipe will be run to 40+- feet in 36-inch hole and cemented to the surface. 2. 20-inch O.D. casiog will be run to 700+- feet in 24-inch hole. Only the lower 200 feet will be cemented. An ocean bottom sus- .pension type hanger seat will be .run in the 20-inch string and located at 500+- feet. ' 3. 16'inch O.D. casing will be run in 20-inch hole to 3000 feet. It will be hung at 500 feet in a subsea type suspension system and cemented. Excess cement will be circulated out of the hole above the hanger and the upper 500 feet of annulus will be left liquid filled. ' 4. 7-inch O.D. casinq will be run to T. D. This will. be the pro- duction flow string. It will hang in the 16-inch at 1500+- feet. Cement will be circulated from above the tie-back sub and then the liquid in the 7-inch x 16-inch annulus will be removed, leaving the upper 1500 feet of annulus air filled. The upper 7'00 feet of annulus will be insulated with extruded polyurethane foam. 5. The 16-inch x 7-inch casin~ head housinc[ will have dual pack-offs to allow the 7-inch to "grow" as it produces hot well fluids. 6. 3½-inch O.D. tubing will be run'in the hole to some depth above T.D. A dual hydraulic-set packet' and Otis dual-flow nipple will be run on this string. The 3½-inch tubing will be used to produce through and can be used to kill the well prior to working over. The dual-flow nipple will contain two wireline retrievable ball safety valves. C. ADVANI'AGES OF THIS COMPI.ETION SYSTEM 1. Tried and tested completion componer~t:s can be used. 2. Subsidence and foundation problems due to melt:ing of permafrost will not occur since the upper 500 feet of permafrost will not thaw. - 2 - 3. The insulation can be repaired or replaced during the producing life of the well. 4o The weight of the casing and tubing is transferred to the ground downhole and does not go through the wellhead° 5° Safety valves provide conventional backup protection downhole where the formations will be competent. 6° This system is compatible with the existing statewide rules or with the use of slip joints in the 20-inch casing° 7° Refrigeration can be added as a supplementary measure anytime during the life of the well. Do LIMITATIONS 1. The insulation must be kept free of contact with liquids during the life of the wello 2. The well must be killed and the tubing pulled before the upper portion of 7-inch casing can be pulled to repair or replace the insulation° 3° Two hydraulic lines will be required to operate the safety valves at the depth they will be located. - 3 - II. DESCRIPTION OF COMPLETION PROCEDURE -- The key to this completion system is that the upper 500 feet of permafrost will be prevented from thawing by insulating the upper 700 feet of the flow string° The intermediate casing string will be 16-inches O.Do rather than the conventional 13-3/8-inches OoDo in order that the required thickness of insulation can be installed° Forty feet of 30-inch conductor will be set and cemented to the surface as has been the conventional practice in the area° (See Exhibit A) The casing and~:t~bing sizes shown here are for illustrative purposes and can be altered to fit the individual situation. The present plan calls for 700 feet of 20-inch OoD. casing to be set. The lower 200 feet will be cemented using a duplex shoe. The annulus between the 26-inch borehole and 20-inch casing from the top of the cement to the surface will be filled with gelled drilling mud or gelled oil. A subsea suspension system seating nipple will be run in the 20-inch casing string at 500± feet° The depths of the 20-inch and the seating nipple will be altered if future infor- mation indicates they should be° The heart of our completion system is the intermediate casing string which will be 16-inches O.D. rather than the more conventional 13-3/8-inches O.Do The larger internal diameter of this casing will allow required thickness of insulation (2-3/4-inches) to be run° This casing will be run to a depth of 2200± feet° It will be hung in the subsea hanger assembly at 500± feet° It will be cemented, using a duplex shoe, from the bottom to above the subsea hanger° After the cement is in place, ports will be opened up above the hanger and the excess cement will be circulated out and replaced with gelled drilling mud or .... , %,, ...... · gelled oilo The circulation ports will then be closed° -4- The 7-inch O.D. casing will be run to ToDo This casing will be used as the primary production flow string° It will be hung on a liner hanger or a subsea hanger at about 1500 feet° The productive zones will be protected by stage cementing° One stage of cement will seal the 16-inch x 7-inch annulus to above the subsea hanger° The circulation ports in the tie-back sub above the subsea hanger will be opened and any excess cement circulated out. The cement seal will be pressure tested and then the liquid will be removed from the annulus above the circulation ports° The tie-back sub will be released and the upper portion of 7-inch casing removed from the holeo This upper portion of the 7-inch casing will be rerun (in the air filled upper portion of the hole) with 2-3/4-inch thick extruded polyurethane insulation strapped to it. The depth of insulation will be 700 feet° Our calculations show that this insulation will keep the upper 500 feet of permafrost from thawing at a flow rate of 25,000 B/D through the 7-inch casing° The 16-inch x 7-inch casing head housing will incorporate a double seal pack-off assembly of the type used in steam flood wells° (See Exhibit B) A polished nipple will be placed in the casing string located to pass through the seals° This will allow the 7-inch casing to "grow" in relation to the 16- inch casing as the hot well fluids are produced° No expansion joint or slip joint wellhead will be needed between the 7-inch casing and 3 l/2~inch tubing ~eea~me the two strings will be the same temperature and will therefore expand the same amount° The 3-1/2-inch tubing will be run into the hole after the well is perforated° An Otis dual-flow nipple will be run on the tubing above a dual hydraulic-set packer. The dual-flow nipple will house two wireline retrievable ball safety valves° The packer and safety valves will be set below 1500 feet° This will provide the conventional back,up safety equipment at a depth where the formation - 5 - is competent. The 3-1/2-inch tubing can be used as a fill string to kill the well prior to working over. It also will be produced through when maximum production is desired. This completion technique can also be used in compliance with existing statewide rules which require cement to be returned to the surface outside the surface casing~ It also is compatibt~ with the use of 20-inch slip joints° Refrigeration can be added at any time during the life of the well by reducing the thickness of insulation and hanging an open ended string of 13-3/8-inch O.D. casing° - 6 - :' III. GENERAL DISCUSSION OF THERMAL cALcULATIONS. -. A mathematical model has .been developed here whic~ can predict the' extent to which thawing will-occur iff uhprotected Wells and'can evaluate the effectiveness of various schemes of insulating the production string. A description of this model and some of the results obtained with it are des~r'ibed in this memorandum. .. Description of the Model The flow of heat in the earth surrounding the well is assumed to be radial and axial. The temperature distribution in a cylinder surroundTng the wellbore is given by where H = H(T). f · The boundary conditions for this cylinder are T (r,O,t) = T (.r, zb, t) : Tb ~'.( z t) : 0 (4.) The remain?ng boundary conditTon~ the temperature at the earth - well interf~ce~ iS found from the following energy balance written for the fluids inside the well tubing: fGc~f gTt- 2--U (Tt ' Tw): ~PC~f 6Tt ~ - ' r - (5) : T( z,t), whe re Tw rw, .., :: BT Urt(Tt-Tw) : 'kr rw~rr and Tt : T(O,z~t) . r~- rw .~ 11969 piy. l~lON OF OIL AND_ QAS (6) (7) (8) - 7 - The initial temperature distribution is a function of depth and is given by T(r,z,O) : Tb - m(zb - z) (9) The thermal conductivity of the earth may have a radial component which differs from the axial component and each of these components may vary as functions of r and z . ~H The change of enthalpy with respect to time, ~-~ , in Equation I is calculated in such a way as to include the heat of fusion of water when the ice melts. The details of the treatment of this aspect of the problem are given in the following section. The solution of Equation 1 is accomplished digitally from a finite difference representation of that equation. The finite difference techniques and the solution algorithm are described in a subsequent section. Calculation of Enthalpy Chanqe Figure 2 shows schematically how the enthalpy of water depends on its temperature. The slope of the curve left of the freezing point, 32°F, is I 32°F T Figure 2. Enthalpy of Pure Water the heat capacity of ice; the slope of the line to the right of 32° is the heat capacity of water. The height of the discontinuity is the latent heat of fusion. Figure 2 represents the enthalpy of pure water. The water making up the ice in the permafrost will be impure to some extent. This fact~ along with capillary suppression of the freezing point, causes the ice to melt over a finite temperature range. In this case its enthalpy would resemble the curve given in Figure 3. T Figure 3. Enthalpy of Impure Water The heat capacity, based on Figure 3, is now continuous and equal to the slope of the curve at any temperatUre. Such a heat capacity is shown in Figure 1. Figure 4. Heat Capacity of Impure Water If we assume the behavior shown in Figures 3 and 4, we can represent the enthalpy derivative by ;~H = ~H ~T = C (T) ~T (10) where C (T) is a continuous function of temperature. P For reasons discussed later~ it is convenient to express enthalpy versus temperature by three straight line segments, as shown in Figure 5. The resulting heat capacity is shown in Figure 6. Figure 5. Assumed Enthalpy C P i T Figure 6. Assumed Heat Capacity - lO - It is no longer continuous, but it is piecewise continuous -- in fact, piecewise constant-- and always finite. Equation 10 is still valid. Using a heat capacity as shown in Figure 6, we can approximate melting over a range of temperatures or~ by narrowing the freezing band~ come very close to approximating the melting of pure water. There is a limit to how narrow the band can be. If it becomes too small, numerical roundoff errors will cause problems. We used a melting range of several degrees here because it suited our purposes. Though we did not verify it~ we believe that we could have used a range of 10-4 degrees or less without any problems. Accumulator Cemenf ~oft. I~ottom ~f insulation ?00 ft · 500 ft · Cement lower 200 ft 700 ft 16" x 17"mud line suspension at 1500 feet 2200 ' Se! DV tool below 16-inch casing shoe (Alternate A ) "'" o Kuparuk River ~- - Formalion Pruc,~oe Bay Sand ! Pruahoe Bay - j- · . Hydraulic t,%nifold' · Hydraulic .Control Line . · Hydraulic Balancing Line 30" Csg. ~ 40 · . . Insulation' (7- inch. I.D. x 12~--incP O. 20''x 16" g~ud Line SuspensiOn 20" Csg. ~ 700' . . 3~' E.U. Tbg. i ~' ' 7"x 3" 3" x Dual Nipple Assembly · 3" ' 7 i, x 1~' .Ball' Safely Valve J · i, Dual-Hydraulic set Packer (Hydraulic Holddown) . . 16" Csg. ~'2200 Set D.V. tool below Kuporuk ~ve~ Formation (Alternate B) ,~ 7"Csg. ,~TD .. . 1. 875 "N" Nipple No-Go I.D. - 1.791 EXHIB l'r A jCOMPLETION PROGRAM J for Mobil Oil i j North SloPe ~?ells j' ANCHORAGE DAILY NEWS November 29, 1969 :Alaska' Oil and Gas Conservation 'COMmittee her_,qbF extlmds .un~'.De-.j durtnf which it Wilt ~aeeipt' :s~tements ~or. ,the.. r, ee0rd o~: the , l~earlnar' ~ ".hem ,~i~.t~To~e~ber. IS':. to c.~n&tde~, .l~oper~O_Ql.~ea. ~r additional ,time,,< liver :,~ . Ala~$k 1. ' :Con 3~1,] ine, DriVe .,.~:,. ,' '/': ' Ankh4 Alaska '99~04~' ~ '' ~ I,S ;"', . :',":, '~:,,i,,~,'" ' '~ ": ' {,Publish:. N~.V,.,,'~,,,: 1969 ~'LelI,~l :l~otice 1~., i,Itl ,,., , Atlantif~RichfieldComparty North Ameri~."-'~ Producing Division Alaska Distr( Post Office Box 360 Anchorage, Alaska 99501 Telephone 907 279 1411 November 28, 1969 Mr. Homer L. Burrell~ Chairman Alaska Oil & Gas Conservation Committee 3001 Porcupine Drive Anchorage~ Alaska 99504 Dear Home Attached is a formal letter from B. C. Anderson providing the information which was requested concerning gravity and sulphur and wax content. Mr. Anderson reviewed the testimony and stated that he thought this would provide the informa- tion which the Committee had requested. If you want more information in this regard, I will be pleased to ask Mr. Anderson to place the material in your hands, and either you or one of the committee members can pick out what you want and put it in the record. Kindest regards. !/Y yours, Very tru Hoyt M. Cd]l)e Attorney HMC: jh Attachment c: Mr. B. C. Anderson At~i'a nticRibhfieldCom pany t"~,] ort h A,~,~eril ?roduci.0~ Alaska District Post Office Box 360 Anchorage. Alaska 99501 Telephone 907 277-5637 November 28, 1969 Mr. Homer L. Burrell, Chairman Alaska Oil & Gas Conservation Committee 3001 Porcupine Drive Anchorage. Alaska 99504 Dear Mr. Burrell: This letter is in response to the questions concerning reservoir fluid properties that the Committee asked of Atlantic Richfield and British Petroleum witnesses at the Prudhoe Bay Field Rules Hearing on November 13 and 14, 1969. Analyses of Prudhoe Bay Sand Pool fluids have been made on samples taken from ARCO's Prudhoe Bay State No. 1 well, ARCO's Sag River State No. 1 well, and BP's Put River No. 1 well. Analyses of Lisburne Pool fluids have been made on samples taken from ARCO's Prudhoe Bay State No. 1 well. To our knowledge, no analyses have been made on samples from the Kuparuk River Pool. The following table lists data which we feel is most representative of that available at this time: Prudhoe Bay Lisburne Kuparuk Sand Pool Pool River Pool Oil Gravity, o API 27.00 26.90 23.60 Reservoir Oil .69 .98 Not Viscosity, c.p. Available Sulphur Content in Crude, % Wt. 1.00 1.14 Not Available Wax Content in 6.50 Crude, % Wt. Not Not Available Available Special tests of crude from the Prudhoe Bay Sand Pool show that precipitation of wax in measurable quantities commences at 55° F, but very small quantities may precipitate at up to 85° F. Very truly yours, ATLANTIC RICHFIELD COMPANY B. C. Anderson cc: Mr. John Saint I ov 2 HAMILTON BROTICEr~S O~L 1517 DENVER CLUB EBUILDING DENVER, CiOLORADO 80~0: November 26, 1969 OKG_ ~' - KLV -.- . HW:/, REL FILE . -- Mr. Thomas R. Marshall, Jr. Executive Secretary Av,~ Alaska Oil and Gas Conservation Committee 3001 Porcupine Drive Anchorage, Alaska 99504 Dear Mr. Marshall: ! Hamilton Brothers concurs with the proposal of Atlantic Richfield Company, BP Alaska Inc., and Humble Oil & Refining Company to establish temporary well spacing rules of 640 acres per well for each of the three producing pools in the Prudhoe Bay Field for initial development. A rehearing in approximately 18 months after effective date of order would permit the gathering of more complete reservoir information for analysis prior to the establishment of permanent field rules. Three questions are raised, however, with respect to the testimony and exhibits of certain Atlantic Richfield Company and BP Alaska, Inc. witnesses: (1) In the event that additional subsurface information indicates faulting or other situations which would create appreciable differences in reservoir characteristics, provisions should be retained for separate field designation. (2) Although the two methods suggested for contention with permafrost thawing conditions around individual well bores appear at this time to be sound, we agree with both witnesses that other methods which under study might prove equally or more efficient and effective. We strongly urge that the committee continue to review other solutions to this problem as they are proposed. (3) Hamilton Brothers Oil Company is in favor of fieldwide unitization on a fair and equitable basis as soon as possible and therefore requests that all operators in the area of interest be included in the unitization efforts initiated by Atlantic Richfield Company, BP Alaska Inc., and Humble Oil & Refining Company. Yours very truly, FFH / in HAMILTON ~HERS OIL COMPANY ~erris~'Ha~lton E. L.WILLIAMSON EXECUTIVE VICE PRESIDENT THE LOUISIANA LAND AND ]~XPLORA~ION (~O~IPANY SUITE 12OO - 22S BARONNESTREET P. O. BOX 60350 ~]~w ORX~AN~ IO160 November 24, 1969 HLB TR,~ ~ KLV ~ . .... R~!. FILE Mr. Thomas R. Marshall, Jr. Executive Secretary Alaska 0il and Gas Conservation Committee 3001 Porcupine Drive Anchorage, Alaska 99501 Gentlemen: 7 The Louisiana. Land and Exploration Company, an owner of substantial leasehold interests on the North Slope and within the area affected by the proposed Prudhoe Bay Field Special Rules, would like the following statement put into the record of the subject hearing: The Louisiana Land and Exploration Company is basically in accord with the Special Field Rules being sought by Atlantic Richfield Company and BP 0il Corporation, with the exception of Rules 7 and 8. Sufficient data upon which to base permanent rules are not available at this early stage of development. We, therefore, share the opinion of Hunt 0il Company and Amerada Hess Corporation that these rules be temporary in nature and suggest a period of 18 months. Regarding Rule 7, we feel that bottom hole pressure surveys should be run prior to production and annually thereafter in all wells until such time as the reservoir performance lends itself to the "key well" method of monitoring. We submit, regarding Rule 8, that G0R tests be run semi- annually and the results of such tests be filed with the Committee. These tests may be witnessed, if an operator so desires. Alternately, establishment of rules similar to Rules 7 and 8 could well be deferred until a later hearing. The disposition of gas, both solution and gas cap gas, is unresolved. This matter, which is of prime concern to operators and the State, should, in our opinion, be clarified with special rules prior to placing the field on production. Mr. Thomas R. Marshall, Jr. Page 2 November 24, 1969 Our Company has long maintained a policy favoring uniti- zation based on fair and equitable terms. We reaffirm this position regarding our activity in the State of Alaska in general, and the Prudhoe Bay Field in particular. We welcome the opportunity to work with other operators and the State of Alaska toward that end. Yours very truly, THE LOUISIANA LAND AND EXPLO~TI ON~0MP.ANY Executive Vice President DES: csc STATE OF ALASKA DEPARTMENT OF NATURAL RESOURCES DIVISION OF OIL AND GAS Alaska Oil and Gas Conservation Co_mmittee Conservation File ,~83 Motion of the Alaska Oil and Gas Conservation Committee to hold a public hearing to hear testimony to determine the proper pool rules for the Prudhoe Bay Field PROTEST AND DE~j~ND FOR HEARING its ~ ~ T Comes now PAN ~.i~-~CAN PETROLEUM CORPORATION, and enters iappearance as an interested party in the hearing held November 13, 1969, on the above matter. I · RALPH G. CREWS ATTORNEY AT LAW FIRST NATIONAL BUILDING 425 "G" gTREET ANCHORAG£, ALASKA 99~01 Pan American Petroleum Corporation protests generally the adoption by the Oil and Gas Conservation Committee, for the Prudhoe Bay Field, or any portion thereof, of any rule pertaining to Items 1, 2, and 3, listed in the Notice of Hearing published in this mat- ter on October 7, 1969, and protests specifically the adoption of rules 1, 2, and 11 pertaining to said three items proposed in this hearing by Atlantic Richfield Company on behalf of itself and all other parties who concurred in said proposal, and requests that a hearing be held in accordance with the requirements of the Alaska Ad inistrative Procedure Act and Alaska Statute 31.05.100 before any action is taken to adopt any such rule. In support of its general and specific protest and demand for a hearing, Pan American Petroleum Corporation shows as follows: 1. No proposal for any field rules pertaining to any of the three items hereinabove first set out has been made in this matter prior to the hearing held November 13 and 14, 1969, by the Oil and Gas Conservation Committee or by any interest party. The protest and request for a hearing filed herein on behalf of Pan American Petroleum Corporation as a part of the record of the hearing must be considered as hav- ing been filed simultaneously with the presentation of the proposal for said field rules submitted by Atlantic Richfield Company, on behalf of itself and the other parties who have concurred in their recommendation. 2. Pan American Petroleum Corporation, a Delaware corpor- ation, is duly authorized to do business in the State of Alaska, and owns an interest in oil and gas leases issued by the State of Alaska covering 66,074 acres within the Prudhoe Bay Area. It holds an interest in leases within, or immediately adjacent to, the proposed pool limits of each pool for which field rules are proposed. Said leases were acquired by it from the State of Alaska for a consideration of $97,216,615.00 which consideration has been paid in full and which sum represents almost ten percent of the approxi- mately $900,000, 000.00 realized by the State of Alaska for the sale of oil and gas leases within the Prudhoe Bay Area at the sale held SePter~er 10, 1969. 3. The right to conduct oil and gas exploration, develop- ment and producing operations on the lands covered by said leases in accordance with the rules and regulations in effect at the time its interest in said leases was acquired, by it is a valuable property right and one which cannot be taken o FFIC~E-~ OF RALPH G, CREWS ATTORNEY AT LAW FIRST NATIONAL BUILDING 421~ "G °' STREET ANCHORAGE, ALASKA 99BO! away, dzmln~she, or restricted without due process law. 4. The adoption of the rules recommended in this hearing by Atlantic RiChfield Company and others would adversely affect this protestant, and will result in waste of oil and gas, will impair the correlative rights of this protestant, and will result in a reduced recovery of oil and gas from the leases issued by the State of Alaska, thUs destroying or substantially reducing their value. 5. The testimony does not show that waste of oil or gas will result, or that the correlative rights of the proponents of said rules will be impaired, or that unnecessary wells will be drilled by said proponents if the rules they propose are not adopted. On the contrary, the testimony shows that the proponents may, under the existing rules establishing drilling units and a spacing pattern, conduct operations upon their own acreage in accordance with the well density and spacing pat- tern they propose. 6. In support of the proposed Rule No. 1, and the various exhibits specifying the horizontal limits of each pool, for the proposed Prudhoe Bay Sand Pool, Prudhoe Bay Lisburne Pool, and Prudhoe Bay Kuparuk River Pool, the Atlantic Richfield Company and the other proponents of the proposed pool rules propose vast horizontal pool limits and a vertical definition for each pool based upon that portion of the log of only a single well which has _penetrated the pool. Even the portion of the logs which were presented lack proper identification as to the type of log, and show no horizontal scale. Many other well logs are available to the proponents which would tend to either prove, or disprove the reasonableness of the pro- posed pool limits. In the case of the Kuparuk River Pool the log of another well was produced by Standard Oil Company of California, a protestant. If this log proved nothing else, it demonstrated that all available logs of all wells within the proposed pool limits should be considered before an attemp' is made to define either the horizontal or the vertical limits of pool. 7. The only proposed pool as to which competent evidence has been introduced as to the proper well spacing pattern to be followed in the development of the pool is the Kuparuk River Pool. As to this pool the evidence produced by Standard Oil Company of California established beyond any doubt that no change in the drilling units and spacing pattern now in effect should be made at this time. As to the proposed Prudhoe Bay Sand Pool and the pro- _ posed Prudhoe Bay Lisburne Po°l no competent evidence has been produced showing any need for a change in the drilling units and spacing pattern now in effect. Protestant herein has no knowledge of any such evidence, and therefore alleges that if all of the competent evidence available to Atlantic Richfield Company and the other parties proposing a change in the drilling units and spacing pattern now in effect were pro- duced, this evidence would show that no such change should be made at this time. Proposed Rule 11 would establish 640 acre spacing for any additional pools which may be discovered in the Prudhoe Bay Field. Pan American concurs in the objection to this rule made by Standard Oil Company of California. There is no evidence to support such a rule. Its adoption would be contrary to the statute authorizing the establishment of drilling units and spacing patterns. -2- OFFICE~ OF ~:~ALPH (~o CREWS ATTORNEY AT I-AW FIRST NATIONAL BUILDING 425 "G" STREET A~C HORAGE, A~SKA 9950 ! 8. Where opinion evidence is offered in support of a request for the adoption of a special field rule the basic data or facts upon which such opinion is based must be pro- duced. If they are not produced no proper foundation has been laid for the opinion evidence. The evidence is thus incompetent, hearsay, and inadmissible and will not support an order establishing field rules in the face of a protest to ' the adoption of such a rule. 9. A statement that the log of a well shows that the well did or did not encounter a certain formation or pool, as to the depth at which it encountered any poo!, or as to any other information shown on the log is incompetent and inadmissible unless the log upon which the statement is based is also pro- duced as evidence. The log itself is the best evidence. 10. In any case in which a protest to the issuance of a proposed field rule or rules has been filed the party or par- ties proposing said rule must produce all of the basic data or information required to be filed by it or them with the Depart- ment of Natural Resources which might tend to show the need or lack of need for the field rule proposed. The basic data which Pan American Petroleum Corporation contends must be produced by a proponent of a field rule is limited to that basic data which is required to be filed with the Department of Natural Resour- ces of the State of Alaska as a public record, and which may be kept confidential for a period of two years after the time it was required to be filed if the owner so requests. It is the position of protestant that when the proponents request the Committee to take action on any matter as to which said basic data is pertinent evidence, such request for aCtion constitutes a waiver of the confidential status of any such basic infor~ mation which may properly be considered by the Committee in determining whether it should take action in accordance with the proponents' request. 11. This protestant does not by its demand for the produc- tion of evidence seek to require the production of any infor- mation other than the basic well data required to be filed with the Department of Natural Resources of the State of Alask~ Protestant does not seek the production of this data if the request for the adoption of proposed rules 1, 2, and 11, per- taining to items 1, 2, and 3 in the Notice of Hearing is withdrawn by the proponents thereof and the Committee takes no action to change the existing rules. Since the hearing was called by the Committee on its own motion~ the proponents should be permitted to withdraw their proposalsr if they do not wish to disclose the necessary data. Pan American agrees with Atlantic Richfield Company and t~ other proponents that data not required to be furnished to the State, interpretive material, professional work product and ot~ similar material is proprietary information and that the owner thereof may keep it confidential indefinitely. This protestan~ does contend, however, that if pertinent proprietary informati¢ in the possession of a party is not produced, the failure to pa duce such evidence may in some cases result in a failure of pre which would justify a denial of the action requested by such party. This protestant contends that the cross examination conduc- ted by the Committee at the hearing in an attempt to secure the disclosure of additZonal data established beyond any doubt that the proponents have failed to meet the burden of proof as to their proposed rules 1, 2~ and 11. -3- er n OFFICES OF RALPH (~, CREWS ATTORNEY AT LAW FIRST NATIONAL BUILDING 425 "G" STREET ANCHORAGE, ALASKA 9950! II. Pan American Petroleum Corporation concurs in the recommendatio Df Atlantic Richfield Company and others as to proposed rules 3, 4, 5, 6, 7, 8, 9~ and 10. The Committee should recognize, however, tha such rules should be considered as temporary and subject to change ~s additional information becomes available. III. Pan American Petroleum Corporation recognizes that no action on Items 8 and 9 in the Notice of Hearing is recommended by any interes ted party or by the Committee itself at this time. They do wish to comment upon both items. 1. With reference to the plans for disposition of pro- duced gas, it agrees that it is impossible to state at this time how the problem of disposition of produced gas and the related problem of disposition of gas from wells capable of producing gas only should be handled. ~natever plan is fol- lowed should afford each owner in the field or pools a reason- able opportunity to produce its just and equitable share of the oil and gas in the pool. This can best be accomplished through unitization of each pool. 2. Pan American PetroleUm Corporation agrees with the statement of Standard Oil Company of California that all pro- ductive pools in the Prudhoe Bay Field should be unitized. From the testimony presented at the hearing in this mat- ter it appears that only unitization of the Prudhoe Bay Sand Pool is being discussed at the present time, and that those parties who are participating in the unit negotiations have agreed among themselves that they will exchange information on wells drilled in the proposed unit area and withhold in- formation from parties not invited to participate in the unit negotiations, even though non-participating parties now hold leases which may ultimately be proved to be productive of oil or gas from the same pool. Pan American Petroleum Corporation has not bee invited to participate in the unit negotiations now being conducted and has been advised that it will not be invited to partici- pate. It does not desire to participate in unit negotiations unless all interested parties are allowed to participate. Unit negotiations conducted on the present basis do not seem calculated to achieve early and complete unitization or to achieve unitization which will afford the State of Alaska and each owner of productive lands within a pool an oppor- tunity to produce or receive its just and equitable share of the oil and gas produced from all of the pools. Unless Pan American Petroleum Corporation is satisfied that any proposed unit agreement does allow each owner the opportunity to pro- duce or receive its just and equitable share of the oil and gas in each pool, and in all pools, it will not voluntarily execute such a unit agreement, will resist the involuntary inclusion of any leases in which it holds an interest in such a unit, and will object to the approval of any such unit agree- ment by the State of Alaska. OFFICE5 OF RALPH (~. CREWS ATTORNEY AT LAW FIRST NATIONAL BUILDING 42S '° G" STREET ANCHORAGE, ALASKA 9950 ! DATED at AnchOrage, Alaska, this 28th day of November, 1969. Respectfully submitted, PAN AMERICAN PETROLEUM CORPORATION Anchorage, Alaska Oscar E. Swan Security Life Building Denver, Colorado -5- DELANEY, WILES, MOORE, HAYES & REITMAN, INC. ATTORNEYS AT LAW 36O K STREET ANCHORAGE, ALASKA November 24, 1969 Re: November 13 and 14, 1969 Conservation Hearings Designated Conservation File A-3 Alaska Oil and Gas Conservation Committee Attention: Mr. Homer Burrell, Chairman Gentlemen: This is to summarize and supplement Standard Oil Company of California's request that the present State-wide 160-acre spacing will remain in effect for the Kuparuk River Pool being defined in the North Kuparuk State No. 1 Well between the depths of 6765 to 7765 feet and in the Kavearak Point Well #32-25 and interval between the depths of 6900 and 7710 feet and any other pool, excepting the Prudhoe Bay Sand Pool and the Prudhoe Bay Lisburne Pool. Alaska Statute, Section 31.05.030, Powers and Duties of department, provides in pertinent part as follows: "(e) The department may regulate, for conservation purposes (3) the spacing of wells;" Alaska Statue, Section 31.05.100, Establishment of drilling units for pools, provides in pertinent part as follows: "(a) For the prevention of waste, to protect and enforce the correlative rights of lessees in a pool, and to avoid the augmenting and accumulation of risks arising from the drilling of an excessive number of wells, or the reduced rec_overy which might result from too small a number of wells, the department shall, after a hearing, establish a drilling unit or units for each pool. The establishment II of a unit for gas shall be limited to the production of gas. (Emphasis supplied). Pursuant to the above sections of law, the State has promulgated Conservation Regulation 2061, Well Spacing. The pertinent portion of this regulation is set forth below: "(b) Where oil has been discovered, not more than one well shall be DELANEY, WILES, MOORE. HAYES & REITMAN. INC. ATTORNEYS AT LAW 360 K S'I'REET ANCHORAGE, ALASKA Alaska Oil and Gas Conservation Committee Attention: Mr. Homer Burrell, Chairman -2- November 24, 1969 drilled to that pool on any governmental quarter section or governmen- tal lot corresponding thereto, nor shall any well be drilled to that pool on a governmental quarter section or governmental lot correspond- ing thereto which contains less than 150 acres, nor shall the bottom hole location or pay opened to the well bore be nearer than 500 feet to any property line nor nearer than 1,000 feet to any well drilling to or capable of producing from the same pool." As can be ascertained from the law and regulation, the uniform spacing adopted by the State is no more than a governmental quarter section. The law and the regulation also provides that if there is to be an exception to this spacing the party requesting exception must produce sufficient evidence to justify in the minds of the Committee that a change is in the best interests of the State. The statute and regulations also place the burden of proof to establish these facts on the one requesting the exception. A review of the transcript of the hearings fails to reveal any evidence which would justify a spacing exception to rule 2061 with respect to the Kavearak River Pool. In fact, the transcript is replete with testimony to the effect that the parties requesting the exception had no information or data to justify such an exception with respect to the above-mentioned pool. On the other hand, Standard Oil Company of California presented evidence which strongly suggests the existence of lenticular sands within the Kuparuk River Pool. As under- scored in the statute set forth above, with a condition of lenticular sands too wide a well spacing, in all probability, will result in reduced recovery of hydrocarbons in violation of the statute. Standard further presented testimony, well logs and production tests that strongly suggest that the productivity from the Kuparuk River Pool per well will range from 500 to 1,000 barrels per day. Standard further pointed out that with such an individual well productivity, one well per 640 acres will take an inordinate length of time to produce the recoverable oil under any reasonable production schedule. On the other hand, four wells per 640-acre tract or a well spacing of 160 acres should result in producing the recoverable oil in a reasonable field life and achieve the optimum ultimate recovery which is beneficial to both the State and the operating company. It is conceivable that as additional data is developed from further drilling, that even a closer well spacing may be required for the maximum ultimate recovery. This should result in maximizing benefits to the State of Alaska as well as to the operating company. Standard would further like to point out that the bonus bid for tracts beneath which the Kuparuk River Pool is pres mt, were based upon Conservation Regulation No. 2061 which provides for the standard quarter section of no more than one well per governmental quarter section. To change this regulation with no evidence to justify such change, would result in an undue hardship to Standard. DELANEY, WILES, MOORE, HAYES & REITMAN, INC, ATTORNEYS AT LAW 360 K STREET ANCHORAGE. ALASKA 'r=, =DunNr ~)79.358 Alaska Oil and Gas Conservation Committee Attention: Mr. Homer Burrell, Chairman -3- November 24, 1969 In summary, it is Standard's request that the Committee retain the one- quarter governmental spacing as provided by Regulation 2061 as to the Kuparuk River Pool and all other pools other than the Prudhoe Bay Sand Pool and the Prudhoe Bay Lisburne Pool. Standard feels that this may be done by the Committee affirmatively finding that there was no evidence presented to justify an exception to the quarter section spacing by any of the proponents at the hearin§. The Committee could also affirmatively find that in view of the testimony presented by Standard at the present time the 160-acre spacing is prudent for the Kuparuk River Pool. Such affirmative findings by the Conservation Committee will provide Standard with the necessary assurance to commit funds for early design of drilling and production islands and the commitment of funds to develop such pool. Re~spectfully submitted, E. '~. W~ies, E~q. Dela~y~ Wiles, Moore, Hayes & Reitman, Inc. HOUSTON, TEXAS 77001 PRODUCTION DEPARTMENT CONSERVATION & REGULATION S. F. HOLMESLY COORDINATOR November 24, 1969 POST OFFICE BOX 21EIO Mr. Homer L. Burrell, Director Division of Oil and Gas 3001 Porcupine Drive Anchorage, Alaska 99504 Dear Mr. Burrell' I wish to £ile the attached Closing Statement in regard to the promulgation of field rules for the Prudhoe Bay Field on the behalf of Humble Oil & Refining Company. Yours very truly, SFH'vah Attachment cc' Mr. Ralph F. Cox Mr. John Martyr Mr. John Saint HUMBLE CLOSING STATEMENT PRUDHOE BAY FIELD RULES HEARING Sec. 31 05 100 of the Alaska Statute Title 31 gives the Committee two charges for the establishment of drilling units for pools. 1. To avoid .... the drilling of unnecessary wells. 2. To avoid .... the reduced recovery which might result from too small a number of wells. The Statute gives equal weight to these charges, both of which are found in the same paragraph. Based upon the testimony at the hearing on November 13 and 14, the Committee is advised of the lack of data on which to base a spacing rule as prescribed by the Statute for each of the pools. But, the Committee has received substantial evidence sup- porting a well density rule for the pools which is needed during the period of field development with no production. The Committee has statutory authority to promulgate such a rule under the powers and duties set forth in Sec. 31 05 30. The rules proposed by Atlantic Richfield, British Petroleum, and Humble will prevent waste during the period of development when no significant pro- duction occurs and will in time afford the data on which to base a permanent well spacing rule under the provisions of Sec. 31 05 100. The Committee is also concerned with designating an area to which the rules may apply during development. It is not required by statute that this be done; and if not done, regulations will apply to the pool with undefined limits. The adoption of a - 2 - rule which designates an area avoids the confusion that might occur during the development period and avoids the problem of operators developing on different well spacing patterns in a pool. It is for this same reason that a designated area for rule application should be amply large to cover the probable produc- tive area of a pool during the development period. Once the pool is developed, the area designated as subject to rules may be conformed to the productive area limits. Humble concurs with Atlantic Richfield and British Petroleum rule recommendations and urges their adoption. The ef£ect of the testimony at the hearing was that temporary rules be adopted. Humble opposes the recommendations of Standard of California for the Kuparuk River Sand Pool. We believe Standard of California's testimony was inconclusive on the subject of Kuparuk River Sand Pool's well spacing and gave insufficient information to make a reasonable judgment as to the optimum spacing for the pool. Standard o£ California's recommendations were limited to the Kuparuk River Sand Pool and were not joined in by other operators, all of whom recommended 640-acre well density for all pools. Humble Oil & Refining Company Houston, Texas GERALD GAN OPOLE CONSULTanT-CERTIFieD PrOFESSIONaL GEOLOGIST 506 6TH AVE., Suite 6 ANChORaGE. ALAE~KA 99501 277-0124 November 20, 1969 Mr. Homer L. Burrell, Director Division of Oil and Gas 3001 Porcupine Drive Anchorage, Alaska 99504 Gentlemen: Re: i ,c, i_, Co, Statement for Addition to Conservation Committee Hearing Prudhoe Bay Field Rules I attended the Prudhoe Bay Field Operations Hearings held in Anchorage on November 13 and 14, 1969 and was once again very impressed with the fact that the Alaska Oil and Gas Conservation Committee is required to formulate producing and conservation regulations on the basis of information volunteered by the very companies being regulated. At this stage of development in the Prudhoe Bay Field, there is one problem of control that is so important that it virtually nullifies all the other items that were discussed at very great length by the operat'ors. The problem of beneficial use of the gas, which the testifying company experts refused to comment on, 'is of such paramount importance that the Conservation Committee would be derelict in their duties to allow any production without having first established complete gas utilization regulations. An example of the extremely deleterious effect to the State of oil production without, gas control may be viewed in the offshore Cook Inlet oil fields. Here, for lack of complete information, the State allowed giant oil fields to develop without gas control. There are now 13 m~lti-well offshore platforms producing a total of nearly 200,000 barrels of oil per day and the oil reservoirs are being rapidly depleted by flaring and completely wasting the associated gas at the rate of many millions of cubic feet per day. At the onset of offshore production, it was apparent that the mechanics of the producing zones were similar to those of the adjacent onshore SwanSon River Oil Field. At Swanson River, the pressure maintenance program of reinjecting gas to the producing formations has been very successful in maintaining production and wlll,~;~i~~n the ~LVI~.tON OF Oit AND OAS Statement on Prudhoe Bay Field Rules Page Two production of tremendous amounts of oil that would have been unrecover- able under pressure depletion production. The reinjected gas can also be produced and fully utilized any time in the future when it no longer supports oil production. For some unexplained reasons, the companies producing offshore fields did not choose to reinject formation gas and the State has further allowed the companies to flare all the gas without paying a cent in royalties or insisting on any beneficial gas use. The results of this are somewhat ludicrous in that offshore operating companies are now releasing information through trade and State sources, bemoaning the fact that offshore field pressures and associated producing rates and reserves are falling off so much faster than they anticipated that they might not recover their investments in some cases. As declining pressures and producing rates can be factually established, the State is requested by the companies to take it easy and not burden them with additional restrictive practices such as beneficial gas use that might add to their present marginal producing operations. In the Cook Inlet, millions of barrels of oil and billions of cubic feet of gas will be completely lost and wasted for lack of beneficial gas use regulation by the State. Because of the fantastic reservoir potential of the Prudhoe Bay Field, the waste of our irreplaceable natural fuel resources could be infinitely worse. Take the hypothetical example of an operator in the Prudhoe Bay Field that holds a lease overlying a gas cap in one of the pools. As there is no foreseeable market for North Slope gas, the operator would be inclined to blow off the gas as quickly as the oil surging in Could be produced. Although this would result in a great deal of oil for the operator, loss of pressure in the entire pool could result in an unrecoverable loss of billions of barrels~of oil. Surrounding lease operators would be left with lots of oil in the ground, but no formation pressures to recover the oil. To alleviate this possibility, field producing units are some- times formed by the operators with the gas cap owners in the bargaining driver's seat. Theoretically, field operators could be forced into unitization by the State although the paucity of volunteered essential engineering data would severely handicap the State's determination of proper production practices and allocations° Unitization agreements alone, however, do not insure production practices that are necessarily beneficial to anybody but the companies concerned. Companies are obligated to pay out their very large investments as quickly as possible...and their large investments Statement on Prudhoe Bay Field Rules Page Three are necessitated by the very high competitive lease costs and by the high costs of development and operating in Alaska, especially on the North Slope. Apparently the State is obligated to decide on production practices only on the basis of information presented at the hearing. If the State does not exercise its authority to insist on proper pressure maintanence and complete gas utilization, other items of contention which included well spacing, permafrost production methods and bottomhole pressure testing are moot. As a professional member of the oil industry, and, more important, as an Alaskan, I request the Division of Oil and Gas withhold approval of production until the State has accumulated complete well .data to insure a determination of optimum production practices...a determination completely independent of volunteered oil company in fo rmat ion. Re~ submitted, Gerald Gano ~~o~~ Qualifications: Certified Professional Geologist By the American Institute of Professional Geologists Certified Petroleum Geologist By the American Association of Petroleum Geologists Registered Geologist and Petroleum Geologist By the State of California GG/sc :rete Research g Technol .y P. O. BOX 4-1875 - SNOW SHOE LANE ANCHORAGE. ALASKA 99503 PHONE 907-344-252T 25 YEARS OF EXPERIENCE IN RESEARCH, ~F ~q ~'¥L'~,'t~ ~'77ij~'~ DESIGN. MANU FACTU RE, PLACING, AND CONTROL OF THE FOLLOWING CONCRETES: AGRESSiON RESISTING. AIRENTRAINED, ALU MINATE CEMENT. ANHYDRITE, ARCH ITECTU RAL. ARTISTIC. AUTOCLAVE, BASALT, BITUMINA. BOULDER. CANNERY. CHIMNEY, COLCRETE. COLD. ICE. CORK ELASTIC, DAM. DA I RY. DIFFUSION. DRAINAGE, DRIP, EXCELSIOR, EXPANDED SHALE, EXPANDED SLAG, EXPANDING, FILTER, FLY ASH, FOAM, FOUNDATION, GAS, GRANITE, GRINDSTONE, GROUTING, HIGHWAY, HIGH-TENSILE, HIGHEST TEMPERATURE, HYGROSCOPIC, I NSU LATI NG, KIESELGUR, LIGHTWEIGHT, LIMESTONE, LOW SHRINKAGE, MARBLE, MASS, MICRO. MOISTURE RESISTANT, MOISTURE RETAINING. NUCLEAR SHELTER, NYLON, OILRESISTANT, OCRATE, PERLITE, PIPELINE, POLISHED, POROUS, PUMICE, PUMPCRETE, PVA, QUARTZ, REINFORCED, REACTOR. RICE STRAW. SMELTER SLAG, SPUN, STEAMKILN, TAMPED. THERMIC WINTER, TUNNEL (FAST FLOW) TREMIE, VACUUM, VAULT, VIBRATED, VERMICULITE, WASHED SURFACE, WATER PRESSURE REST, WEAR RESISTANT, WOODSHAVING, YTONG, ZERO DEGREE TEMP., AND MANY MORE. SPECIALISTS FOR: TROUBLE SHOOTING PRODUCT IMPROVEMENT SPECIFICATIONS INVESTIGATIONS CUSTOM DESIGN Homer Burrell, Chairman, Oil & Gas Conservation Committee. VICTOR REVENTLOW CONSULTING TECHNOLOGIST RICHARD KENTOPP RESEARCH MANAGER :Dear Mt. Chairman; we wish to submit the following suggestion as part of the rules for developing oilfields in the Arctic: "In order to protect a wellhead against collapsing thru thawing action around the casing underneath the wellhead an area of at least 50 x 50 feet,centering the wellhead,shall be excavated 6 feet deep,and shall be filled with a loadbearing lightweight concrete as support for wellhead and casing. This concrete shall be of such a design as to provide a minimum buoyancy of 200 to .in order to support the wellhead even when the melting cone becomes larger than the covering 50' x 50' lightweight concrete slab." A lightweight concrete of about 30 lb/cuft will have this minimum buoyancy and will hold the casing rigid by levitation even when permafrozen ground turns into a waterpool thru sedimentation. A concrete which has these and other desirable qualities for use in the Arctic is described in en- closed paper. Sin ere yours .' crete Research Techn°i 25 YEARS OF EXPERIENCE IN RESEARCH. DESIGN, M A N U F A C T U r E, PLACING, AND CONTROL OF THE FOLLOWING CONCRETES: AGRESSION RESISTING, AIRENTRAINED. ALUMINATE CEMENT. ANHYDRITE, ARCH ITECTU RA L, ARTISTIC, AUTOCLAVE. bA SA LT, BITUMINA, BOULDER. CANNERY, CHIMNEY. COLCRETE. COLD. ICE. CORK ELASTIC. DAM. DAIRY, DIFFUSION. DRAINAGE, DRIP, EXCELSIOR, EXPANDED SHALE, EXPANDED SLAG, EXPANDING, f I LTeR, FLY ASH. FOAM. FOUNDATION. GAS, GRANITE. GRINDSTONE. GROUTING. HIGHWAY. HIGH-TENSILE, P. O. BOX 4-t875 - SNOW SHOE LANE ANCHORAge, ALASKA 99503 PHONE g07-344-2827 USE OF EXPANDED POLYSTYRENE BEADS AGGREGATE IN LIGHTWEIGHT CONCP~ETE FOR ROAD, RAILROAD AND GENERAL CONSTRUCTION IN ALASKA VICTOR REVeNTLOW CONSULTIN(~ TECHNOLOG 1ST RICHARD KENTOPP RESEARCH MANAOER SUP~4ARY This paper describes the manufacture of low-density concrete out of Portland Cement and expanded polystyrene beads, its properties, and its affinity to Arctic Construction of roads, railroads, airports, oil rig pads, buildings, etc. Lightweight concrete made from such expanded beads has proven SPECIALISTS FOR: TROUBLE SHOOTING PRODUCT IMPROVEMENT SPECIFICATIONS INVESTIGATIONIB CUSTOM DESIGN HIGHEST TEMPERATURes) HYGROSCOPIC. have sufficient strength for load-bearing units, as well as giving INSULATING. KIESELGUR, LIGHTWEIGHT. outstanding thIer~al insulstion. LIMESTONE. LOW SHRINKAGE. MARBLE. The regular spherical form of expanded 'polystyrene beads MASS, MICRO, MOISTURE RESiSTANT~Ontributes to the formation of a cell strncture in the concrete that MOISTURE RETAINING. NUCLEAR SHELTER. NYLON, O ILRESlI~TANT. OCRATE. PERLITE. PIPELINE. POLISHED. POROUS. PUMICE, PUMPCRETE, PVA. QUARTZ. REINFORCED. REACTOR. RICE STRAW. SMELTER SLAG. SPUN. STEAMKILN, TAMPED. THERMICWINTER, concrete. Certain recommendations are made. TUNNEL (FAST FLOW) TREMIE, VACUUM. GENERAL AS?ECTSI VA U LT. VIBRATED, VERMICULITE, Lightweight concretes are well known throughout the industry. WASHED SUmF^CE. WEAR R~SiSTANT. Depending on the manner t~he lightweight is achieved, we can classify WOODSHAVING. YTONG, ZERO DEGREE TEMP., these concretes by the manufacturing methods. AND MANY HOME. lends the concrete comparatively high compressive strength. Precast lightweight units, as well as in-place concrete can be made to any required density and with consistent mechanical properties. Polystyrene can be expanded up to fifty times its original size on the site, thus reducing transportation problems to a minimum. C°n- ventional equipment is used for preparing, handling and placing this -2- (a) Lightweight concrete with artificial air enclosures (voids) generated by use of foam, foaming agents, or gasses. (b) Lightweight concrete manufactured by using lightweight aggregates, usually porous aggregates, such as pumice, expanded shale, cinders, etc. (c) Lightweight concrete manufactured by using heavyweight aggregate of equal grain sizes, thus allowing voids to develop, between particles, which reduce the weight. Important for our purpose is the fact that only the lightweight concretes mentioned under (b)'and (c) can readily be produced on the site, while foam con- crete and .products made of foam concrete require a stationary plant in order to insure ~niform results. Lightweight concrete, in normal use, should have good insulating abili- ties, as well as the necessary strength, both of which depend' On the density of the concrete. Most lightweight concretes used by the .building ~ndustry today weigh from 90 to 110 lbs. per cubic foot, with exceptions going down to 50 lbs. (foam , concrete). All these concretes have a certain, coordinated insulatJ, ng value. 'However, conductivity at these densities is still too high for our considera- tion. A lightweight concrete for our purpose, as constructive road-building material, with optimum thermal properties, should have the following character- istics in order to be of use in the Arctic. (a) Low density (b) Sufficient strength .and flexibility (c) UnifOrm low thermal conductivity (d) .Low absorption (e) Minimum weight or~ bulk of raw material for transportation. . , .. -3- (f) Ease of manufacturing at any site and temperature ~(g) Good workability and placeability, with conventional equipment (h) Good setting amd hardening properties even at temperatures below freezin~ Author of this paper conducted many field and laboratory tests of con- cretes with the above properties in the middle Fifties in Vancouver, B.C., in his own plant, "Dura Bloc Mfg., Ltd. using wood chips, perlite, vermiculite and expanded polystyrene beads. However, since climatic conditions did not require such severe thermal properties, these tests were abandoned after erection of about thirty 1 and 2 story buildings out of "wood-chip concrete." Lately new test series were made in West Germany with lightweight concretes also having a density of less than 50 lbs. per cubic foot, using expanded polystyrene beads. The results of these tests, and some of the possibilities of their application in the Arctic, shall be reported in this paper. Lightweight concrete made with expanded polystyrene beads, shall be subsequently called "STYROPOR."* CHARACTERISTICS OF STYROPOR Styropor differs from all other lightweight concretes due to the ~ha=acteris~ics of the expanded beads which are used as aggregates. (a) Extremely low loose we lght of.expanded particles (3/4 to 1 1/4 lbs. per cubic foot). (b) Excellent thermal resistence of the porous particles. (c) No particle absorption on account of their closed cellular structure. (d) High static strength of particles because of their spherical shape, giving the concrete a strong skeleton. The pre-expanded styrene beads might be compared to an excessive air entraining agent and act at the same time as liner and filler for the cells the agent gen-. erates. In other words: "packaged air" is built into the concrete. Registered by BASF' Corporation. By exactly measuring the quantity of beads for every cubic yard of concrete, a ligt~tweight concrete of pre-designed cellular structure can be produced, i.e., weights and thermal properties of Styropor can be controlled and uniformly reproduced. POLYSTYRENE B~DS AS AGGREGATES Polystyrene beads are a polystyrene-based product containing an inte- grated volatile hydro-carbon expanding agent. In steam the polystyrene softens, thus giving the expanding agent a chance to blow up the particle. This process is call'ed prefoaming, and is a controlled partial or complete expansion of the expandable polystyrene beads. Equipment for continuously prefoaming operates as follows: A steam aspirator injects the beads into the prefoamer, and an agitator prevents them from fusing together as they are forced to the top of the drum and out the discharge chute. The density is controlled by ~adjusting the feed opening into the aspirator, height of the discharge chute, the steam pressure, or the amount of air. Expansion is possible up to 40 to 50 times the original size. After the beads are expanded and discharged, the expanding agent slowly diffuses from tile beads into the atmosp[~ere. A twe~ty-lour hour storing period is suf- ficient to let the excess gas escape from the expanded particles. During this time air replaces the gas in the cells of the beads. By selecting tile proper grade of raw expandable polystyrene and by timing the prefoaming process correctly, bead sizes can be pre-determined. They must 'be kept as small as possible (passing No. 12 Tyler, retained on No. 16), since strength of Styropor at any given density will be higher the finer the cellular structure. Unit weight of the beads has no influence on the strength of the concrete; however, for thermal and economic reasons the weight should be kept as low as feasible. MANUFACTURE OF STYROPOR Only Styropor ~ith unit weights from 20 to 50 lbs. per cubic foot i$ discussed at this time. European test series have indicated that about 37 lbs. per cubic foot signify a crucial point in the manufacture of Styropor. In concretes weighing more than 37 lbs., all voids between the particles are filled up with cement-paste. In Styropor with weights below 37 lbs. per cubic foot the cement-water-paste will not fill the voids between the beads, thus adding to the insulating factor. However, the lower weight concrete has still relatively high strength due ~o the arch effect of the reinforced wailm of the beads, which brace each other in the concrete skeleton. The reinforcement of the beads is achieved by a patented precoating proce~m$ which not only increases compressive strength, but also accelerates ~he setting time. Thermal and strength proPerties of Styropor are governed by (a) the manufacturing methods; (b) the unit weight; (c) grain size of the beads; (d) the type of cement and (e) additions of fine sand, whenever these are used. A pourable Styropor can be produced in the ~'ollowing way: Expanded polystyrene beads are filled into a turbine-type mixer and mixed with water plus an organic binder. As soon as the mix starts to become m~icky, pre-mixed water-cement-paste is added which will coat the particles. Thereafter, the remaining cement, water, and if desired., fine sand Can be added to conclude the mixing process, or if desired the coated beads can be dried, then drybatched with cement and containerized for later use. During the mixing process cement must be uniformly disbursed in order to provide maximum strength. This requires usually finely ground cements, like -6- high early cement, which might be pre-mixed into a colloidal water-cement paste, preferably in high speed mixers and then added to the precoated styrene aggregate. In mixes of concretes with less weight than 37 lbs. per cubic foot, sand additions become useless since they only increase the weight without increasing the strength. They might even decrease the strength unless the sand is of flour fine- ness. Coarser sands will remove the precoating from the beads during the mixing operation, if mixed in a one-cycle operation. The water-cement factor is of the same importance as in any moisture on account of their closed cellular structure. Therefore, onlY enough water has to be added to make the mix plastic and, of course, for the hydration of the cement paste. In general, a water-cement ratio of .4 will result in a mix of plastic consistency at unit weights from 30 to 40 lb/cu, ft. In placing Styropor, no compacting, vibrating, tamping or other den- $ifying methods are necessary. The density obtained in mixing is about equal to the desired density of the concrete in place. Another characteristic of this concrete is the low heat loss during hydra- tion. Expanded styrene beads haVe so little body that they take up very little heat. More heat remains available than in other lightweight aggregates for the hydration process, thus speeding it up. The low thermal conductivity of the particles prevents heat loss to the outside. This makes Styropor ideal for placing during freezing temperatures, on or in permafrost. Styropor can be mixed, placed and cured at temperatures as low as minus 10 degrees F. without any protection or heating, other than chemical protection. Initial setting of the cement is unchanged while strength development becomes insignificantly slower than under normal curing temperatures. -7- MIX CALCULATIONS The final density of Styropor is essentially governed by the amount of cement, water and sand. At a unit weight of 31 lbs. per cubic foot for example, the portion of styrene beads will be about 2 - 1/2% of the total weight, but it will also be 75% by volume. From a practical point of view it is therefore better to measure this type of aggregate by volume than by weight; while amounts of cement, water and sand will have to be added by weight. One cubic yard of loosely poured expanded styrene beads is always used as basis for a mix design. Cement, water and sand can be calculated to the exact unit weight of the final concrete, which in turn governs strengt~ and K-Factor. (a) Compressive strength and flex strength Compressive strength of every concrete depends primarily on its density, i.e., on the quantity and proportions of .aggregate and hardened cement paste. Picture 1 shows test results on compressive strength of S'tyropor in relation to its density, as reported by Hohwiller and Koehling. These tests were made in Germany using 20 x 20 x 20 cm cubes. Compared to compressive strength re- sults obtained with standard 12" cylinders, the sgrength reported is about 13% lower than cylinder breaks would have been. Picture 1. Variation of Compressive Strength With Density. (As reported in Betonsteinzeitumg, February, 1968) Flex strength in relation to density as shown in Picture 2 was also reported by above Civil Engineers, using a beam 4" x 6" x 28 1/2". The solid curve shows a Styropor with precoated beads; the interrupted curve, without precoating. Picture 2. Variation of'Flex Strength with Density. (As reported in Betonsteinzeitung, February, 1968) .t -9- (b) Modulus of elasticity The dynamic modulus of elasticity was reported by Hoh~iller and Koet~ling, as follows: For a unit weight of 28 lb/cu, ft. = 111000 psi For a unit weight of 37 lb/cu, ft. ~ 157000 psi For a unit weight of 46 lb/cu, ft. = 284000 psi For a unit weight of 50 lb/cu, ft. = 420000 psi (c) Shrinkage Ail lightweight concretes using porous aggregates have more shrinkage than standard concretes. Test results obtained so far on Styropor at unit weights from 19 to 43 lb/cu, ft. range from 0.01 to 0.02 per cent of the length of the tested specimen. Writer of this paper experienced the same amount of shrinkage in lightweight concrete out of mineralized woodchips. In practical use, however, no detrimental effects, were ~ found. A German test road section 230 feet long, 16 1/2 ft. wide With a 5" layer of Styropor as base and 3" asphalt topping showed no crack- lng. Further test series on this matter were still outstanding at the time of the German report, but should be available by now. (d) Thermal Expansion Thermal volume change was reported to be less than in standard concrete, mainly in the range from 70 degrees to 90 degrees F. (e) Thermal Insulation Styropor has very low conductivity compared with other lightweight concretes. The writer has at this time no final figures as to its con- ~Ructivity since this depends not~ only on the density of the material but -10- also on moisture content, the mean temperature, and temperature differ- ence. However, it can safely be assumed out of previous experiences wit!~ other iightweig~t aggregates and data submitted by the BASF Corp- oration (see picture 2A), that Styropor of 30 lb/cu, ft. will have a K-factor of about .5, which would let an 8" to 10" thick layer of Styropor have an overall heat transmission coefficient U of about 0.08 to 0.05 BTU. Test series on this matter are in progress in · Europe. (f) Moisture Moisture absorption is in all lightweight concretes of greatest impor- tamce on account of its influence on thermal Properties. Deciding for the absorption of Styropor is: (1) the structure of the aggregate 'skeleton in the concrete (Unit weights under 37 lb/cu, ft. have voids between the beads, while unit weights over 37 lb/cu, ft. have these voids filled with hardened cement paste. (Picture 3) Picture 3. Unit weight under 37 lb/cu, ft. Unit weight over 37 lb/cu, ft. -11- (2) the grain porosity, which is practically "nil" in Polystyrene beads. Test results on absorption, are reported as follows: (Specimen seven weeks in 65% relative humidity at 70 degrees F.) Unit weight Absorption by weight lb/cu, ft. % 19 7.3 34 2.1 40 3.5 Field tests which will show the influence of "'this absorption on thermal conductivity have been made in the meantime, but are not available to this writer at this time. Test results on adsorption (specimen completely submerged) have been reported as follow: Unit weight Adsorption lb/cu, ft. % by weight vol% 23 49.8 17.8 34 26.4 14.1 40 (g) Resistance to Frost Action 21.3 14.2' Freezing-thawing tests were carried out on "absorption" specimens. After 25 cycles compressive strength and flex strength were equal to those of specimens which were kept submerged in water. Freeze-thaw test on "ad- sorption'' specimen have not been reported; however, writer's experiemce in similar aggregates showed failure when specimens were frozen eom- pletely submerged in water. .... ,.~, .~.~,,,, ~, ~ -12- PRACTICAL APPLICATIONS During the years 1965 through 1968 many experimental applications of Styropor have been in progress. Results on most of these were not concluded in reports available to this writer at this time. Experimental erections of prefab- ricated buildings, floors and ceilings out of Styropor have led to mass produc- tion at least in Germany. Several road and railroad sections using Styropor as insulating as well as' load-bearing layers have-been built in Europe, while, as far as this writer knows, concurrent American installations have been confined to such mater-~ ials as Styrofoam. However, data available for the American installations have also established the fact that frost penetration on highways can be prevented by the use of styrofoam beneath the pavement. Successful experimental installations have been made by Dow Chemical jointly with Purdue University in Manitoba, Michigan, Minnesota and Iowa. It is the main objective of this paper to draw attention to the placing of Styropor directly on permafrost ground wherever climatic conditions demand this. Experimental European road sections have indicated that Styropor at den' sities from 25 to 35 lb/cu, ft. had sufficient load-bearing strength when placed on natural undisturbed soil (no indication as to the kind of soil). According to European reports, 2" of StyroPor were equivalent in strength to one inch of a standard load-bearing asphalt layer, i.e., with about 6 to 8 inches of Styropor on solid ground not only the whole sub-base and base of standard highway construc- tion could be eliminated, but also the thickness of the asphalt topping as load- bearing layer could be reduced. -13- Permafrozen ground is recognized in Alaska as excellent supporting base for road or railroad construction as long as it does not thaw out. The writer believes that an 8" layer of Styropor, protected against moisture, at a K-Factor of .5, will prevent th&~ ground from thawing. The advantages of placing Styropor directly on permafrost would be as follows: (1) Elimination of a 6 to 8 foot gravel bed which would be immensely costly in the Arctic and remains questionable as to its effect. (2) Permafrost ground in more or less level areas will not have to be ditched out; only tundra has to be removed. (3) Styropor can be placed with modified standard road-paving equipment, without damage to the land during the construction process itself, winter or summer. (4) Styropor Will fill in any unevenness of the stripped ground, thus elimi- nar'lng a gravel base, unless a constant film of water over the perma- frost during' summer construction demands a foot of gravel to keep the concrete above water level in placing. (5) Thickness of the asphaltic topping can be kept to a minimum on account of the strength of the base. In European installations, no special transporting vehicles were used. Ordinary dump trucks hauled the mixes to the site without segregation. Styropor without asphalt topping developed sufficient strength in the first 24 hours to carry trucks. After 5 days, all construction vehicles could be used, which made the employment of standard asphalting equipment possible. Hot bituminous mixes were placed directly on Styropor. The polystyrene beads melted and fused to a depth of 1/8 to 1/4 inch, thus providing an extremely good mechanical bond between -14- Styropor and Asphalt~ In railroad construction for trains with speeds up to 190 m/hr. similar test sections were built in Germany. Six inches of Styropor were placed directly on undisturbed ground. Then prestressed concrete slabs, to which the rails were attached, were grouted on to the Styropor. No ties were used. -15- Conclus ion Sufficient evidence is available to warrant a thorough study of the adaptability of Styropor for insulating load-bearing arctic construction° Conservation-wise this material can minimize the effects of men's needs on the ecology of the arctic area. True Arctic (on-site) field tests will be necessary to explore, evaluate and resolve the various unknown factors pertinent to or caused by Arctic conditions. Only experfence gathered through these on-site tests can determine the scope of usage. Once. feasibility is established for the corridor conception, road and railroad construction can start in the south with conventional materials gradually changing over to Styropor, thus leaving a finished supply line behind which will be the only economical way of getting necessary materials to the north without damaging the land excessively. Simultaneous studies by oil companies on the use of Styropor. for drilling pads may resolve problems cauSed by the flow of hot oil through perma- frost. The buoyancy of Styropor will be able to hold the pad in its original position, regardless whether the ground ~underneath is solid, or semiliquid on account of thawing action. Numerous holes could then be drilled from a single platform. Research cooperation between Federal, State, and private interests is essential for all to obtain the knowledge necessary for their specific applica- tions in order to keep~ cost at a minimum. PRUDHOE BAY FIELD RULES HEARING November 13, 1969 ATLANTIC RICHFIELD TESTIMONY c.o, ~-5 ATLANTIC RICHFIELD COMPANY BP ALASKA, INC. HUMBLE OIL & REFINING COMPANY RECOMMENDED PRUDHOE BAY FIELD RULES NOW, TI-IEREFORE, it is ordered that the rules hereinafter set forth apply to the areas described in ADL numbers' 25516 28262 28313 34626 25518 28263 28314 34627 25626 28264 28315 34628 25637 28265 28316 .34629 25638 28266 28320 34630 25649 28275 28321 34631 25650 28276 28322 34632 25661 28277 28323 34633 25906 28278 28324 34634 28231 28279 28325 34635 28232 27280 28326 34636 28233 27281 28327 47437 28234 28282 28328 47438 28235 28283 28329 47442 28236 28284 28330 47443 28237 28285 '28331 47444 28238 28286 28332 47445 28239 28287 28333 47446 28240 28288 28334 47447 28241 28289 28335 47448 28242 28290 28337 47449 28243 28297 28338 47450 28244 28298 28339 47451 28245 28299 28340 47452 28246 28300 28341 47453 28247 28301 28342 47454 28248 28302 28343 47455 28253 28303 28344 47463 28254 28304 28345 47464 28255 28305 28346 47465 28256 28306 28347 47466 28257 28307 28348 47467 28258 28308 28349 47468 28259 28309 34622 47469 28260 28310 34623 47470 28261 28311 34624 47471 28312 34625 47472 47473 47474 47475 47476 47477 47482 47483 47502 47503 47504 47505 47506 47507 47508 47509 47512 47513 47514 47515 47532 47533 which areas together with any. extension of pools defined in Rule 1 or pursuant to RuleJ~ are defined as the Prudhoe Bay Field. An outline of the described area is shown on Exhibit 1 of this order. Rule 1 - Definition of Pools a) The Prudhoe Bay Sand Pool is defined as the accumulation of oil and/or gas common to and which correlates with the accu- mulation found in the Atlantic Richfield - ttumble Prudhoe Bay State No. 1 well between the depths of 8,110 feet and 8,680 feet. b) The Prudhoe Bay Lisburne Pool is defined as the accumu- lation of oil and/or gas common to and which correlates with the accumulation found in the Atlantic Richfield - Humble Prudhoe Bay State No. 1 well between the depths of 8,785 feet and 10,450 feet. c) The Prudhoe Bay Kuparuk River Pool is defined as the accumulation of oil and/or gas common to and which correlates with the accumulation found in the Mobil - Phillips North Kuparuk State No. 1 well between the depths of 6,765 feet and 7,060 feet. · Rule 2 - S.~acing Density Not more than one (1) completed oil or gas ~vell shall be allowed in each pool on any governmental section or governmental lot corresponding thereto. Rule 3 - Spacing Footage a) Oil or gas wells may be closer than $00 feet to any property line of the lease except that no well shall be completed closer than 500 feet from a lease line where ownership changes. b) No well shall be completed closer than 1,000 feet to any well drilling to or capable of producing oil or gas from the same pool. Rule 4 - Casing and Cementing Reguirements (a) Before drilling a well or wells in the Prudhoe Bay Field, an operator shall submit and receive approval of a casing program design and cementing practice to provide adequate protection (1) .of all sands and (2) from any pressure that may be encountered. (b) Those wells which the operator intends to use for sustained production or injection of warm fluids shall be protected to the satisfaction of the Committee against permafrost conditions. Unless casing and cementing practices conform to Statewide rules, approval shall be determined as provided in Rule 10 hereof for such programs and practices not previously approved. (c) Production casing shall be landed through the completion zone and cement shall cover and extend to at least 500 feet above each hydrocarbon-bearing formation which is potentially productive. If no hydrocarbon-bearing formation exists that is potentially productive in the interval between the shoe of the next shallower casing set and the cement top as cited above, then stage cementing will not be required ~o tie in the shoe of such shallower casing. (1) Alternately to 4 (c) above, a casing string may be set and adequately cemented at an intermediate point and a liner landed through the completion zone. If such a liner is run, the casing and liner shall overlap by at least 100 feet, and the annular space behind the liner shall be filled with cement to at least 100 feet above the casing shoe, or the top of the liner shall be squeezed with sufficient cement to provide at least 100 feet of cement bet- ween the liner and casing annulus. Cement must cover all potentially productive intervals behind the liner. (2) Alternately to 4 (c) (1) above, the productive in'terval may be completed as an "open hole com- pletion'' or a liner placed and left uncemented if casing is set and adequately cemented not more than 200 feet above the completion zone. d) Casing (or liner), after being cemented, shall be satis- factorily tested to not less than 50% of minimum internal yield pressure, or 1,500 pounds per square inch, whichever is less. Rule 5 - Blowout Prevention Equ.i. pment and Practice (a) All drilling wells shall have blowout preventer equipment which shall include (i.] one remotely controlled blowout preventer installed on the surface casing and (ii) before drilling the Prudhoe Bay Kuparuk River Pool or deeper zones, three remotely controlled blowout preventers, including one equipped with pipe rams, one with blind rams and one bag type. All preventer equipment described in (i) and (ii) shall include (1) a drilling spool with 3" minimum side outlets (if not on the blowout preventer l)ody), (2) choke manifold, and (3) a fill up line. All equipment during this phase of the operation shall have a minimum working pressure capable of withstanding formation pressures normally expected in this area at the depth being drilled. The drilling string will contain two valves (one above and one' below the kelly) during all circulating opera- '~ tions with the kelly. Two emergency valves will be conveniently located on the drilling floor with rotary subs for all connections' in use, one valve to be an "inside blowout preventer" of the spring-loaded valve type and the second to be of the manually- operated ball valve type. b) All blowout preventer rams and choke manifolds will be tested to manufacturers' recommended working pressure when installed and once each week thereafter. Bag type preventers will be tested to ensure adequate operation and working pressure when installed and once each week thereafter. · c) All blowout preventer equipment shall be adequately pro- tected to ensure reliable operation under the existing weather conditions. Ail ram type equipment will be checked for opera- tional functioning and ice buildup before each trip. Rule 6 - Automatic Shut-in Equipment Bach well capable of flowing shall be equipped with a suitable safety valve installed not less than 200 feet below the surface which will automatically shut in the well if uncontrolled flow Occurs. Rule 7 - Bottom ltole Prep_sure Surveys. A key well bottom hole pressure survey shall be made in the pools subject to these rules upon Committee request; provided, however, that such surveys shall not be required more often than once prior to production and once each year after produc- tion commences. The type tests, time, length of survey, number and location of wells, datum and other details will be deter- mined by the operators after consultation with the Committee. Rule 8 - Gas-Oil Ratio Tests After production commences from a pool, periodic production tests shall be taken on all producing wells. These shall be at normal production rates, and shall be of sufficient duration, not to exceed 24 hours, to provide e~ficient mea- surement of the producing gas-oil ratio. Such tests shall be made during the months of June or July and the results will be reported on Form P-9 by the end of August of each year. The requirements of this rule will be waived if monthly reported oil and gas production is based on a gas- oil ratio test made at least every six months by the operator. Rule 9 - Administrat'ive Approval At the request of an operator, administrative approval of a testing or emergency operating periOd may be granted to per- mit existing wells to produce as exceptions to Section 2159 of the Oil and Gas Conservation Regulations. Such approval shall be determined as provided in Rule 10 hereof and shall not exceed six month~ for any well on any one request. Rule 10 - Hearings Any operator who makes application for exceptions to these rules or to statewide rules applicable to this area or for approvals as required by either Rule 4 or Rule 9 hereof shall notify all other operators in the Field'Rules arena of this request. The Committee will give notice as provided in AS 31.05.050 and will cause notice of the matter to be published in an appropriate newspaper. The notice will provide the essential details of the requested order, and will set forth the date, time and place of a hearing to be held, if such hearing is supported by proper protest and request. A protest and request for hearing may be filed with the Committee at its office in Anchorage, Alaska within ten days of the publication date by any party who may be aggrieved by the requested order if issued. If such protest is timely filed, a hearing may be held after the end of the 10-day pro- test period on the date and time specified in the notice. If .no protest is timely filed, issuance of the order will be considered by the Committee without a hearing. Rule 11 - Extension of Rules to Other Pools The rules prescribed in this order shall apply to all pools in the Prudhoe Bay Field. Prior to the time an operator undertakes to develop and produce any pool or pools other than those defined in Rule 1, said operator shall request a hearing to be called to define the pool or pools. 'Company · ; ..~. 1C0-,, i"ewYork, ' ' ''''~ Tclo.2','~on9 212 )'SS 2345 , T. F. 3radsha'.',, · Pre~,id~nt · · Aug~st 6, 19~9 BP Oil Corporation 620 Fiftlz Avenue New York, Ne~v York 10020 Humble Oil &.Refining Company P. O. Box 2180 Houston, Texas 77001 '0 Re: Proposed Cooperative Development . Prudhoe Bay Field Gentlemen: In order to promote conservation, to increase ultimate recovery, to eliminate unnecessary . drilling, to avoid waste, and to insure each participant a reasonable opportmnity to recover its fail' share of the oil and §'a~ in place, it appears desi~-able to us that the oil and gas interval sand belly which was 'el'~counlered in Prudhoe Bay State No. 1 Well bet~veen the depths of $, 066 feet subsea and the top of the · Carbonate formation at 8,747 feet subsea as determined by reference to dual induction log of said well dated March 9, 1965, and furnished the par~ics hereto underlying the unit area out- lined on the plat attached, hereto as'Exhibit A -. be deve!eped, 'opera/cd and produced as if the }mit area had been included in a single lease· Ac-.. cordin.~ly, we propose that appropriate legal-and unitization committees be appointed to commence work immediately after the next competitive State lease sale (e×~ectcd about September 11, 1969) to agree on de£initive forms' of a Unit Agreement and a Unit Operating Agreemcnt which would, among other things: 1. Establish separate participating areas for thc oil rim and tho gas cap each with sepa- rb. tc ownerships within thd ',' :' .,n.. ~rea based on , ,~;RichlieIdCompany · ~ · oil ori2jnally in place nnd gas oriainally in Place with each tract in each partici- pating area being allocated its appropriate percenlage o£ production under the Unit Agreement and with each tract workin$' interest ox~a~er bearing the royalties, overriding royalties and production payments on produc- tion allocated to the particular tract and other lease burdens applicable to such tract. Any . lease covering lands within the E>'~ibit area proven to be productive in the same sand interval and subsequently acquired by any party hereto may be added to tha unit on the same basis. Each participant shall take · its share of the oil and ~as in kind and . · separately shall dispose of its share of the production. In any event the benefit of discovery royalty on production allocated ' · to the lease on xvhich Prudhoe Bay State "- · . · No.. 1 ~vell was drilled shall be shared equally by Humble and Atlantic' Richfield.. · 2. Make initial separate determination of oil and gas originally in place ~mderlying separate, ly ox~med.traets included within the unit area outlined on 'Exhibit A, by April 1, 1970, ' based on data available as of September 30, 1959 and another separate det'armination of oil and gas originally in plae. e underlying separately owned tracts included within the unit area outlined on Exhibit A, by January 1, 1973, utilizing data- available as of July 1, 1972. A final and '- sepai-ate determination of oil and gas ori§-i~ally in place underlyinog the separately o<xmed tracts included within the unit arco, will be made by January 1, 1976. 3. Each party shall consult ~vith other parties hereto as to location and projected depths to be drilled on all wells projected for completion in the. subject sand in order to assure an orderly develop- ment of the field in accordance with sound eng'~- neerin~ principles. Notwithstanding anything herein · · --3 '"" ' to tho contrary, each party at its sole risk, cos~ and expense shall bo free ~o develop its own lcnsos with whatever drilling.or other activity it alone sees fit. It is contemplated that the unit agreement and the unit operating agreement make appropriate investment adjustment as to such prior expenditures, however, the unit shall not be necessarily obligated to pay for wells no~ agreed upon by the above consultation. ' .. 4:. Permit the o~vners of the oil rim participating area to si})re, at their sole cost, risk and expense, solution gas. in the gas cap or in another appropriate sand underlying uni~ area. Since a given well sirhult~neo(is'!y may produce oil, solution gas, and gas cap gas, a formula will be included in the operating agree- ment setting out a method of separately measuring and accounting for such products where that condition occurS.' 5. Provid~ ~or possible exP,%nsion of the unit area and revision of the participating oil rim and gas cap areas, on the basis of oil and gas respectively originally in place, with provisions for handling investment adjustments, prior production.and other relevant ~atters upon expansi'dn and revision. 6. Provide for more than one Operator, with BP being one of the operators... · ?. I:h-ovide for. formulas that will allocate the relative production from the gas cap and the oil rim. .- 8. The participants in the oil rim partici- pating area agree to thc objective of cov~lopm~n~ of the field as quickly as is economically prudent so as to permit each such participant a level of 'D .' offtakc not later than January, 1976 of at least 'three percent (3/%) annually of the oil originally in place under the leases presently ovmcd or to be obtained by each of the participants within the unit area. - All the foregoing is subject to valid rules and reg'~dations of the State Re~tlatory Agency having jurisdiction and to applicable laws, rules and reg-alations of the State of Alaska and the -' Government of ihe United States. If the above is in accQrdance with your understand- ing, please execute and return to us one copy of this letter. .. · Yours very truly, '. ' T.F. Bradshaw . ACCEPTED A'ND AGREED TO TFB/sa .,,TX: lluI, I DII~ 9 '75 2.8255 · E._:XII IB 2T · ' ~a ."."'~ ';~ 8-75' ..,=-?$ "8-rs 9-7~ 19-7s lB-TS { 3--77 J,'~ _~1'"' ).~.,~, ! J '":, .. ', . .... j . i. ,,. -75 /8-75 $'-75 ~-75 9-75 -! 75 ATLAh, T~¢ ~ 18 -?$ 4 J 26288 ~TLANTIC j uC~lL j Pki~LJPS . . _ 2 8 290 . .............. i ~,.. Z, ,: 654 8 -75 23343 9-75 9-7b $.75 _ ,-¢ -: l,-,, 0-,, ~2E..,30 !..~,~'',"" . __,28332 28346 ,T----:I,,:~;: ---l.~.- !.; ~, " %,?s 't8-?s D-?s ,0-75' ,-'ts ' !9-75 2P~329 ~,~.u I L PHILLIPS 8-75 J 8 -75 2829I _ . . UOO,L 8-75 783 $0 Pn.LLIP$ 8 -75 28351 ,. Oc!obe, r 29, 1969 CiilllOrnl. ~,~,m~...:,.,., 0ii Company of ":'~ - '" :) O. i3ox '" San Prancisco, California 94120 Phillips Petroleum Company iSO0" ..... ~cu~} Life Building' Denver, Colorado S0202 ..i. ~. ~.- ~ Mooil Oil Corporation 6'~') Plower Street lies Angeles, California 90054 i:lunt Petrolelull Corporation 900 Pirst National TM ' Dallas, Texas imerada-Hess 'P. O. ~ox 2040 ?..'~ ~.., ~, Oklahoma 74102 Oe'.~ty Oil Company P. O. Box 1404 ~" ' o" ~ Texas 7,00~ Louisiana Lane & ~iim~or,,tion Co. P. O. Box 80350 '~ ,-' .... ~ Louisiana 70180 New O~ !~,,~, ~u~z a~.~..~ Oil Company o09 South ~,i~a~ay, O~ilo 45840 Ne: Proposed Cooperative Pru~aoe lBay Field You each have bean furnis!led with ie'gz~r of in~en~ aatea .-iusas. g, legs by and between the undersigaed, looking forward to ..... ~,,,~.~o..~:'~' ~'~'~": '" of z~ie" ZO'r~,l.~.O,. &~ S, ~z .~ 7 fOOt '~ ......' ....... ' ...... .... ; .... -,~O~ ..... ..,. . . . z ..... ~ ). You each hereby arc g~ven an oppor~mz~y to ]ofn v.,i~?; us the unitization project which is the subject ma'~er of ~hat letter, wlth when dofiuei, will ~ ~ ~'"~ .... ':'" ' ' a '~":~';, ~.~--o. area(s). cap p,.z ..... 2~*,,~ area or c.o,.~.= tie ~'-~':' of .... ~" -~':" .... " ~.. ~ ~z., .,. ~. ~ hereto as ,~,.:,.~...;.-;.-.~r..~.~..;-.~o.~ ... ~...~.~,~ i,~ea,,;., sucll area(s) may ~ ~jus,.,~, a'~ th.~ times pro~dod ~'~ ..... "~ ........ '~', '-'~"':'~.,'.,-:~ such' ~.~.,,.,.~,~= ..... =~,.~"~ b~ and is hereby ame~Ided yo~ &S ~ ~"~""' ~,~ ~y n~z'ezo witii the ~.. so mm. ended hsd oeen execu~e~ ~c/o~ of us; ~ ...... ~~ in ~00~ "~¢~'"~ .... ~'~'~ ' iz~:-t!on ir~ accozdsm~ with ...... ~?~ .... ~"; ,~ ........ "' '""' ~' ~' .... ~": ..... t .... ~o~ not .... pt'OYeS ..... ~- '--~" -~- ' ..... ,-~-,-~ +'k.: ...... - ....... :--- ' ..... (or the !et'tar ofz.~S~s~ .......... a,'" 19~a'u/ ~s constPued as a waiver 'by ii'ay ., ' ..... .... "tO "b~S .............. ~ '" ' ' " you ~o anyona who has uo~ -~.~/:!:is ........ { ~"~ O~ '"" ~ ' .... ~ """"~"~'"' '~'"';' " Our O: ........... . e., "" is antici'gatod "~-,",+ ',,x:b!ic announccn~cnt of thc 'unit will bo made at ' ' Field 2ulcs ~ ..... '"'~' commi'~'tces are being formod and rccommcndation for handling of If you ",' ...... ~ ,,..~. ow to. join wRh us, ana w~'::i*, such. of ~;~ other~..~,,~,~'~"~.,= of t~'is~, letter as,.oz ~° ...... to join, fil tho u~ae~ ~kmo'~ -~ .... ~- o- ~o~i'~ .... lo~'~ ~, ~ in saz~'" -~o%r'r~ ~ , as hereiu muendcd, p!case so indic:t4e by executing and by :..~+~.,.,~,_~. ~,.,..,~ copy of this letter to each of ~"-~:~= "m.a~ ;'~- .... ~a~.~a..~-x~-~ ~.,,~ .... a'o'or¢c:a'6o your reply to this ].et:er by November LO but fn any eveut 'aot ~"~" .....~'~ .... ~.. ~:-2 january i, i970. · P. O. Box28'°' Do,'r~. Texas 75221 ~Y P. O. Box 2130 ':"~"£ton,.~,~ Texas 7700i Oe':;obor '2 9, ~3t3 AND AGREED TO I%'iO~iL,~"'"~"~' COR?ORATION By ~y u'.::, ~ ~ ~ OiL CONiPANY ._ ~ ........... .~ ......." .... ~ -'--.'-'~ .' ~-~:~..:..'...c-~]ZCz?:~'.:¥-..~- .*d:_.-~-2~Z//_-_¢.'-'_/.~/~?~/,///.~.?.'~/~ I _.J_ - ~ ' ~ I · . · ! .... I ! 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J -.'-- -. ~' I ' ' ........ :-': '- ',-' - -.':¢ '-:.k --.-;', .'-1 ['. ; - · ." TESTIMONY OF B. C. ANDERSON SPACING DENSITY AND SPACING FOOTAGE We request that not more than one completed oil or gas well be allowed in each pool on any governmental section. We also request that wells may be completed no closer than 500 feet to a lease line where ownership changes and that a well can be completed no closer than 1,000 feet to another well in the same pool. Illustration 1 shows several sections of approximately 640 acres with each side being about one mile long. (Point these out on the illustration.) State leases on the Slope have been four section blocks. (Point out on illustration.) Our proposal would allow no more than one well per section in each pool. We do not want to leave the impression that every section will need to be drilled, but simply that of those sections an operator feels should be drilled, no more than one well should be allowed per section at this time. At the present early stage of development in the Prudhoe Bay Field, one of the most important things that can be accomplished is to prevent waste by ensuring that unnecessary wells are not drilled. The best way to accomplish this is to simply adopt the generally accepted concept that it is better to drill on wide spacing and possibly find that you need to add wells later than it is to drill on too close a spacing and find that you have drilled unnecessary wells. It is a simple matter to add any wells needed 'later but, obviously, it is impossible to eliminate an unnecessary well after it has been drilled. In addition to the prevention of waste in unnecessary drilling, some of the current objectives in the drilling in Prudhoe Bay Field are to efficiently delineate the field, to provide data needed to Page 2 - Spacing Density and Spacing Footage establish equities for pools that may be unitized, to provide reservoir data needed for.more detailed development studies, and to provide wells to meet the early producing rate requirements from the field. We believe that the proposed well density limitation of not more than one well per section will best provide for all the present objectives. In regard to the footage requirements, our recommendation is essentially the same as the statewide provision for distances between oil wells. Illustration 2 shows the same sections we had in our previous illustration. We now show two boundaries where ownership changes. (Point out on illustration.) Wells could be completed no closer than 500 feet to these boundaries. Wells could be drilled closer than 500 feet to internal section lines on a lease (point out 5), and they could also be drilled closer than 500 feet to the boundary of two leases which have the same ownerships. (Point out 3 and 4.) These footage requirements used with the recommended well density give the flexibility that is needed to locate wells in the best structural positions and in the thickest part of the oil column. This will mean that operators will be able to position their wells so as to efficiently recover the oil with the fewest number of wells. Without this degree of flexibility, we feel that many location exceptions may be needed for the operators to be able to locate wells as favorably as possible. An additional factor to be considered in connection with the footage requirements of well spacing is that many of the wells in the Prudhoe Bay Field will be directionally drilled. Directional drilling is important in this area in protecting ecology as well as in the interest of economy~ The proposed footage requirements will be helpful Page 3 - Spacing Density and Spacing Footage in giving the operators latitude needed for directional drilling targets. Illustration 3 pictorally shows a directionally drilled well cutting the productive sand at an angle. (Point out on the illustration.) The projection of the productive interval of this well back to the map surface is a line and not a point as it is in a vertical hole. (Point out on the illustration.) The line can easily be several hundred feet long where the sand is thick and the drilling angle is steep. It should be noted that in application to directional holes, the prescribed distances apply to the closest point on the productive interval. This is shown on illustration 4. (Point out the distance between 1 and 2 and the closest point of 6 on the illustration.) It can be seen from this simple illustration that the average distance between the productive interval of two wells (again point to 1 and 2) or the average distance from the productive interval and a lease line where ownership changes would usually be somewhat greater than this minimum distance even when the well is positioned as close as possible. I would like to point out that in connection with the Prudhoe Bay Sand Pool which is in the process of being unitized, no spacing restrictions will be needed after unitization. At the time of unitization, we will want to make provisions that would allow the operators to drill the required number of wells and be able to drill at any locations needed to most efficiently and economically drain the reservoir. In addition to the Prudhoe Bay Sand Pool, I think that it is also reasonable to expect that other pools in the Prudhoe Bay Field may also be unitized as development progresses. Page 5 - Automatic Shut-In Equipment safety requirement should be extended to the Prudhoe Bay Field. We propose a rule requiring that each well capable of flowing shall be equipped with a suitable safety valve installed not less than 200 feet below the surface which will automatically shut in the well if uncontrolled flow occurs. Bottom Hole Pressure Surveys We propose that a key well bottom hole pressure survey shall be made in the pools subject to these rules upon Committee request. We would like to provide that surveys shall be required no more often than once prior to production and once each year after production commences. We feel that the type of tests, the time when they are to be taken, the length of survey, the location of key wells, determination of reservoir datum, and other details of these surveys should be determined by the operators after consultation with the Committee. The proposed surveys will provide the Committee and other operators . with sufficient reservoir pressure data to properly monitor reservoir performance. Gas-Oil Ratio Tests After production commences from a pool, periodic production tests should be taken on all producing wells in that pool. These tests should be taken at normal producing rates to ensure that the measured gas-oil ratio is representative. The tests should be of sufficient duration, but not to exceed 24 hours, to provide efficient measurement of the gas-oil ratio. These tests should be made and reported to the State once a year. However, we re'commend that the rule to make and report these special tests should be waived if monthly reported oil and gas production is based on a gas-oil ratio test made at least once Page 4 - Spacing Density and Spacing Footage We want to point out that probably more is known at this time about the Prudhoe Bay Sand Pool than the other pools being discussed here today. The reservoir size, rock characteristics, reservoir fluids, expected reservoir performance, and the ultimate development requirements are not clearly defined at this time and may prove to be quite different for the varioUs pools. However, the limited knowledge of all the pools only gives emphasis to the need to proceed initially to define each pool with a wide spacing program in order to avoid waste. We feel that because all pools in the Prudhoe Bay Field are at a very early'stage of development and the objectives are essentially the same for each, the rules adopted should be applied to all pools. We are proposing that the spacing rules that I have just discussed as well as all other Prudhoe Bay Field rules should apply to the pools defined here today and also to the extension of any of these pools° In addition, these rules should also apply to any other pools that are later developed in the Prudhoe Bay Field. Our proposal is to require that prior to the time an operator undertakes to develop and produce any pool other than those already defined, the operator is required to request a hearing to be called to define the poolo Automatic Shut-In Equipment As you know, Section 2164 of the State regulations now requires that automatic shut-in equipment must be provided in wells completed in or over a body of water. We feel that the obvious problems of coping with emergency conditions on the North Slope indicate that this Page 6 - Gas-Oil Ratio Tests every six months by the operator. Monthly comparison of oil and gas production reports by flow station will be an effective tool in spotlighting a change in the producing characteristics of the wells. The proposed rule will provide the Committee and other operators with the needed occasional check on the performance characteristics of each well. Administrative Approval We are requesting that an operator may be granted administra- tive approval of an exception to Section 2159. This exception would allow the operator to produce a high gas-oil ratio well in excess of the rates provided in 2159 for a period not to exceed six months. The purpose of the exception would be to allow an operator to conduct special tests or provide fuel under emergency conditions. In the arctic, survival and continued operation are especially dependent on adequate fuel supplies. We feel that it is important that operators'be allowed to back up fuel systems with a dependable source of gas fuel. Illustration I State Lease Boundary ~--- Approx, I Mile---~ I Section 640 Acs. '+_ Sections) One One Well Well Limit limit ,per Pool per Pool One Well Limit One One One Well Well Well Limit £imit limit Pool per Pool per Pool Illustration ,, I ~500" ~f Drill Site !'5 Lease t{'ne Where Ownership Changes Illustration ~ I I 4 ,'1'-- /') I / I Illustration ~ Interval' Drill Slle £ease £ine Where. Ownersh~ ~(~) (4) Changes TESTIMONY OF R. E. SMITH CASING AND CEMENTING REQUIREMENTS Permafrost Thaw and Subsidence After the discovery of Prudhoe Bay Oil Field, an evaluation of the possible problems which could possibly be associated with producing oil through permafrost was initiated. As a result of this effort, sufficient understanding of these problems have been obtained to permit design of production wells through permafrost. Recommended design criteria presently being used are considered conservative and with further study can possibly be reduced. What we wish to do today is to summarize results of our efforts to date and outline briefly our future work on this problem. Statement of the Problem To facilitate this discussion, we will state the problem in the context of a conventionally completed well and then break the general problem down into six problem or work areas. To present the problem consider a production well drilled, completed and produced by conventional methods. The surface casing and conductor pipe of this conventional well would be cemented to the permafrost. The surface casing would extend through the permafrost and would be cemented to unfrozen soil and rock strata below the permafrost° Being bonded by cement to soil and rock, the well casing would be held rigidly both axially and laterally below permafrost. As warm oil is produced, permafrost surrounding the well would thaw and subside relative to well casing. Generally speaking, three results are possible° First, this relative movement of soil to well casing could transmit additional loads to casing. Second, thawed permafrost would become a soil again and its support capacity would be reduced. Page 2 - Permafrost Thaw and Subsidence Third, a localized subsidence of the ground surface could occur. The problem, at the beginning of this study, was to determine the extent and probability of these actions and, if found necessary, to design a well configuration which would assure a safe operation. The six problem or work areas are: Permafrost Description - The problem is to obtain sufficient permafrost data to permit evaluation of the above stated problem. If evaluations indicate modifications of conventional methods are necessary, then sufficient data for design of these modifications will be required. Permafrost Thaw - The problem is to predict thaw versus time as a function of permafrost characteristics, both thawed and frozen, temperature and other properties of the production stream, well casing including modified configuration. Subsidence of Thawed Permafrost - The problem is to predict the movement of thawed permafrost as a function of depth and time. Downdrag - The problem is to predict the axial load developed on well casing when thawed permafrost moves relative to casing. Interaction Between Thawed Permafrost and Casing - The problem is to determine the column strength of the well casing in a weak soil. Design of Permafrost Casing - The problem is to consolidate information obtained from the above work areas and determine whether or not conventional well configuration needs modification. If modification is deemed necessary, then the problem is to design a well configuration which will safely function in the permafrost environment. Page 3 - Permafrost Thaw and Subsidence One of the first questions asked in this design effort was, logically, what are the permafrost characteristics of the Prudhoe Bay Field? Mr. Norm E. Hamilia will present a summary of the geologic and ~hermal history of this area. Permafrost Description Mr. Hamilia's Testimony. Several investigations have been made to obtain permafrost data. Briefly, these investigations involved collecting and classifying cuttings from air drilled holes, coring in air drilled holes and testing these cores, and downhole photography. These investigations covered depths to 500 feet. Considerable difficulty was experienced in coring permafrost in this zone due primarily to the fact that this zone is predominantly sandy gravel with some silty sandy gravel. Undisturbed cores (solid unbroken cores) were not obtained in these gravels. Relatively undisturbed cores were obtained in sands and near surface silts. No excess moisture contents were found below 25 feet. Atlantic Richfield, Humble Oil and British Petroleum jointly supported these investigations. Presently British Petroleum is coring permafrost to a target depth of approximately 2,000 feet, the expected maximum depth of permafrost. Atlantic Richfield and Humble Oil are participating in this effort. We are using an oil base refrigerated mud and are coring continuously from 500 feet with a 3 inch diameter core barrel 20 to 30 feet long. Quality cores are being obtained from silts and sands, but only broken cores have been recovered from the gravel zones. Page 4 - Permafrost Thaw and Subsidence As stated above, coring and a siumltaneous testing program are currently in process. To date, no evidence of ice lensing or excess moisture has been found. We are presently coring at a depth of 1,200 feet. Extensive laboratory investigations are planned in conjunction with two or three consultants to determine insitu characteristics. Our best estimate of the depth of permafrost in Prudhoe Bay Oil Field is from 1,800 to 2,000 feet. This estimate is based on well logs, velocity surveys and seismic data. We now turn our attention to the question of permafrost thaw. Dr. T. K. Perkins would like to speak to this point. PERMAFROST THAW Dr. To K. Perkins testimony. Subsidence of Permafrost The movement of thawed permafrost is principally a function of the amount of excess ice in the frozen permafrost. In our case, subsidence around a production well, the depth to diameter ratio of the thawed zone is also a principal factor affecting movement. This can be appreciated by using thaw predictions previously presented by Dr. Perkins° To illustrate this point, consider Figure 1 which shows calgulated thaw zones drawn to scale for various production times. Movements within a thawed zone will be localized due to the arching action (or shear resistance) of the soil against the rigid frozen permafrost which forms the irregular wall of the cylinder. Page 5 - Permafrost Thaw and Subsidence It can be seen that movement occurring throughout a thawed cylinder of permafrost of these relative dimensions, especially during the first ten years or so, will be significantly less than those which would occur if a semi-infinate half spaced was thawed. To illustrate this graphically, consider Figure 2. Here are shown two thawed cylinders. Movement in the cylinder with the large depth to diameter ratio will obviously be less than the movement in the cylinder having a small depth to diameter ratio. The four principal actions which could cause subsidence are underconsolidation, expansion of interstitial waters, ice lensing and surface ice. I wish to briefly consider these actions as they relate to Prudhoe Bay permafrost. Underconsolidation - A soil is underConsolidated when its density is increasing due to natural overburden pressure. If an underconsolidated soil is frozen, upon thawing, consolidation proce§s would commence assuming, of course, sufficient consolidating overburden pressure still exists. Underconsolidation occurs most often in marine clays which are deposited at a rate which does not allow complete consolidation. Another mechanism which could lead to underconsolidation is alternately depositing and freezing soil layers and thereby building up a frozen mass of underconsolidated soil. Geological understanding of the permafrost soils indicates permafrost soils up to within 200 feet of the present thickness, and quite possibly higher, was deposited, then frozen. The remaining 200 feet or less (Gubik) could have been deposited on top of this frozen soil. Hence, underconsolidation of Page 6 - Permafrost Thaw and Subsidence of less than 200 feet is expected. Geological dating of the spores and poiien zs presently being made to identify the various horizons in the permafrost. Interstitial Expansion of Fluids - If interstitial water does not escape while soil is freezing, the soil mass may be expanded up to an amount equalling the expansion of water to ice. Of course, the degree of saturation will influence the amount of expansion of the soil mass. If a soil is less than 92% saturate~ upon freezing. little or no expansion of the soil mass will occur since water would simply be displaced into the gas filled voids. For swelling to occur, the interstitial fluids would have to be held in place with enough pressure to lift the frozen overburden. Comparing the rate of frostline extension during formation of permafrost to time required to force fluids downward through the silty sandy soils, leads to the conclusion that the majority of water could escape downward and negligible expansion should be expected from expansion of interstitial water. A recent publication (August, 1969) by Pieter Hoekstra (Water Movement and Freezing Pressures" Soil Sciences Sodiety of America, Proceedings v~ 33, no. 4, July-August 1969) shows experimentally that water can be driven downward through soil in front of a processing frostline if overburden pressures are of sufficient magnitude. Ice Lensing - The swelling caused by ice lenses is commonly called frost action or frost leave. Considerable experimental and theoretical research has been directed to this complex phenomenon and normally sufficient experience is available to allow safe and practical design Page 7 - Permafrost Thaw and Subsidence of Surface construction. Only recently has experimental work been devoted to ice lensing under large pressures. Hoekstra paper referenced above and P. J. Williams' paper ("Ice Distribution in Permafrost Profiles" Division of Building Research, National Research Council, Ottawa, Canada, April 1968.) address the problem of predicting ice lensing under large pressures. Both theory and experimental data are presented. Based on these two papers and several older works and our knowledge of the permafrost soils, predominantly silts, sands and gravels, we have concluded that little or no ice lenses should be found below 50 feet and at the maximum 200 feet. If clays are found within permafrost, ice lensing is a possibility because of their ability to form ice lenses even under large overburden pressures. Hoekstra demonstrated that ice lensing in clays is primar{ly a function of temperature. Let me illustrate with Figure 3. Hoekstra's experiment is shown schematically here. Experiment involved freezing either a sand, silt, or clay specimen under constant volume in an open system and measuring the maximum swell pressure createdl Hoekstra states from these and previous experiments, 1. "It thus appears that freezing pressure in clays is independent of the type of clay soil used. 2. The difference between granular (silts and clays) and clay type soils can be summarized by stating that in clay soils the pressure is dependent on the temperature at the ice lens, and in granular soils the pressure is independent of temperature." Page 8 - Permafrost Thaw and Subsidence i~.:~ e>~riment~i ~ .... ~_~,~..~how~. ~ere demo~'~.'~ate graphically that ice lens pressure in clays depends on temperature. The maximum swell pressure measured by Hoekstra on silts in an open system was approximately 80 lb/in2. For sands, maximum 'swell pressures were under 20 lb/in2. Using Hoekstra and also confirming data of Rodd and Oertle ("Experimental pressures studies on frost heave mechanisms and the growth-fusion behavior of ice in soils and glaciers" Report No. 515-4-2-66 Conoco, Ponca City, Oklahoma), together with expected permafrost temperatures, we could possibly find ice lensing in clays to a depth of 1,600 feet. The question is how severe a problem is ice lensing in clay. We have the opinion that this problem should be minor because: 1. We have obtained some clayey silt cores at various elevations above 1,000 feet and have found no ice lenses. 2. There is a high probability no thick clay strata will be encountered. 3. Ice lens formed in clays in natural deposits have been reported to be simply segregated non excess ice - Reference P. J. Williams paper reporting cores taken from the Mackenzie Delta to a depth of 400 feet. While Williams found ice lenses in clays to a depth of 400 feet, the moisture contents of the entire clay body was not excessive, between 15 to 20%, which are reasonable for clays at these depths. Page 9 - Permafrost Thaw and Subsidence Surface Ice - Surface ice in the form of ice polygons, pingos, horizontal ice lenses, etc. are readily apparent on the North Slope. These forms of ice will occur only near the surface and will contribute appreciably to the total expected subsidence of the ground surface but will not create downdrag forces. Our present understanding, briefly reviewed above, leads us to conclude that movement of the thawed permafrost should cease around 100 to 200 feet. We are recommending that movement of thawed permafrost be considered to a depth of 500 feet for well casing design. Total expected localized subsidence of the ground surface is expected to be 5.0 to 15 feet. Downdrag Downdrag is the load transmitted by subsiding soil to the well casing. Prediction of its magnitude and distribution as thaw progresses radially outward is difficult. A conservative design value of 2,000 lb/ft2 is presently recommended to a depth of 500 feet. The probability of this magnitude of load is extremely small and we feel with additional investigation, both analytical and experimental, these loads can perhaps be reduced by an order of magnitude. Accepting 2,000 lb/ft2 downdrag, a conventional well will be unsafe and modifications will be necessary. The above 2,000 lb/ft2 downdrag is considered conservative for several reasons. 1. No significant movement is expected below 200 feet. 2. Majority of movement if it occurs will take place early in the production life of the well while the radii of thaw are Page 10 - Permafrost Thaw and Subsidence 10 to 20 feet. Movement will occur under reduced radial and vertical pressures due to the elongated cylinder effect. Also, this movement will not occur simultaneously down the well casing. The type of action anticipated is quite similar to the flow of gravel down the outside casing of a gravel packed water well. 3. Water drainage from excess ice would be vertical along casing and would tend to reduce adhesion of the silts and clayey silts. 4. There is a possibility that tangential arching in the horizontal plane will occur around.the well casing and cause a reduction of the radial stress of soil against the casing. 5. The 2,000 lb/ft2 value was computed on the assumption that a deep (below 300 feet) zone moved a finite distance (several inches to ~a foot) instantaneously. The zone diameter of the sudden movement was assumed to be 50 feet and the soil above it was under total overburden pressures. 6. Preliminary analysis by finite element methods indicates the 2,000 lb/ft2 criterion is conservative. (Report by D'Appohonia - Brooker - Lambe - McClelland, Nov. 11, 1969. Dr. D'Appolonia, author). Interaction of Thawed Permafrost and Well Casing The ability of the well casing to act as a column in extremely soft soil has been verified by a beam-column computer program. Well casing can support its yield load, in an axial sense, without buckling as a column. Page 11 - Permafrost Thaw and Subsidence Design of Permafrost Casing Mr. Frank Schuh would like now to propose a well completion system for this permafrost problem. I Year Top of Perma- frost Thaw Zone of Well Bottom frost TIME OF Pt~ODUCTION 4 Years I$ Years Fig. I Years Thaw Zone around a production well shown to same scale both Vertically and Horizontally A Finite Cylinder of Thawed Permafrost Contrasted To An InfinHe Thawed Zone EKS TRA x RADD ~ OER7 - // -/ 2400 2200 2000 1800 1600 1400 1200 I000 800 soo 400 i. 200 0 0 -2 -4 -6 -8 -I0 -12 -14 -16 -18 -20 TEMPERATURE AT ICE LENS~°C LOAD CELL II CLAY SPEC/MEN · '..'.':.;:'.;,.:: i.'.". :::::::? !.'.: ~///////////. 2.5 cm. DIAMETER ~ -~ -.1.- 5° C CONSTANT Fig. ,~ .. POROUS STONE NOT FROZEN PARTIALLY FROZEN /CE t ENS FROZEN *' ~ CO, OLIN(;-I.2 TO 14.4° C MAxIMUM. PRESSURES CREATED BY ICE LENSING IN CLAYS FROM HOEKSTRA AND RADD - OERTLE 19GG. TESTIMONY OF N. E. HAIMILA CASING AND CEb~NTING REQUIREMENTS Thermal and Geologic History of the North Slope of Alaska as Related To Permafrost Thermal History We are presently in a cycle of glacial and interglacial stages. The present glacial cycles began at the end of the Pliocene epoch, approximately two million years ago and have proceeded through the Pleistocene epoch to recent times. From two million years ago to the present there have been four major glacial stages and three interglacial stages. There have also been minor fluctuations within these stages. At the beginning of the Pleistocene epoch, the temperature of the Arctic Regions declined and precipitation increased at the higher elevations. As the mean annual temperature of the North Slope dropped below 0°C (32°F) the surface layers of the earth began to freeze. With a continued drop in the mean annual temperature, the frost line proceeded deeper into the crust. Because of the natural insulating quality (low conductiVity) of the earth, the advance of the frost line (zero isotherm) was very slow. Birch (1948) indicates that for any temperature change to affect depths of several thousand feet, most of Pleistocene time is 'required. · Throughout the Pleistocene, the climate fluctuated from colder glacial periods to warmer interglacial periods. Ail these effects were impressed upon the temperature profile below the earth's surface. The cooling effect of the depressed mean annual temperature at the earth's surface reaches an equilibrium condition with heat emanating from within the earth. Under steady state conditions, the Page 2 - Thermal History temperature rises with increased depth at a rate determined by the geothermal gradient prevalent in that particular area. An average heat flow for the earth is 1.26 x 10-6cal/cm2sec. From the conductivity of fhe rocks in an area and the heat flow value for that area, a geothermal gradient may be calculated. From theoretical calculations inverse geothermal gradients in the order of 150 feet per degree centigrade are applicable to the North Slope. Inverse geothermal gradients of 78.4 feet per degree centigrade to 133.8 feet per degree centigrade haVe already been measured on the North Slope (McCarthy 1952). The present mean annual temperature near Barrow, Alaska is -12.2°C with a soil temperature of -10.6°C (Brewer 1958). There are indications that the mean annual temperature prior to a hundred years ago was approxmately 4°C lower ~than at present (Lachenbruch and Brewer, 1962) which would result in a Paleo-temperature of about -15°C. With an inverse gradient of 150 feet per degree centigrade, the equilibrium frost line would be 2250 feet below the surface. The frost line penetration and inverse gradient could have been modified in some localities by the effects of thermal blankets such as oceans, glaciers, and large, deep lakes. Under these features the mean annual temperatures approach 0°C and the frost line (base of the permafrost) stands only a few tens of feet below the surface if equilibrium has been obtained. Even smaller lakes affect the frost line to some extent (Fig. 1, Lachenbruch and Brewer, Greene and Marshall 1962). OCEAN HILL 'CREEK SHALLOW LAKE SMALL DEEP LAKE LARGE DEEP LAKE I I Figure 1.* Schematic .representation of the effect of surface features on permafrost distribution at high latitudes. "Figure 1 is a schematic representation of the effect of surface bodies of water on the distribution of permafrost .... Three distinct classes of lakes are represented in Fig. 1. Both the small deep lake and the large deep -lake have mean bottom temperatures greater than 0°C, and perennially unfrozen ground occurs directly beneath them. Beneath the center of the small deep lake, ~ passes through a region of negative values because of the small solid angle the lake subtends at depth, and an enclosed thawed basin occurs. Beneath the center of the large deep lake, effects of the emergent surface are dominated by the effect of the lake, and an unfrozen "chimney" permits communication between the unfrozen ground at depth and the surface. The shallow lake has a water depth appreciably less than the maximum annual ice thickness, and though the mean annual bottom temperature is greater than ,8o' it is less than O°C. Hence it has no perennially unfrozen ground directly beneath it, but like the small deep lake, it causes an indentation in the bottom of permafrost. The shallow creek behaves as a long shallow lake, causing a long indentation in the lower permafrost surface. The effects of the ocean (assumed to have a mean temperature above 0°C) and a hill are also illustrated." (Lachenbruch, Brewer, Greene and Marshall 1962) *New figure number assigned for this presentation. Page 3 - Thermal History There are certain localities on the North Slope that have no appreciable thickness of permafrost below them. GEOLOGICAL HISTORY Prior to the end of the Tertiary period, the western half of the North Slope underwent erosion while in the east sedimentation continued through much of the period in localized basins. At the end of Pliocene times the sea encroached upon the North Slope Plains, depositing the Skull Cliff u~it of the Gubik formation. The Gubik formation is considered to be Pleistocene in age with some possibility of the lowermost part being late Pliocene. In the vicinity of Naval Petroleum Reserve No~ 4, the Gubik formation lies on rocks of Cretaceous age, while east of the Colville River the Gubik lies on rocks of various Tertiary ages. (The extent of the Gubik is shown in Figure II.) ., NPR-4 Co4,///~ \ / mnce oF Wale, ~.~ NoRl'O/ SOUND FIGURE II Index mop of northernAIosko showing Novol Petroleum Reserve No, 4ond oreo of report. {offer U.S.G.S Prof. Popers 302-:303) Exten! of Gubik Forrnotion. ~ 0 Moxirnurn reported lhickness-200 fl, Page 4 - Geological History The Gubik grades upward and laterally from a marine sequence into transitional and fluvial sequences. The maximum reported thickness of the Gubik formation is 200 feet which was recorded in a shothole in the 'southeast corner of Naval Petroleum Reserve No. 4. (Black 1964). The environment of the Gubik formation plus the existence of wave-cut cliffs south of Barrow indicate that seas covered the North Slope plains for much of early Pleistocene times providing a thermal blanket for the area~ These seas retreated gradually to the position of thelpresent c°astline. The above history indicates that the areas near the foothills have. been emergent longest within the Pleistocene and, therefore, should have the thickest permafrost. It also indicates that since the Gubik formation is marine near its base some value less than its maximum thickness must have been deposited while the frost line was penetrating the geologic section. Thaw lakes have established themselves over a large percentage of the North Slope. As they increase in areal extent and depth, the permafrost below their central portions decreases in thickness until equilibrium is reached and no permafrost remains under the lake. At nearly all stages the permafrost thickness is reduced in the vicinity of these lakes. Based on the above thermal and geologic history of the North Slope, sediments below 'the Pleistocene in the Prudhoe Bay Area are considered to have been normally consolidated relative to their environment prior to freezing. The degree of underconsolidation Page 5 - Geological History depends on the thickness of sediments deposited after the permafrost had penetrated a large portion of the total depth. Since the maximum reported thickness of the Pleistocene Gubik is 200 feet and the lower portion is marine, the underconsolidation is equivalent to less than 200 feet of additional overburden. REFERENCES CITED Birch, F., 1948, The effects of Pleistocene climatic variation upon geothermal gradients: Amer. Jour. Science, v. 246, no. 12, p. 729-760. Black, R. F., 1964, Gubik formation of Quaternary age in northern Alaska: United States Geolocical Survey Prof. Paper 302-C. Brewer, M. C., 1958, Some Results of Geothermal Investigations of Permafrost in Northern Alaska, Amer. Geophysical Union Trans. v. 39, no. 1, pp. 19-26 Lachenbruch, A. H. and Brewer, M. C., 1962, (abstract) Geothermal evidence for Recent climatic change near Barrow, Alaska: Geological Soc. Amer. Special Conf. Paper 68, p. 117. Lachenbruch, A. H., Brewer, M. C., Greene, G. W., and Marshall, B. V., 1962, Temperature in permafrost in Temperature -- its measurement and control in science and industry: Reinhold Publ. Corp., New York, V. 3, pt. 1, p. 791-803. MacCarthy, G. R., 1952, Geothermal investigations on the Arctic Slope of Alaska: Amer. Geophysical Union Trans., v. 33, no. 4, p. 589-593. TESTIMONY OF T. K. PERKINS CASING AND CEMENTING REQUIREMENTS Calculation of Thawed Radii Around a Well BOre Radii of thaw around a well bore passing through permafrost have been calculated With the aid of digital computers. In the formulation of this heat transfer problem, three regions are of interest. The first region, shown on Figure 1, is the well bore system which may be composed of several concentric strings of pipe. The annular spaces between the pipes may be filled with gas or with liquids, or they may also contain layers of solid insulation. At the outer extremity of the well bore system, there might also be an annular layer of cement. The modes of heat transfer which we have considered in the well bore .system are: 1. Conduction - which would occur through solids such as insulation, cement or pipe walls. 2. Convection- which would occur within annular spaces filled with a liquid or gas. 3. Radiation - which would occur through annular spaces filled with thermally transparent fluids.. The mathematics which describe these modes of heat transfer are illustrated in Figure 2. This figure shows the equation for steady- state heat flux in an annular segment, it defines the Grashof and Prandtl numbers and shows a convective heat transfer correlation available from the literature (Dropkin and Somerscales 1965, Willhite 1967). This figure also shows the heat flux due to radiatiOn in an annular element (Kern, 1950). The second region of interest, which is shown in Figure 3, is the thawed zone concentric with the well bore system. Outside of this zone lies the third region of interest, frozen permafrost. Heat is carried through or into thawed and frozen permafrost by a Page 2 - Calculation of Thawed Radii Around A Well Bore conduction mode of heat transfer. At the interface between the frozen region and thawed region, heat is being absorbed as ice melts. Figure 4 illustrates two approaches which have been taken in the formulation of computer solutions, viz: 1. The finite difference method. 2. The superposition method. In the finite difference method, the differential equations describing heat flow are written in terms of finite differences, then by. the well known implicit technique of solution, the position of the thawed interface, and temperatures in the well bore system and in'the thawed and frozen regions are calculated as a function of time. An alternate approach has also been studied. The analytical solution for heat loss into the frozen permafrost region is known for constant boundary conditions. Figure 4, for instance, gives the solution for heat flux at the wall of an inner cylinder held at constant temperature (Carslaw and Jaeger, 1947). Since the heat conduction equations are linear, analytical solutions can be super- imposed to handle transient cases such as those we are considering. These two approaches have been compared by calculating radii of thawed zones for a particular set of conditions. Excellent agreement was obtained in that differences in radii of thawing, as calculated by the two programs, were no more than a few inches even after more than twenty years of thawing time. The computer programs have also been checked by comparing computed results with the known analytical solution of a simplified test case. Page 3 - Calculation of Thawed Radii Around A Well Bore T° illustrate the type of results that are calculated, we have chosen two example well bore configurations. At depths less than 500 feet, concentric strings of 9 5/8, 13 3/8 and 20 inch casing were assumed with annular spaces being filled with diesel oil. See Figure 5. Assuming a temperature of 160°F at the inside wall of the 9 5/8 casing and for several permafrost temperatures, thawed radii were calculated for both silt and clayey soil as well as for a gravel or sandy soil. See Figures 6 and 7. For depths in the permafrost greater than 700 feet, an alternate well bore configuration was assumed consisting of 9 5/8 inch casing in 13 3/8 inch casing. See Figure 8. Again the annular space was assumed to be filled with diesel oil and an inside casing wall temperature of 160°F was chosen. For this case, radii of thawing for forty years of production and for several permafrost temperatures. are shown on Figure 9. REFERENCES CITED 1. Dropkin, D., and Somerscales, E., "Heat.Transfer by Natural Convection in Liquids Confined by Two Parallel Plates Which Are Inclined at Various Angles With Respect to the Horizontal," Journal of Heat Transfer, Transactions of ASME, pp. 77-84 (February, 1965). 2. Willhite, G. P., "Over-all Heat Transfer Coefficients in Steam and Hot Water Injection Wells," JPT, 19, pp. 607-615 (May, 1967). 3. Kern, D. Q., Process Heat Transfer, McGraw-Hill Co., New York, 1950. 4. Carslaw, H. S. and Jaeger, J. C., Conduction of Heat in Solids, Oxford at the Clarendon Press, 1947. SKETCH OF WELLBORE CONFIGURATION PROGRAMMED RI R2 R3 R4 R5 R 6 R7 R8 R 9 R I0 RII RI2 FIGURE I FI GURE 2 MODES OF HEAT TRANSFER A. CONDUCTION K (Ti -T ) F = s o c Rc In (Ro/Ri) B. CONVECTION = O. 049 K (G Ke f ,~0' 333 p O. 074 P r r r )$ 2 (R°-Ri P G =~ r ,~ c /~ r K f C. RADIATION 4 4 o-ei (T.~ - To ) r = i+"ri)ro('~ i/ ¢o- ~i'i SKETCH SHOWING TWO ZONES OF INTEREST IN THE FORMATION FIGURE.5 THAWED REGION ' R 12 FROZEN REGION X I- m,I Z -\ FIGURE 4 TWO METHODS Of SOLUTION A. FINITE DIFFERENCE L'I' TI T2 T i T i-I-I B. SUPERPOSITION F ~ 4 (Tw - Tf) K Rw 2 -ku t 2 du (Ru)+ Y 2 ii (Ru)] Figure 5 TYPICAL W~L LBOt?~ CONFIGUt?A T/ON IN P£t?MAFt?OST ABOVE A DEPTH OF 500' "'-" ,.,qTa , '-'* 4~,51b/£t "'-'- 20" . 94 Ib/ft ~ FIGURE 6. CALCULATED RADII OF THAWING FOR SILT OR CLAYEY SOIL I00. 90. 80- 7'0 60 50 40 3O 20 I0 0 0 · ~25° F. 14° F. ~ I I I I I0 20 :30 40 YEARS FIGURE 7. CALCULATED RADII OF THAWING FOR GRAVEL OR SANDY SOIL I00 - 90- 80.. 6o 50- 40- 20,. I0- 0 I '1 I 0 I0 ~:0 30 40 25° E 16° E YEARS Fig ure 8 TYPICAL W~I L B OR~ CONFIGURA T/ON IN PERMAFROST BELOW A DEPTH OF 700' FIGURE 9. CALCULATED RADII OF THAWING FOR SILT OR CLAYEY SOIL' i00. 9o 80- 7o 6o 5o 4o 20 i0 31° F. 23° E 0 0 I0 20 $0 40 YEARS TESTIMONY OF FRANK J. SCHUH CASING AND CEMENTING REQUIREMENTS Slip Joint Method Dr. Perkins and Dr. Smith have thoroughly explained the mechanics of permafrost thaw and subsidence. In essence, they explained that: 1. Sustained production will melt the permafrost a significant distance. from the wellbore. 2. The shallow portion of the permafrost will shrink and subside~when it is melted~ 3. The subsiding permafrost will cause a downward drag force on the casing of an ordinary well completion. Atlantic Richfield's slipjoint method is designed to counteract the maximum possible downdrag forces for the maximum depth of subsidence predicted by our previous witnesses. The concept of the slipjoint method is very simple: The downdrag force of subsiding permafrost is transmitted to the casing by friction of the melted sand and gravel moving downward relative to the casing. If the thawed permafrost did not move, there would be no friction force. And, if the casing moved downward with the thawed permafrost, there would be no friction force. This leads us to three possible methods to counteract the forces of permafrost subsidence: 1. Prevent the downward movement of the permafrost. 2. Design the well caSing to withstand the friction forces of the · subsiding permafrost. Page 2 - Slip Joint Method 3. Neutralize the friction forces by designing the casing to move with the subsiding permafrost. The slipjoint method is an implementation of the third solution. In the slipjoint method, special ca'sing slip joints are installed in the casing string exposed to the permafrost subsidence, and a special wellhead is used that allows the casinghead on the string with the slipjoints to move downward with the subsiding permafrost while the inner casing strings remain in their original position. The equipment used in the slipjoint method can be best explained by referring to a series of schematics of a typical completion that uses the method. The first slide shows a sketch of a well using conventional casing and cementing programs and ordinary wellhead equipment on the left. The sketch on the right shows a similar well that uses the slipj oint method. The casing for this conventional well consists of a 30" conductor that would be set at 50' to 100' and cemented to the surface; a 20" conductor that is set at 700' and cemented to the surface; a 13-3/8" surface casing string that would be set at 2,000' to 4,000' and cemented to the surface; and finally a 9-5/8" oil string that is set at total'depth and cemented to 500' above any possibly productive pay sands. The wellheads for the conventional completion would provide a mechanical connection between the 30" and 20" casing and both a mechanical and a pressure tight seal between the 20" and 13-3/8" and between the 13-3/8" and 9-5/8". Page 3 - Slip Joint Method On the well using the slipjoint method, the casing program would be very similar. The 30" conductor would also be set at 50' to 100' and would be Cemented to the surface. To protect for subsidence to a depth of 500', the 20" casing would be set to 700'. The special slipjoints would be installed in the top 500' of the 20" casing that is exposed to the zone of subsidence. The 20" string is run and landed on the 30" head. The bottom 200' of the 20" is then cemented to the formation. No cement is placed across the top 500' of hole because the slipjoints could not function if they were cemented to the hole. The special wellhead is installed at this stage and then the hole for the 13-3/8" casing is drilled. The 13-3/8" casing is cemented from its total depth up to tie back to the 20" casing cement. The 13-3/8" casing is equipped with a sea floor suspension type hanger with wash ports to allow washing out any excess cement in the annulus between 20" slipjoints and the 13-3/8" casing. No cement can be left between the 20" slipjoints and the 13-3/8" casing since cement would prevent the slipjoints from slipping and would transmit subsidence forces on the 20" to the 13-3/8". The 9-5/8" casing would be installed and cemented in the same manner as in the conventional design. _ The slipjoints and the special wellhead must serve a dual purpose: 1. They must provide a pressure tight vessel during the drilling phase° Page 4 - Slip Joint Method 2. They must allow the 20" casing to move downward with the subsiding permafrost during the producing phase. For the special wellhead the two functions are accomplished with an additional flange connection in the wellhead. The flange is bolted closed during the drilling phase so that it is a pressure vessel, and the bolts are released before production is started to permit the 20" head to move downward. On the 20" slipjoints the dual requirements are accomplished by locking the slipjoints in the desired initial position with a shear device that is designed to shear with an axial load of 580,000#. The shear strength of the shear device is carefully controlled during manufacture and can be expected to shear within a 5% range. The shear capacity of 580,000# was carefully selected to provide maximum safety during both the drilling and producing phases. There are two forms of loading on the slipjoint during the .drilling phase. The first is the tension force on the slipjoints while the string is being lowered into the hole. At 700' setting depth the 20" casing string would weigh about 60,000#. The 580,000# shear capacity greatly exceeds the load due to the weight of the string. The second type of loading the slipjoint must withstand is the axial force due to internal pressure. The maximum pressure in a casing string will be at the bottom of the string. This pressure cannot exceed the pressure required to fracture the exposed formation below the casing shoe. The fracture pressure of the formations Page 5 - Slip Joint Method immediately below a 700' casing string is estimated to be about 500 psi. Even if the 20" casing were filled with gas, the maximum pressure across any slipjoint would be no more than the 500 psi fracture pressure. A pressure of 500 psi in a 20" slipjoint would 'generate an axial force of 160,000# on the shear device. The selected shear capacity of 580,000# provides a safety margin of 420,000# over the maximum pressure force of 160,000#. During the producing phase the slipjoint shear device protects the casing from damaging subsidence loads by releasing the slipjoint before the friction loads can get high enough to fail the casing. The 20" casing and slipjoints are equipped with high strength tool joints. The tool joints have an axial strength that significantly exceeds the strength of the pipe body. With these tool joints, 20" 94# H-40 grade casing could withstand axial loads of 1,080,000# · before exceeding the minimum yield strength of H 40 grade material.. The selected shear capacity of 580,000# for the slipjoints provides a margin of safety for the casing of 500,000#. The second major difference between the slipjoint method and a conventional casing and cementing program is the selected limit of 200' of cement on the bottom of the 20" casing string. The maximum pressure that can ever be exerted on a casing string is~limited to the fracture pressure of the weakest formation exposed to the well pressure° The fracture resistance of formations is primarily a function of. depth. Formations at 350' will have fracture pressures of less than half of the fracture pressure of a similar formation at 700'. If we Page 6 - Slip Joint Method cement a casing string set at 700' to the surface but do not get a seal at the bottom of the cement column, the maximum pressure that can be contained by the string could be significantly reduced. For example, if the cement did not produce a seal in the bottom 350' of a 700' string, the internal pressure would be limited by the formation fracture pressure at 350'. For the most hazardous situation when the casing is filled with gas this would result in a pressure capacity of less than half of a 700' string with a seal on the bottom of the cement column. Since the prime purpose of the cement on any casing string set above total depth is its ability to contain pressures during a hazardous situation, it is apparent that we must obtain the seal at the bottom of the cement column in order to obtain the maximum possible internal pressure resistance for the casing string. In the slipjoint method we will cement the bottom 200' of the 20" casing string to the formation. With a pressure seal on the bottom of the cement column, the 20" casing in the slipjoint method will provide the same internal pressure resistance as a conventionally cemented casing string set at the same depth. The principal factors that affect the success of getting a pressure seal at the bottom of a casing string are: the quality of 'the cement, the quantity of the cement that is mixed, the likelihood of contaminating the cement slurry with drilling mud during placement, and the comparative densities between the cement and the mud in the hole~ Page 7 - Slip Joint Method The 200' cement column in the slipjoint method will be placed around the 20" casing shoe through drill pipe and a duplex shoe. This method provides the minimum chance for contamination with drilling mud during placement. Since only a 200' cement column will be used, it is possible to use a heavy slurry without the usual concern of loosing returns with a long column. This permits us to use a high quality Neat cement such as C~ment Fondu for the material. The annular volume of 200' of 26" hole by 20" casing annulus is about 300 ft3. With ordinary cementing equipment it is possible to obtain good slurry properties when mixing as little as 100 ft3 of slurry. For 300 ft3 of slurry, the mixing control should be excellent. After the 13-3/8" casing has been set and cemented, there is no way for the well pressure to reach the 20" casing and slipjoints. After the production casing has been set and cemented, all of the possibly productive zones will be covered with 500' of cement. During production, well pressures are separated from the slipjoints by both the 9-5/8" oil string and the 13-3/8" surface casing. A second requirement of ~the cement at the bottom of the 20" is to provide a mechanical support for the 20" during the producing phase. At this time the cemented portion of the 20" must withstand the subsidence forces on the 20" and the slipjoints. This load will gradually increase until the slipjoint shear device releases a slipjoint and neutralizes the friction force by moving with the subsiding permafrost. The maximum load on the casing will be the 580,000# shear capacity of the slipjoints. The support capacity of Page 8 - Slip Joint Method the cemented pipe is defined by the weakest of (1) the cement to casing bond, (2) the shear strength of the cement, or (3) the shear strength of the formation and cement to formation bond. Of these, the weakest should be the shear strength of the formation. If the shear strength of the formation is as little as 25 psi, 200' of cement in a 26" hole would have a support capacity of 4,900,000#, which greatly exceeds the expected load of 580,000#. The next slide shows schematically how the slipjoints and wellhead will function during subsidence. The sketches are intended to show the top 600' of a well equipped with slipjoints to 500'. The sketch on the lfet shows the well in the drilling phase before subsidence has occurred. None of the slipjoints have been released, and the special wellhead is bolted closed. As.soon as the well is placed on production, the bolts are released on the permafrost flange. This allows the top of the 20" to move downward without pulling the' 13-3/8" and 9-5/8" heads down with it. The second sketch shows the position of the heads after some subsidence has occurred. The first thing that is likely to happen is that the permafrost will slough and essentially fill the annulus between the original hole and the 20" casing. As subsidence continues and the thawed sand and gravel move downward, the frictional drag on the casing increases until a slipjoint is released. At this time the casing above the released slipjoint moves downward until the friction force has been relieved. The subsidence of the ground surface will be filled in with gravel to maintain the original elevation of the drilling pad. After a slipjoint has been released and as the 20" Page 9 - Slip Joint Method head moves down, the 13-3/8" casing changes from a load contributing member to a load support member. During the drilling phase, all of the casing strings are hung in tension and are supported by the 30" conductor. As the 30" is thawed free and the 30" and 20" heads move downward, the 13-3/8" casinghead will move downward until the initial tensile stress on the 13-3/8" casing has been relieved and the compressive stress has increased to the level required to support the wellhead and the inner strings. For an initial hanging load of 100,000# on the 13-3/8" and a 9-5/8" casing and wellhead load of 340,000#, the 13-3/8" casinghead will have to move down 5" in order to become the full support member for itself and the 9-5/8" casing. The maximum stress on 13-3/8" 72# N80 casing that would be generated by this load change would be 21,000 psi, which is only about one-fourth of the minimum yield of the pipe. The third sketch shows the well after considerable subsidence has occurred. As soon as the 20" head has moved enough to open a gap of 2' between the top of the permafrost flange connected to the 13-3/8" and 9-5/8" heads and the bottom of the flange which is connected to the 20", a 2' split extension head will be bolted to the bottom flange. Any number of these extension heads can be used. The principal purpose of the extension heads is to keep the top of the 20" head above the gravel pad. If gravel were permitted to spill into the 20" x 13-3/8" annulus, it would be possible to form a gravel bridge across the 20" x 13-3/8" annulus, and transmit subsidence loads on the 20" to the 13-3/8". Page 10 - Slip Joint Method The last four slides that I have are drawings of the equipment. The first of these is the slipjoint. The slipjoint is designed to permit 10' of shortening or 10' of lengthening. The shear device is a special heat treated aluminum bar that is about 3/8" thick. The pressure seal is provided by two "O" rings. The overall length of the slipjoint is about 37' which is about the same length as our Range 3 casing, making it relatively easy to install. The next three slides show the details of the wellhead that we intend to use with the slipjoint method. This slide shows the configuration of the head during the drilling phase. The permafrost flange is bolted together during the drilling phase. The upper half of the flange is threaded for 2-1/2" acme screws. The bottom flange has 1-3/8" holes for 1-1/4" stud bolts that extend from the bottom of 2-1/2" screws. The flange is rated at 1000 psi W.P. with the nuts made up on the 1-1/4" studs° The 13-3/8" slip suspension is also special. Two sets of slips are used. The upper slips are designed to support the 13-3/8" in tension during the drilling phase and the lower slips support the wellhead and inner strings after the 13-3/8" has become the support member° The next slide shows how the wellhead would appear during the producing'phase after the 20" has moved down a few inches. The slide shows that the 2-1/2" screws have been advanced to be in contact with the lower flange. The 13-3/8" casing can easily support its weight plus the weight of any strings run inside the 13-3/8" casing. The 2-1/2" screws, however, are designed to support the full weight of the 13-3/8" and inner strings. They will only be used to support the 13-3/8" Page 11 - Slip Joint Method during any future workovers. The purpose of placing at least a portion of the load back on the 20" during a workover is to provide additional lateral stability to the wellhead. The last slide shows the wellhead configuration after the 20" has subsided more than 2' and an extension head is bolted to the lower permafrost flange. The extension head is manufactured in three segments and has the same bolt pattern as the lower flange. This permits the 2-1/2" screws to be used for workovers, even after one or more extension heads have been installed. In summary, I would like to state that the slipjoint method represents a reasonable solution to the permafrost problem. The mechanical and pressure containment design 'features of the slip- joint method are in line with, or exceed, normal oil field practice, and provide a margin of safety at least equal to that presently required. The slipjoints provide a margin of safety over the maximum possible forces of subsidence that does not exist in a conventional completion. CONVENTIONAL WELL DESIGN WELL USING SLIP ,JOINT METHOD MAXIMUM ZONE OF SUBSIDENCE SLIP ,JOINTS SEA FLOOR TYPE HANGER Fig u~e I BEFORE SUBSIDENCE DURING SUBSIDENCE LATE STAGES OF SUBSIDENCE Add on Heod8 ,.SHEAR BAR Figure 3 SEAL:; Figure Figure 5 0 In Figure 6 TESTIMONY OF R. W. MC CLESKEY, JR. BLOWOUT PREVENTION EQUIPMENT AND PRACTICE The proposed rule on blowout prevention equipment and practice is more definitive and restrictive than the present Statewide Rules. Statewide rules must, of necessity, b~ written to cover a broad set of conditions. However, where more and better information is available, it is good and common practice to revise the more general rules. Sometimes the revisions are less restrictive; some- times more restrictive. In this case, somewhat greater detail concerning blowout prevention equipment and practice is needed for the protection of the area and its natural resources. Rule 5 requires that one blowout preventer be installed on the surface pipe and that three blowout preventers be installed before drilling the Prudhoe Bay Kuparuk River Pool or deeper zones. All blowout preventers shall be remotely controlled and shall have a minimum working pressure capable of withstanding formation pressure normally expected in the area at the depth being drilled. In practice, this means that the working pressure ratings of the preventers on a drilling well must be occasionally increased as drilling progresses deeper. The rule is specific as to certain components necessary to have "adequate blowout preventers." These components are listed and include 3" minimum side outlets on either a drilling spool or the body of the blowout preventer, a choke manifold, and a fillup line. And since the drill string is normally used with the blowout preventer, it must not be a weak link. Therefore, drill string safety equipment Page 2 - Blowout Prevention Equipment and Practice required includes (1) two safety valves (one above and one below the kelly) during all circulating operations with the kelly, and (2) two different types of emergency valves to be located on the rig ~loor. The rule also defines the BOP test schedule. Ram type preventers and the choke manifold will be tested to the working pressure of the equipment when installed and once each week thereafter. The annular or bag type blowout preventers will be tested on the same schedule to ensure adequate working pressure. Finally, the rule requires that the ram preventer equipment be checked for operational functioning and ice buildup before each trip. TEST IMONY PRESENTED AT THE STATE OF ALASKA PRUDHOE BAY FIELD RULES HEARING by BP ALASKA INC. NOVEMBER 13, 1969 ROBERT STONELEY QUALIFICATIONS FOR EXPERT WITNESS - STATE OF ALASKA · NOVEI~ER 13, 1969 I am the Senior Geologist for BP Alaska Inc. in Anchorage. In 1951, I received the degree of Bachelor of'~rts in Natural Sciences, with Geology as the principal subject, from Cambridge University, England. I was awarded the degree of Master of Arts in 1956. During the winter of 1963/64, I attended the post graduate course in Oilfield Geology at the University of Southern ~California, I was employed between 1951 and 1953 in the antarctic as a member of the .Falkland Islands Dependencies Survey. From 1953, until the present time, I have been employed by the British Petroleum Company and aasociated~ companies. My work has been concerned'with various aspects of petroleum exploration and development in England, East Africa, New Zealand, Alaska.an'di~' . ~.~ Iran. Between 196]. and 1965, I was concerned with exploration in Alaska and spent most of four summers on field surveys in different parts of the State, including the North Slope. I was also responsible for the formulation of exPl0ratory survey and drilling activities. For the past year, I h'ave been resident in. Anchorage, and have spent a portion of my time at Prudhoe Bay, being responSible for geologic~l~"aspects of'the exploration 'o~ BP~!s leases, in the' Prudhoe Bay Field. I am a member of 'the American Association. of 'Petroleum Geol- ogists, and a Fellow of the Geological Society of London W. J. SAINT QUALIFICATIONS FOR EXPERT WITNESS - STATE OF ALASKA NOVEMBER 13, 1969 I am Technical Manager for BP Alaska Inc., Anchorage. In 1951, I received a B.Sc. degree in general Science from the University of Reading, England. In 1967, I received an M.S. degree in Petroleum Engineering from the University of Houston, U.S.A. I commenced work with the oil industry in 1956, with Trinidad Petroleum Development Co. Ltd.,' Trinidad, West Indies, joining BP when the Company subsequently became BP (Trinidad) Ltd. in 1959. I was initially engaged in the oil industry as an Assistant Production Engineer, becoming a Production Superintendent in 1959. I attended the University of Houston during the 1961/62 semester year. I returned to T'rinidad as Reservoir Engineer · and became Chief Petroleum Engineer in 1965. In 1967, I was transferred to BP's Libyan operations as Field Superintendent, becoming Production & Terminal Manager in 1968. This latter post I held until my transfer to BP's operations in Alaska in September, 1969. STATE OF ALASKA HEARING ON PRUDHOE BAY FIELD RULES A CASING DESIGN FOR PRODUCING WELLS COI,-2LETED IN PEI~FROST _AREAS We present a casing design for the completion of wells on the , . North Slope. This design makes provision for the circulation of a cooled fluid between casing strings covering the permafrost. It will allow the temperature of the permafrost t~ be maintained below 32°F during the production or injection of hot fluids, should this prove necessary. In order to determine whether or not refrigeration will be re- . quired when the wells are put on productiOn, an extensive program of work is being undertaken. Included in this is a joint coring program with ARCO and Humble~ and a series of experiments in the field. In these field tests, hot oil will be circulated in holes cased through the permafrost to simulate the production operation. These experi- ments will, give information on any ground subsidence that may occur due to the thawing of the'permafros't, together with some information on the stresses, if any, developed in the casing. The fOllowing drawing shows our proposed casing program. The surface string is set at approximately 2300 feet and cemented to sur- · face. This casing string will cover the permafrost Zone'. A separation sleeve is hung inside the'"'surface casing string at approxinately 2200 feet immediately before running the intermediate string. The inter- mediate casing string will be cemented to approximately 2250 'feet. The'cooling fluid, if required' wili' .be' circulated down the 'annUlar space between the surface casing and the separation sleeve, return~ ing up the separation sleeve --intermediate casing string annUlus. STATE OF ALASKA HEARING ON PRUDHOE BAY FIELD RULES GEOLOGIC TESTIMONY The discovery of oil at Prudhoe Bay by Atlantic Richfield and Humble early in 1968 sparked off an interest in the North Slope that has in no way diminished subsequently. This interest has sustained a vast effort in the field of exploration on the North Slope, which .has resulted not only in the discovery to date of three separate oil pools in the. Prudhoe Bay Field but also in an understanding of the geology of an hitherto unknown area of the NOrth Slope. We should at the outset stress the fact that. today we are con- cerned only with a small corner of. the vast wilderness known as the North Slope (EXHIBIT A). The North Slope is over 600 miles in length from the Canadian border to the Chukchi Sea and up .to 200 miles in width from the Brooks Range to the Arctic Ocean. This area is larger than. all of the New England states taken together and is comparable with the entire state of Colorado. Prudhoe Bay itself lies 120 miles north of the Brooks ~Range and 70 miles from the mountains at their nearest point to the south-east. The field area lies entirely within the flat,~ low-lying coastal plain and the nearest rock · outcrops, of the Tertiary Sagavanirktok' Formation, are .more than BO miles away to the south of Prudhoe Bay. Exploration, therefore, is largely dependent on geophysical methods, supported by well data as they become available. · bUilding upheavals that formed. ·the Brooks Range. The .folding ~attributable"to these, compressive movements dies .out along a line passi{g just north 'of Umiat ~and a few. miles north .of Sagwon. ~The basement to the sedimentary formations · (EX IBZT B) Geologically, the Prudhoe Bay 7ield. lies beyond the range ..of the mountain- of petroleum interest may lie deep beneath the foothills of the Brooks Range, and it rises gradually northwards to a series of very broad and gentle structures near the present coast, referred to collectively as ~he Barrow Arch. Prudhoe Bay is one of these structures. Let us now look at the succession of formations that is found in the Prudhoe Bay area (E~THIBIT C). This Exhibit is a generalized and composite .~. stratigraphic column and does not apply to the succession found in any particular well-. The-figures at the-left are.cumulative thicknesses and should not be ~regarded as well depths. In order to be able to refer to particular parts of this succession, a series of formation names has been used. Although existing t~erms have been employed where possible, the use of any names at the present time should be regarded as informal and not in any .way constituting a scientific proposal. The approximate geologic ages are shown on the right, but considerably more work needs to be done before the beds can be da~ed ~authoritatively. The pre-Upper Devonian basement consists of compressed and steeply dip- .ping shales and sands classified as argillites and quartzitic greywackes. · .. It has .little or no petroleum interest and ..is overlain with strong uncon- formity .by. the. formations that ~are prospective for hydrocarbons. These may be grouped into two sedimentary sequences, which I propose to consider from the. top downwards as this is the order in which they are seen while drilling. The higher of 'the two sequences dips steadily eastwards, so that the uppermost formation thickens' from some .~3,000 to more than 5,000 feet in.going ............ from'~ 'west'~ ~to'"~e'ast~. ' 'This is th~'~S~agavanirktok Forma'tion~, -~ consis~in,g~- oral. gravels sands, silts and clays with the .gravels. becoming much less abunda, nt in the ! '~lowest 2,D00 feet' There' is a transition downwards into the underlying Cretaceous beds, · which, are divisible.into at least two groups. The higher, consisting of sands, siltstones and mudstones with coals which decrease downwards, is broadly correlated with, or referable to the Schrader Bluff Formation, while the lower group, comprised of mudstones, shales~, siltstones and occasional · thin volcanic tuffs, is comparable with the Seabee and Torok Formations as .... seen .at. outcrop· to the south. It is possible .that, later on at Prudhoe Bay, it will become possible to subdivide this latter unit into the two, or per- haps even more, separate formations. The sequence just discussed overlies the lower one unconformably and rests on progressively older members of it .towards the .east. The highest beds of this lower sequence are .very fine to' medium-grained, someWhat fri- able sands interbedded with .mudstones. This unit is up to about 800 feet thick and has been termed the Kuparuk River~ Formation...It passes down into approximately 1,800 feet of mudstones, shales and siltstones, probably referable to the Jurassic Kingak Formation. The most important of the formations that.we are concerned with at Prudhoe Bay underlie the Kingak apparently without any break in deposition. They are primarily Triassic.. in .age and are classified..provisionally as ..the Prudhoe'Bay Group... The highest unit is a fine-grained sandstone 'to siltstone, - characteristically glauconitic and referred to as the Oxytoma Formation, · after one of the fossil pelecypods that it contains. The thickness of this . sand varies..but ~is usually less than 30 feet. The Oxytoma Formation overlies 40 ~150 feet. ·.of shales, limemt*o, nes, and ~phosphatic .rocks ,. contai, ning .abundant fossils and 'closely comparable ~ with the .Shublik .Formation at outcrop. Shublik overlies, with an abrupt contact but apparently· conformably, a very · porous, fine to medium-grained quartz sandstone, in which the grains are often well sorted. This sand, which varies up to some 600 feet in thickness, is thought to correlate with the upper part of the Sad!erochit Formation and forms the most important reservoir rock known to date at Prudhoe Bay. The borehole log correlations of t'he wells that have penetrated 'this sand are good 'and give us every indication at this time. that the reser~zoir is contin- uous over a wide area..The lower part of the sand is conglomeratic and thin ~mudstone interbeds are ·also present. The Sadlerochit sand passes downwards into a shale with thin siltstones. .This unit ranges from 100 to over 200 feet in thickness and may be equivalent o to the lower part of the Sadlerochit Formation in its type area. A thin, highly glauconitic sandstone appears locally downflank at the base. The beds that ~we have juSt been talking about are predominantly sandy ~ but they rest on a series of beds that are mainly carbonates. Ail of the beds beneath the Prudhoe Bay Group. are classified tentatively as the Lisburne Group ~and are believed to be mainly Mississippian and Pennsylvanian in age. The two members of the Lisburne Group both increase steadily in thickness from west to east. The upper member consists of limestones and dolomites with sub.- ordinate shale interbeds, and it passes downwards by loss of the carbonates into a lower member of grey,~ green and 'red shales, indurated quartzites, silt- stones and coals. These beds rest upon the pre-Upper Devonian basement. ~ To summarize, the higher of the~ two sedimentary sequences dips-··fairly regularly eastwards and overlies the older sequence unconformably. This older - * sequence, which contains the reservoir formations that we are concerned with, had been warped into a broad anticlinal nose which plunges approximately west- north-westwards, cut 'by faults of.variable displacement, and planed by erosion prior to the deposition of the overlying beds. EXHIBIT D illustrates these relationships. It is a diagrammatic east-west cross-section through the Prudhoe Bay Field and is ~'ot drawn to scale. It por- trays, the truncation of the lower sequence by.the higher one, in such a manner that more and more beds appear beneath it towards the west. Also shown is the steady increase in thickness of the Lisburne Group to the east. This Exhibit in addition indicates the mode of occurrence of the .hydro- 'carbon pools at Prudhoe Bay.. From top to bottom, these are FIRSTLY in the Kuparuk. River sands in° the western part of the field area, where the oil appears · to be trapped, beneath the .Lower Cretaceous unconformity. · SECONDLY, and by far the most important as known at present, is the accumulation in the Prudhoe Bay sands. This accumulation is the most widespread areally and we are presently regarding it as common between the two sands, although that portion of it con- tained within the 0xytoma Formation is rather insignificant compared with that in the Sadlerochit. This pool is contained within a gently westwards plunging anticlinal nose that has been cut- by faulting, but the actual trapping of the oil and gas is again effected by the Lower Cretaceous unconformity. The THIRD · accumulation, in the Lisburne limestone, is still rather poorly understood. Oil and a little gas have been encountered in wells in the eastern part of the field,-but positive hydrocarbon indications, have been obtained from only a few of the wells that have been drilled at comparable structural elevations .to the west. "The reason for this irregularity is at present uncertain. ~ Once' again the ~ltimat~ trapping mechanism seems, to be provided by the Lower .Cretaceous unconformity. And now we' come to· the definition of' the pools' and to .the outline of the 2 A completion string of casing will be cemented .up to a depth of approximately. 2300 feet and the annular space between the. intermediate and completion ~trings will be filled with an insulating fluid. An · insulating sleeve will be run to a depth of approximately 2500 feet and will be set in the completion string on a packer. The annular space between the insulating sleeve and the co.~pletion string will be filled with an insulating fluid. There are modifications which can be applied to this design with .regard to Casing sizes and cementation. However, the basic principle with regard to maintaining the permafrost below 32°F remains. We' are currently still in the design stage with regard to insu- lating fluids and refrigeration plant's'. We propose to complete wells . in the foregoing manner until such time as some other more economical method is proved equally, satisfactory with regard to well protection against the possibility of permafrost subsidence. We believe that all operators in the Prudhoe Bay area should be giving full consideration to this Possible problem and we hope to see more solutions discussed among operators and offered for consideration in the future. field area. In apparent 6rder of importance the pools are:- a. The Prudhoe Bay Sand Pool (EX}tlBIT E), defined as the accum- ulation of oil and/or gas common to and which correlates with the accum- ulatioh found in the Atlantic Richfield-Humble P. rudhoe Bay State #1 well between the depths of 8,110 and. 8,680 feet. .......... b. .The__]~rudhoe Bay Lisburne Pool (EXi~IBIT F), defined as the accum- uIation 'of oil~·-and/or gas common- to and which 'correlates 'withy the ancum-~ ulation found in the Atlantic Richfield-Humble Prudhoe Bay State #1 well between the depths of 8,785..and 10,450 feet. .· c. The Prudhoe ~Bay Kuparuk River P°ol (EXHIBIT· G), defined as the accumulation of oil and/or gas common to and ·.which. correlates with the .aceumulation found in.the Mobil-Phillips Nor·th Kupa.ruk----State #1 well be- tween.the depths' of 6,765 feet and 7,060 feet. The areas covered by these pools are, in places, not fully defined at .the present time and, in certain directions, require further, delineation by drilling. The maps that we are'about to submit, however, show the areas within which it is reasonable to expect that the pools lie, based on inform- ation presently available A "buffer zone" of. two or more miles has been included locally to cover the areas in which we may expect wells to be · drilled at the margins of the field. . . EXHIBIT H· shows the probable area underlain 'by the Prudhoe Bay Kuparuk · River Pool, together with the currently available well .control East approx- ~imat'ety .of the" Kuparuk River, ~the"~Kuparuk'' River' s'an'ds'are~ abs~ent. ~altogether ...... because of. the truncation .by the L.ower Cretaceous unconformity, . EXHIBIT I' demonstrates ~the currently believed extent of the Prudhoe Bay Lisburne Pool. As already mentioned, the western limit of the accum- ulation is somewhat problematic but the wells in which oil was observed are indicated. · EXHIBIT. J shows the area covering the Prudhoe Bay Sand Pool and in- . corporates the area of. the letter of intent to unitize of August 6th,1969, which has already been submitted to the Committee. Again, the wells that 'provided evidence of the presence of oil are indicated. .The three pools are combined to give the final geolOgic EXHIBIT K, which ~outlines the Prudhoe Bay .Field as composed of the three defined pools. The wells in which oil was present 'are indicated, together with a reference listing the pool or pools in which oil was. discovered. This outline is b.eliev, ed at the present time to cover the area of the Field and is the area, Gentlemen, over Which we are requesting that the proposed Field Rules should apply.. The area is defined by reference to the Alaska Division of Lands numbers of the leases contained within it. This concludes the geologic testimony, and I wish to thank you for your attention. EXHIBIT IA' E XHIBI'T 'B' SOUTH NORTH BROOKS SOUTHERN NORTHERN RANG E FOOTH ILLS FOOTHILLS UMIAT · COASTAL PLAIN ARCTIC OCEAN UPPER CRETACEOUS- TERTIARY LOWER CRETACEOUS- MISSISSIPPIAN BARROW ARCH SCHEMATIC. CROSS - SECTION ACROSS THE NORTH SLOPE EXHiBiT Ici CU MU LATI VE TH ICI, X,N ESS F~ Fi M .AT' I C~ N (I N ?ORIvIAI_ _ ) APP ROXI l',/l,'~J'~ El AGF 0IL GAS -O I000- 3000 - 4000 5000 - ~,000 - 7000 - o o · . (.) i..) 0 G' © 0 0 © 0 (-) © · . (.)' C. C; 8000 9000 .~..! 0000 1000 I~OOO 13000 oas {~1 OIL I-4-O GO i · SA GAYA N I RKTO K .3 000 -5000 SCHRADER ~000 F-T BLUFF / S E,-qBEE / TORO K c. 1800 FT KUP,,~, R"U K RI VE R ~©_~ M xXTT, O. m 0- ~0"-' '._.x FT KI NGAK FORMATION O -- I~OO .x OX Y T_QM.A -~--- SH UB L_ IF,, F'T <-30 F-T o ,- ~' o o :, b ""' SAND 600 FT -'u o _ u c S~LEROCHtT --'- SHALE __~00 FT l -- -~---!~-~--- : __.~...~ .... i ........ ~" i'--= ~-'u' ~ LIMESTONE · i ! - ''" ;' '-~",": ;"-' ".. ~ SAND & SHALE J ARGII LITFZ S & QUATERHAR Y TERTIAf?Y :' RLTACEOUc LOWER CRETA(]EOUS LOWkk' C R hZ TACEOU $ ,J U i:;.~ A S % I (L PRUDHOE L:Z:::~ AY GROUP TRI ...,SIC PE PE NNSY L~ N~A N LISBURNEl ~1-1 PRE-UPPER D F_ ',./ ,...,'"' I" .I i ,A N C. OLUMN OF PRUDHOE BAY AREA N.B. FIGUR. ES AT LEFT ARE ['qL,T DE.PTHS EXHIBIT 'D' WEST SURFACE SAGAVA N IR KTO K EAST PRUDHOE BAY GROUP '"-~-'-~"'"'"'- SCHRADER BLUFF "~'~~..~..... f KUPARUK RIVER KINGAK SEABEE// TOROK SADLEROCHIT SAND WATER SA D--L"~-~ OCHI .... T:~ HALE LISBURNE LIMESTONE OIL SAND/SHALE "ARGILLITES" Presented to: Oil and Gas Conservation Committee Presented by: B,P. A.l.mska ~nCo Conservation Fil, e: "/,~8'3 Dated: NovemL~~ 13, 1969 SCHEMATIC CROSS-SECTiON OF PRUDHOE' BAY FIELD EXHIBIT 'E' __THE_. PRUDHOE BAY SAND POOL ARCO 6100 HUMBLES PRUDHOE BAY STATE i ' 'i PREDOMINANT LITHOLOGIES ~ SH&LE ~. -. ~ ~ StiALE- SANDS'T'ONE 8200 SADI_E-~ocHiT ', - -~- --~ -~- 4 .- 'SANDS 8400 8500 8 6 O0 -- :--- iNDUCTiON THE, .OF~I GIN A~. LATERLOG · DUAL .:" " ,; ; ~ , .~- ' _ PRU'~HOE BAY ~-, i ~ ' :. ;' 'i :~_::~_~~'sA~ POOL ~ '..~ I ~-,.::~~--~ ,, / ',. ~, EXHIBIT IF I EXHIBIT 'G' PRUDHOE BAY! KUPARUK RIVER POOL ~ I .~:--'~ i TYPE LOG OF 'THE PRUDHOE BAY KUPARUK RIVER POOL AS PENETRATED IN MOBIL OIL COMPANYS NORTH KUPARUK STAT 6900 7000 7200 i LEGEND PREDOMINANT LITHOLOGIES - SHALE MUDSTONE j2,///'/j __ SANDS TONE EXHIBIT 'H' ALASKA-NORTH SLOPE PRUDHOE BAY AREA TISN TI2 , ~ ~ t T So::~ I H / I H ~:,~7 ~7~4~ j ~7 - ~ -~'~ [-'-F~/~;~ .... ~' .c:q~7" ~t--'~'~ ~.~ ';,~.~ ~- ~.,~ ~'-':.~:;~-- ~,~ .,~ ............ .~%:~ ........... ~.~/~ .................... ~ ................... ........................ ~s~ ~'~ ~:'g ~:~ ..... ~g T ~'.;~ ..... ~- ' , ...... ~" ~;~- 3~"-,-~ .... ~,' g t ' ;-~ ...... ~-- ~ ~4~ - ' ~ ~--~ 7B137 J :+4636 41502 47503 .............. ~RCO A..~..: ..... ~,~0 PI A H ~,~d PI So MO P'I BP RP ~P PR H3 BP ' ~ E A R .... ~ ..... BP ~' UPA ',ARCO ARCO j~ A H A H Ho PI So ~,Io Pi So sE E~ST, Hn PJ BP BP 8P B A H A H A U A. H B P B .ARCO.' ' H~ST , ~A( mvER I 28345 28~4 414/3 'PU~STI I DEL1Sr~ ARCO U P A ,~ ~h Mo So ............... ARCO A H 47~5--~ .... ~7477 ....... ~'8290 ......... ~ ..... 47415 28314 283L5 IRR ~-33~d ....... ~'~'~- B;~2 26346 26241 47414 41514 515 PR ARCO ARCO ~'~T 3~u~ ~ Z8335 28334 ........ 2 ~'T~ ~{ 2B'J49 283~8 4~533 47532 / ~1-10-16 H P A Am, H ARCO ARCO Sec Co SHn C,IV S Co Sun O~ly S Ch,~mno~on Am H Am H Sec BP ~,1o ~l BP BP BP U P A U P A Penn P~nn 0 MFMI ST '1 .............. t,]o PI A~ H ARCO ARCO ARCO CO S~n~ C, ty S ',;nc Penn ~o SUH C~:y SMD P~ Am H H;n~ U P A U P A U P A UPA UPA ~, UPA UPA ........................................... ................. 0 KAOLER ............... Am H U P AR~O ~ ARCO ARCO Shotmuyel ARCO ARCO ~o PI W DH;ne', ] W S H~shall ~h,~mp~ oH ~hamp~oH [,~o P~ Champion Sholmeve~ ~,~o PI Tex. Sh~l 13N 12N lin TION W W W W W 5. Od ~ SCALE 'MI LES BP BP ALASKA ARCO AILAIITIC RICHFIELD A H ARCO lll31~BLE AmH ANERAOA HESS et al CoS~n~ C~1¥ $ COIIT EIIHL ell SUNOIL CIT ES SERV CE H~ HAMI LIOli et No P~ NOBIL PHILLIPS ~o PI So NOBiL PHiLLiPS SOCAL So SIAIIDARD 8JL OF CALiFOROIA le~ TEXACO U PA UNIOll .PAll AMER ICAN GBHAm GEli~ AL A~ERI~I ~o So JOBIL SOCAL PENN - PENNZOIL~ BP ARCO -- BP ALASKA P.R.~ B.P. PUT RIVER WELL S.D.~B.P. SAG DELTA WELL WELL WITH OIL WELL WITH SANDS ABSENT AREA C.OVER I N G PRUD HOE BAY n "r.N KU PARU K RIVER POOL EXHIBIT "I' ALASKA-NORTH SLOPE PRUDHOE BAY AREA _- ~ ~_ ~ ~ '/~,' '~-~ ~' -~'1 :'~:~ ~4~ ...................... ARCO H NW[I~ I 0 FEN ST ~ N ~P~ ST ~ *__~ ......ftc PI A H Uo Pi So Uo Pm Bp RP ~P P~ I~,,.,~ BP A H ~ A ARCO -- ARCO ~o PLA H A H So ~A ~.~__~ MO PI So BP I BP BP BP A. H A H A R ~ tt A H ...................... ~,., .~, -., ,_,,, ~'- ............... ~ ....... "BOI 28248 .... TB'~'47 ...... T~6 474~3 474h2 PCP~T ..... ~TT-'-- .... % ~',/', :~ - ........ ;;;';~-~ '- o ' 33.11 ARCO AR::~ A. H A H ~o Pm so Lb) pm SoSEE,~EE~ST~ 3m-H-m6 -~ ~o Pm BP. ~ BP BP BP A H A H ~ H A H B P B P A~O ARCO ~ , , ~- AERO ~ H .ED~[, lie pi So A B ~o P~ Am H Am. H PUT~S~ H ~ BP ~BP A H A H A H A H ..... L._~ ~RCO 47455 47477 28290 ~T4~ ....... ~ 28'314 ~T; ...... pr~T~ ........... ~¢~1 ..... P ~:4 ~2 28346 28341 47414 47515 18 ~0=15 ~R 19' lO'lO 0 0 LAKE ST I .... .... ARCO ARC~ U~ PI Co Sun CmtyS Am. H U~ P[ Am H AmH H MO PI ~ -I~ ~P BP A ~ A ~ A. H U A UB ...... ~ .... Hov;) tm p ~ Aim). H ARCO ARCO Soc. Co SHn C~Ny S Co Sun Lily S Chamll~on, Am H Am H Soc BP FAo ~I. ' BP BP UP ~ P A U PiA Penn Penn ~E~m s~ ............... ~ ........................... : .................................... · ....................................... 0 ,. KA~LER S1. "m ............................ Am H U P A Chanh),on ChHmllpmorl ARCO ARCO ARCO ~lo Pm &to P, Ch,H~p~on Penn U P A ~o P' Ran~,~; ........... . ...... , ; A~O ARCO ARCO Shotm)~ye~ ARCO ARCO Ho PI W BumH~t W S H;~)~h;~lm ChHmH~or) Champmorm Lio P' Chn,q]:~mz Shotmeye~ ~o Pm Tex Shell . . 'ION rl2N rlIN TION AREA A C t '~ OGCCC NUMB£n T9N SCALE MILES BP BP ALASKA ltiC ARCO ATLANTIC RICHFIELD A H ARCO HUI~BL[ Ch,imp,on Co Sun City RCOIII 4ENTAL OIL SUNOIL · OIl ES SE'RV CE Ha~, HA~LLTOI~ el al ~o PI HOB)L PHILLIPS )40P; So t40BI L PHILLIPS SOCAL So STAIIDARD OIL OF CALIFORIIIA Tez TEXACO O P k UUION PAN AMER ICkfl ~erl Am GERB AL A~ERIO~I Bo So #OBIL SOCAL PENN -- PENNZOIL BP ARCO --BP ALASKA ARCO P.R.-B.P. PUT RIVER WELL S.D.--B.P. SAG DELTA O-WELL WITH OIL PRUDHOE LISBURNE POOL BAY COVERING' EXHIBIT U' EXHIBIT 'K' ALASKA-NORTH SLOPE PRUDHOE BAY AREA , '~ ___~ .... 3 ~"' " ~ ~ ._ ~ ~ _~ ~ : , _ .......... ~ ...............~ ~ 4 ' 9 4 4 , 4 4 , I , ~ ~ , .,~.~ :~...~ ~ ~:~: [ .,,..'. :~ ~ , 7 7 ;-;4 4 4 4 4," I I , ;~06:~8 ~-T~'¢ ....... /-'-Z~ ......... ,~/:~ ..... 7~ 2',~¢ .... · ' &~ .... - ............ . ......................... ARCO klo So A H A H : ~ p~ , I m 47587 4~503 ............... ARC0 So ~.- o PI S~ BP BP BP 9P ', ~ H A H A H A H A mm ' ~ A H H :Q I1 I ~ B P ~ P ~ p ~ P A M A H ~ A H a H B P [~ P A R C O r ~ ~A(, : 7 8 4 7~' 3 3 4 I I 4 4 4 4 4 2 II , I 5 3 ~ 7 3 3 7 I 2~ I I 4 4 4 II :;11 14 28348 47633 ' 3 9 I 7 I I m I II II 14 HEMI ST ....... . ~ 0 P; Am H ARCO ARCO IRCO ~II S4~' C_,I~.~ .S~ _ . _. Pemlr~ C(] SHr/ Cm~y S Mo pi Ir M R.iir] U P A U P AIl P ~ U P I U P.A U P I U P l . ~ ~ o ] KAOL[R m & m / ARCO ~ J ARCO ~,h, P~ ~o P m~ ...... Ch~:'~D,oH P~,H U P A ~h~ Pm ........................ H u P A NUMBER TISN 13N 4 5 TI2 12N 8 9 TIIN FIIN TION TION <~-DRY HOLE T9N TCjN W h~ W W ~ ~ ~ SCALE MILES BP ALASKA INC. ATLANTIC RICHFIELD AMERADA HESS et. al. ARCO HUMBLE CONTINENTAL OIL, SUN OIL, CITIES SERVICE HAMILTON el' al. MOBIL PHILLIPS MOBIL PHILLIPS SOCAL STANDARD OIL OF CALIF. IO TEXACO II UNION PAN AMERICAN 12 GENERAL AMERICAN 15 MOBIL SOCAL . , 14" PENNZOIL 15 BP ALASKA ARCO (~-WELL WITH OIL OIL IN KUPARUK RIVER SANDS OIL IN PRUDHOE BAY SANDS ~-- Oil IN LISBURNE AREA OF ., PRUDHOE BAY LIII mil i II FIELD PHILLIPS PETROLEUM COMPANY DENVER. COLORADO 80202 12:~O SECURITY LIFE BUILDING EXPLORATION AND PRODUCTION DEPARTMENT WESTERN REGION November 12, 1969 Re: Unitization of Prudhoe Bay Field Area Atlantic Richfield Company P.' O. Box 2819 Dallas, Texas 75221 BP Oil Corporation 620 Fifth Avenue New York, New York 10020 Humble Oil & Refining Company P. O. Box 2180 Houston, Texas Gentlemen: We have.received your letter of OCtober 22, 1969, inviting Phillips Petroleum Company to join in plans for cooperative development of the Prudhoe Bay field in Alaska. Such letter attached an agreement of August 6, 1969, among your three companies setting forth in broad terms certain principles which ~you.believe should be included in the proposed Unit Agreement and Unit Operating Agreement. Phillips Petroleum Company hereby accepts the'~nvitation to enter into negotiations looking toward unit operations for the Prudhoe Bay field area. We stand ready to nominate immediately 'qualified personnel of our company to serve on the various committees which may be appointed to work on the negotiation and drafting of the appropriate contractual documents. Inasmuch as the subject of plans for unitization is included in the topics to be examined at the hearing called by the Department of Natural Resources of the state of Alaska ir~ Anchorage on 'November 13, we are sending a copy of this letter to Mr. Thomas R. Marshall, Jr., Executive Secretary, Alaska 0i2 and Gas Conservation Committee, for inclusion in the record of suc|~ hearing as evidence of Phillips Petroleum Company's intent to participate in plans for cooperative development.. · Atlantic Richfield Company BP Oil Corporation Humble Oil & Refining Company November 12,~ 1969 ~ Page 2 · Please be assured that we firmly believe cooperative development of the Prudhoe Bay field under appropriate unitization documents to be in the best interests of all owners of leasehold interests in the area, the ~State of Alaska, and the public in general. Yours very truly, PHILLIPS PETROLEUM COMPANY C. W. Corbett, Manager Western Region CWC: TMB: lj cc Mr. Thomas R. Marshall, Jr. 0~JECTI,,,,o AT TiilS TIF'IE BY reTA!"D!C,P'.,i) 0IL Cn:PA?,,IY OF CALIFORtlIA: RECOMMENDED PRtJDtiOE :AY FIELD RULES _l_-C, 2_, AND !1 AS PROPOSED, RULE 1-C - DEFINITIO.~.I OF POOLS THE PRUDH©E BAY KUPARUK RIVER POOL REFERS TO AN INTERVAL WITHIN THE CRETACEOUS OVERLYING THE.PRUDHOE BAY SAND POOL, IT HAS BEEN DEFINED AS T:-iE ACCUMULATION OF OIL AND/OR GAS COMMON TO AND WHICH CORRELATES WITH THE ACCUMULATION FOUND IN t"!OBIL - PHILLIPS i;ORTH. KUPARUK STATE #]. WELL BETWEEN Tile DEPTHS OF 6765 FEET AND 7060 FEET, THIS INTERVAL IS TOO LIMITED FOR THE CRETACEOUS AND SitOULD BE EXPANDED TO INCLUDE 62'65 FEET TO 7765 FEET ~N NOBEL - PHILLIPS NORTH KUPARUK STATE #]. WELL, RULE 2- SPACI_~iG DENsIT.Z KUPARUK RIVER POOL AS WE HAVE DEFI~,I._D"E IT ABOVE SHOULD NOT BE INCLUDED IN THE PROPOSED G/,t0 ACRE SPACING PER POOL, THE KUPARUK RIVER POOL SHOULD HAVE A WELL DENSITY LIi'.IITED TO NORMAL STATE OF ALASKA SPACING OF NOT LESS TITAN 1G0 ACRES PER WELL AT THIS TIME, _RULE 11 - :XTEHSIOH'OF SPECIAL FIELD RULES 'TO 0TIiER POOLS RULES GOVERNING THE PRUDHOE BAY SAND POOL, PRUDHOE :AY LISBURNE POOL AND KUPARUK RIVER POOL SHOULD NOT APPLY TO OTHER POOLS YET TO BE D'ISCOVERED WITHOUT THE BENEFIT OF A HEARING, t.;. C. 8O~ILEALJ '.rt~ "bec I4r. D. O. Couvil!on Mr. A. V. ~$artlni NOT I CE STATE OF ALASKA DEPARTMENT OF NATURAL RESOURCES DIVISION OF OIL AND GAS Alaska Oil and Gas Conservation Committee Conservation File No. 83 Re: Prudhoe Bay area pool rules. Notice is hereby given that the Alaska Oil and Gas Conservation Committee hereby extends until December 15, 1969, the tirae period during which it will accept written statements for the record of the hearing held on November 13 to consider proper pool rules for the Prudhoe Bay field. Requests have been received for additional time to complete and deliver statements. Thomas R. Marshall, Jr. Executive Secretary Alaska Oil and Gas Conservat i on Comm i ttee 3001 Porcupine Drive Anchorage, Alaska 99504 Publish October 29, 1969 AFFIDAVIT OF PUBLICATION STATE OF ALASKA, ) THIRD JUDICIAL DISTRICT, ) ss. being first duly sworn on oath deposes and says that ...... ~i.[.~... is the .... ]].?..~.~...~.~..G.~.~ of the Anchorage News, a daily new~ paper. That said newspaper has been approved as a legal news- paper by the Third Judicial CouP, Anchorage, Alaska, and it is now and has been published in the English language continually as a daily newspaper in Anchorage, Alaska, and it is now and during all of said time was printed in an office maintained at the aforesaid place of publication of said news- paper. That the annexed is a true copy of a .~.~?.~...]:~P.J~;~.9.~.. 21 as it was published in regular issues (and not in supplemehtal form) of said newspaper for period of ..... ?~. ...... inse~ions, commencing on the ..... .~....d~y of ....~C;~Q'~ .... ,'1~ ...~[[~ and ending on the ..........~. ...... day of both dates inclusive, and that such newspaper was regularly distributed to its subscribers dur- ing all of sa,id period. That the full amount of the ~ee charged for the ~oregoing publication is the sum of $ 14.00 which amoun[ has been paid in full at the rate of 25¢ per line; Mini- mum charge. $7.50. Sub;~[~ed ~ sworn to before this me .... day of .... Third Division, A~horage, Alaska .... ,,..'.7/ NOTICE OF PUBLIC. I:IEARING STATE OF ALASliA ~ DEPARTMENT OF NATURAL RESOURCES DIV1S]ON OF OIL AND GAS Alaska Oil and Gas Conservation Committee Conservation File No. 83 itc: The motion of the Alaska Oil and Gas Conservation C~mit- tee to hold'a Rublic hearing to hear test~ony ~ determine the Proper pooi rules for the Prud- ~ hoe Bay ~eld. Notice is hereby '~ven %hat ~aska Oil and G~ Conservation Committee will hold a public hear- ~g~ p~suant ~ Title 11,~ .Alaska , ~ .~ .~ . ~. , A~ nistraflve' 'Code, Section 2004, on NovemDer 13 at ~:~.0 a.m. in the S$~ey L~iure~e A~itorium,' 'Sixth Avenue '~d "~" 'Street, 'Anchorage, laska, at which t~e affected and ~terested par~es w~l 'be' heard. The 'Committee Will Seek leStim0ny on any.. matter relevant to the P[O~er.~ .~eveloPm'ent..: and operation 0f the p~[ or pools~ ~cluding, bui n~ ~ited to, the :ioll0wtng: · 1. Area to ~e affected by the order :. ' ~ ~; Vertical definition"of th6 pool 0r pools ~ 3, Well..spacing including Iootages .io lease ~d property lines and acreage spac~g 4. Cas~g ,and cementing require- ments S. Bottom. bole pressure survey requirements 6. Gas-off ra~o test requirements 7.~in/stra~ve approves, if any 8. Pl~s io~ ~dJsposition oI pro- duced gas~ 9.Plans far unitization Thomas R. Marshal, Executive '~ Secretary Alaska Oil and Gas Conservation Committee 3001 Porcupine Drive Anchorage, Alaska 99504 Publish: October 7. 1969. Leg~ Notice ~o. 2135. ~~cHo~,~°J~°t~ 4N~ o4s NOTI'CE OF PUBLIC HEARING STATE OF ALASKA DEPARTMENT OF NATURAL RESOURCES DIVISION OF OIL AND GAS Alaska Oil and Gas Conservation Committee Conservation File No. 83 Re: The motion of the Alaska Oil and Gas Conservation Committee to hold a public hearing to hear testimony to determine the proper pool rules for the Prudhoe Bay Field. Notice is hereby given that the Alaska Oil and Gas Conservation Committee will hold a public hearing pursuant to Title 11, Alaska Administrative Code, Section 2004, on November 13 at 9:00 a.m. in the Sidney Laurence Auditorium, Sixth Avenue and "F" Street, Anchorage, Alaska, at which time affected and interested parties will be heard. The Committee will seek testimony on any matter relevant to the proper development and operation of the pool or pools including, but not limited to, the following: 1. Area to be affected by the order 2. Vertical definition of the pool or pools 3. Well spacing including footages to lease and property lines and acreage spacing 4. Casing and cementing requirements 5. Bottom hole pressure survey requiremen.ts 6. Gas-oil ratio test requirements 7. Administrative approvals, if any 8. Plans for disposition of produced gas 9. Plans for unitization Publish October 7, 1969 Thomas R. Marshall, Jr. Executive Secretary Alaska Oil and Gas Conservation Committee 3001 Porcupine Drive Anchorage, Alaska 99504 COMMITTEE EXHIBIT NUMBER LIST Conversation Order No. 83 No. Assigned by Committee 83 - 1 83 ' 2 83 - 3 83 - 4 :::, 83 - 5 ~ 83 6 .... :.,~ 83 - 8 83 - 9 83 - 10 .:,:,,' 83' 11 83- 12 83- 13 83 - 14 Date Received November 19 November 24 November 26 November 28 November 28 November 28 November 28 November 28 December 1 December 1 December 1 December 1 December 15 December 15 December 15 Submitting Pa. rty Concrete Research and Technology Gerald Ganopo le Humble Oil Company Pan American Petroleum Corporation Standard Oil Company of California Hamilton Brothers Oil Company Louisiana Land and Exploration Company Atlantic Richfield Company Marathon Oil Company Highland Resources, Inc. Mobil Oil Corporation Pennzoil United, Inco Union Oil Company of California Amerada Hess Corporation BP Oil Corporation WEST SURFACE EAST SAGAVA N IR KTO K PRUDHOE bAY GROUP ~-~~.....~...... SCHRADER BLUFF SEABEE// TOROK -'-" KUPARUK RIVER ~ KINGAK ~ .... ---"~-'- ..----'"'~ ....... --------~~ OXYTOMA .................. -~-'""' OI_L. j...- -'---"~----- SHUBLIK .-"'" .~"'"'-- O I L SADLEROCHIT SAND J .._~--'" WAT____R '-~' -' "" SA, DLE'ROC HiT SHALE ,~.~ WATER LISBURNE LIMESTONE SAND/SHALE "ARGILLITES" Presented to' Oil and Gas Conservation Committee :Presented by' B.P. Alaska Inc. Conservation File: #83 Dated' November 13, 1969 SCHEMATIC CROSS-SECTION J OF PRUDHOE BAY FIELD T ~3N TI2N ALASKA-NORTH SLOPE PRUDHOE BAY AREA w ~u w m "' w w ~_ ~_ ~ -- BP ARCO Mo So ~ So A H h H A H [ ~o P~ Ph' P' .... ~'}'7T ...... ......... ARCO No So ~ H A H A H ~ i BP ) UP , BP H ............................................................. ' ................. 28346 41474 4151~ b 0 , ~R ....... ~ H LAKE S~I ARGO ARCO klo. PI CO SHH ~tyS. AH,. H tAD P~ 'BP MD 91, BP BP BP m ~ P A U P A P~, ~DD" -- u3 ~ ~,~. H. ~CO ARCO So( ~o 21in ~Lty ~ Co S¢11 Cl1y ~ Challlr)lofl Alii H. ~m H ~OL, I 0 ARCO ARCO AR'~O Co St, n C ,v ............................................................. - .............................. .. ................... KADLER Champ~¢', ARCO AR~O ARCO . , ' , , , lJ A D L~ OOGOO j NUMBER BP BP ALkS~A IliC ARCO AILAIITI C RICer IELO A H JiRCO HUNBLE kr~ t~ ANERAD~ MESS el Chamu~ Gn Co S~:,~ C~t~ S CORTIIIEIf~L OIL SUtO L C)ll[S SE~V H~m MAN] LTOli e~ ~o P3 NOB)L PHILLIPS ~o D So MOB . ~HILLIPS SOCA. SO SIAIJD~RD 0 . OF CALIFORNIA lex TEXACO ucDp A U ON PAI~ AMER ILAR m~l?N.... GEIIB AL ~o Sc MOB L SOCAL PENN - PENNZOIL BP ARCO BP ALASKA ARCO P.R.-B.P. PUT RIVER WELL S.D.--B.P. SAG DELTA ~-WELL WITH OIL TION AREA COVERING PR UDHOE BAY mi m - LISBURNE POOL I Ill Im m w LI.J IJ.J · I,t.J SCALE m ~ ~ ~:...:_~;::..~':.:.=: ::,:.~:,:.~' - ~~~:.:;:~:::.~.:::.__::__7:.::Lde=_..__~.?_~._~._~_~.r:.___%~_::.z..::::: ~ ~¢' ~ M LES AS ...... Z_bI_E.~ TYPE BBUD HO E 84OO 8500 8600 PENETRATED IN ARCO HUM -.. ',.' t 8700 I I ' i /,./ LOG OF BAY SAND_. POQL LES PRUDHOE BAY STATE :1=1:: I LEGEND' PREDOMINANT LITHOLOGIES ~ SANDSTONE 1~;~2~' S HA L E ~ SHALE-SANDSTONE I~ BAY POOL USA Technical Report 1.99 GEOLOGY OF THE CRREL PERMAFROST FAIRBANKS, TUNNEL ALASKA by Paul V. Sellmann JULY 1,967 U.S. ARMY MATERIEL COMMAND COLD REGIONS RESEARCH & ENGINEERING LABORATORY HANOVER, NEW HAMPSHIRE DA Task1VO25001A13001 Distribution of this document is.unlimited PREFACE This geological study was undertaken to provide the pertinent region- al and historical geology of the tunnel site and immediate surroundings, as well as data on the index properties of the material through which the tunnel passes. It is a supplemental study to USA CRREL Project 6. 1, Rapid Tunneling Techniques in Frozen Ground, which was responsible for excavating the tunnel in permafrost near Fairbanks, Alaska. The planning, objectives, and construction phases of the tunneling operation are reported on by F. Russell (1963), J.E. McCoy (1964), and G. Fi. Swinzow (in preparation). The author acknowledges the support provided by the USA CRREL Alaska Field Station and wishes to thank Mr. Otto Engelberth for his en- thusiasm and highly capable assistance during all phases of the study. Thanks are extended to Dr. J. Brown, Dr. T.L. P~w~, Mr. L. S. Ding- man and Dr. G. E. H. Ballard for reviewing and providing constructive comments and suggestions on the manuscript and work in general. This report was prepared by Mr. Paul V. S'ellmann, Geologist, of the Applied Research Branch (Mr. A. F. Wuori, Chief), Experimental Engineering Division (Mr. K. A. Linell, Chief), USA CRREL. USA CRREL is an Army Materiel Command laboratory. iii CONTENTS Preface Summary Introduction General geology Permafrost conditions Tunnel geology Bedrock Gravels Silts Ground ice Chemical gradient Stratigraphy ............... C oncluding statements Literature cited Page iv 1 1 3 4 4 6 6 1Z 14 16 19 2.0 Figure 1. Z. ILLUS T RATIONS Topographic map of tunnel site Diagrammatic cross section of creek valley of central Alaska 3. Tunnel site secticfn 4. Depth to bedrock .along entire seismic line 5. Bands and lenses of rock'fragments in the silts of the tun- nel section ...................................... ? 6. Section at Sra. 00+96 8 7. Mechanical analysis of tunnel material and hilltop silt sec- tions ---. ........................................ 9 8. Idealized sketch of tunnel section 9 9. Diagrammatic section of vertical ventilation shaft ....... 10 10. Lenses of segregation ice 13 11. Flat-topped ice wedge at sra. 3+55 13 12.. Chemical concentration with depth in meq/1 15 13. Ice wedge distribution and relative position of radiocarbon dates from the tunnel section 15 TABLES Table I. Physical properties of material II. Samples dated 11 17 iv SUMMARY The age and sedimentary environment of a perennially frozen Quaternary silt section in the USA CRREL permafrost tunnel near Fair- banks, Alaska, were established by radiocarbon dating and stratigraphy, and substantiated by a study of the chemical gradient and massive ground ice structures. Data on the index properties and seismic velocities of material through which the tunnel passes were also gathered. The section proved to be Late Wisconsin in age, with. the maximum determined date of 33,700 (+2500, -1000) years. Ice wedges occur throughout the section. The large forms, exceeding a meter in width, are found only below 12 meters. Scattered vertical distribution, truncated flat tops, and second cycle growth of wedges suggest changing depositional and/or climatic conditions during their formation. Two distinct breaks, "unconformities," are noted in the section. The lower break at a depth of approximately 12 meters is indicated by: radio- carbon dates jumping from approximately 14,000 to 30,000.years; total ion concentration showing in excess of a five-fold increase;'and sudden occurrence of.large wedge Structures,' some'of which exhibit second cycle growth. The upper break at the depth of 3 meters is suggested by radio- carbon dates and a small truncated ice wedge and may indicate a warming period during late Wisconsin time. Lower total ion Concentrations and. smaller ice wedges in the 13-meter section suggest that during or shortly after deposition the unit was subjected to warmer climatic influences, and possibly deeper thaw, than accompanied, fo~'mation of the lower unit. GEOLOGY OF THE USA CRREL PERMAFROST TUNNEL FAIRBANKS, ALASKA by Paul V. Sellmann INTRODUCTION The USA CRREL tunnel is at Fox, Alaska, in the Glenn Creek Valley, ap- proximately 10 miles north of Fairbanks on the Steese Highway (64°57'N, 147° 37'W). It was excavated in perennially frozen silts of Pleistocene age. These silts have been of scientific and economic interest in the Fairbanks area since the turn of the century because of the need to economically remove thick sec- tions of the material to expose the underlying gold-bearing gravels. The frozen sediments also preserved large floral and faunal assemblages, thereby retain- ing a record of plant and animal life and of the changing environmental conditions during late Quaternary time. Physiographically the tunnel area is near the southern limit of the Yukon- Tanana Upland of interior Alaska. The upland consists primarily of rolling hills separated by broad alluvial- and colluvial-filled valleys. Spruce, aspen, birch and willow are the common trees. The ground cover is mainly mosses, sedges, Labrador tea, dwarf willow and various berry-producing bushes and dwarf-tree forms. The tunnel portal was "excavated into a near-vertical silt escarpment formed by a placer mining operat!oa (Fig. 1). USA CRREL Project 6.1 personnel con- structed the 360-ft tunnel during the winters of 1963-64, 1964-65 and 1965-66 using an Alkirk mining machine and a modified blasting technique. Sections in the blasted area are irregular and fractured, in contrast to the milled and nearly polished machine-made exposures. A vertical shaft 45 ft deep and 4 ft in diameter was augered'in 1966 for ventilation. The excavation provides unique exposures of the frozen sediments and an opportunity to study in detail the local stratigraphy and complex ground ice structures. Information on the index properties of the material through which the tunnel and vertical ventilation shaft pass was obtained from analysis of more than 60 samples. The late Quaternary history was interpreted with the aid of radiocarbon dates, stratigraphy, chemical profiles, and a study of the ground ice structures. GENERAL GEOLOGY The bedrock in the area consists chiefly of the Birch Creek schist of Pre- cambrian age which underlies most of the Yukon-Tanana Upland. It is a gray to brownish graphite-quartz-calcite schist or quartz-mica schist. Inclusions of low grade marble are found near the tunnel site. These metamorphic rocks are intruded by quartz diorites, granite, and dike rocks of Mesozoic age (Mertie, GEOLOGY OF THE USA CRREL PERMAFROST TUNNEL Figure N VENTILATION SHAFT CONTOUR ZNTERVAL: 4 FT IOO o IOO SCALE IN FEET Topographic map of tunnel site with superimposed tunnel section. The bedrock units are mantled by unconsolidated, largely ice-cemented silts and gravels of Pleistocene age. Immediately overlying the bedrock in the valleys are early Pleistocene gravel~ deposits, possibly Nebraskan and Kansan in age, which contained the placer gold deposits (P~w~ et al., 1965a) (Fig. Z). These gold-bearing gravels are capped by thick retrans~-~i-ed silt sections that are thought to range in age from Illinoian to Recent. The Illinoian deposits contain considerably less ground ice and organic material than the younger units. It is believed that ice originally in the Illinoian section melted during Sangamon interglacial time {P~wd, 195Z, 1958, 1965a). The overlying silt of Wisconsin age is characterized by large ice wedges and GEOLOGY OF THE USA CRREL PERMAFROST TUNNEL °lr ~J o ' '?'/,t I ~ ' '~ ~'i~..._ \ (Kansonp) ~:A~ 150 -- (Nebroskan.P) ~/-~' _ BEDROCK 0 200 400 600 DISTANCE IN FEET Figure ~. Diagrammatic cross section of Quatern- ary sediments in creek valley of central Alaska, showing stratigraphic position of tunnel section in relation to entire range of Pleistocene sediments (after P6w~ et al., 1965a). high organic content. Horizontal bedding and sedimentary structures are not particularly abundant in this massive, amorphous material. Convoluted and distorted gravel zones, possible bedding, and swirls of sediments constitute the most common megascopic structures. Bones of large extinct vertebrates, such as the bison and mammoth, are commonly found. The presence of fresh water pelecypods suggests that small ponds existed in the valley bottoms. The origin of these silts has been a subject of some controversy and has been discussed by Taber (1943, 1953; 1958), Black (1951) and P6w~ (1955). It is generally accepted that the .silts are eolian in origin. They can be di- vided into two groups based on their subsequent history: (1)the primary eolian silts found mantling the hilltops along the southern margin of the Yukon- Tanana Upland, and (g) the. valley bottom silts, a product of retransport of the hilltop material by slope wash, solifluction and normal fluvial activity. The source of the wind-blown silts in the Fairbanks area is the stream-trans- ported glacial material originating from the glaciers of the Alaska Range and deposited'on the broad, braided flood plain of the Tanana River. Rigorous climates during glacial times were responsible for a decrease in stream dis- charge and an increased load, forming the broad, braided, treeless flood plain, and providing large areas of fine-grained sediments for windborne trans- port. The tan to buff-colored sections of silt are well-sorted and structure- less (Taber, 1953; P~w~, 1955). These same eolian processes are taking place today but on a smaller scale. Details concerning the mineralogy have been reported by P~w'e (1955). PERMAFROST CONDITIONS The tunnel at Fox is in the center of the zone of discontinuous perennially' frozen ground (permafrost). South-facing Slopes and those parts of the valley bottoms containing coarse-grained sediment with correspondingly high perme- ability and well-developed internal drainage are usually free of perennially · frozen ground. The maximum thickness of the perennia.lly frozen ground in the 4 GEOLOGY OF THE USA CRREL PERMAFROST TUNNEL Fairbanks area has been reported to be greater than 265 ft (Pdw6, 1958).. The thickness of the active layer in the undisturbed, moss-covered wooded areas of the Glenn Creek Valley about g00 yards southeast of the tunnel site is ap- proximately 28 in. (Dingman, 1906). The differences in the ground ice volume incorporated in the sediment in the vertical shaft indicate that maximum depth of the active layer in recent times is 30 in. The active layer is relatively free of visible ice lenses and the moisture content is generally much lower than in any other parts of the section. The ground temperatures adjacent to the tunnel, measured along several profiles during and after tunnel construction, ranged from a minimum of g8 to a maximum of 31F (Swinzow, personal communication, 1905). Air circula- tion through the tunnel from January through March 1900, caused by natural convection induced by the newly constructed ventilation shaft, allowed ground temperatures of the sediments to be lowered as much as g0 and 14F, g ft and 8 ft from the tunnel wall, respectively, in the vicinity of station 1+50 * McAner,ey, personal communication, 1966). Since the thickness of the frozen zone is extremely variable in areas of discontinuous permafrost, thawed zones within or below the frozen sediment could create severe construction problems, particularly if the tunnel were to intersect an unfrozen zone acting as an aquifer. The tunnel may also upset the thermal regime by warming the frozen ground adjacent to it, causing back-thaw which may result in wall failure or inflow of water. The high prob- ability of the existence of thawed zones is indicated by cases in Siberia (Tsy- tovich and Sumgin, 1937) and the Fairbanks area (P6w6, 1958). The problem of encountering thawed zones in the present excavation would become more critical if the tunnel were to be advanced toward the ridge to the east, since permafrost commonly grades out locally as the ridge tops are approached. TUNNEL GEOLOGY Bedrock Bore h'ole data. To determine the thickness of the ice indurated sediments over bedrock, positive bore hole information for the sediments in the immedi- ate vicinity of the tunnel was obtained from the records of the United States Smelting, Mining and Refining Co. The records indicate that depth to bedrock along the tunnel section is around 60 ft (Fig. 3). These data were used as con- trol for refraction seismic measurements made along the tunnel centerline to extend the profile well up onto the ridge to the east. Seismic study. A ZS00-ft line was run from the portal uphill along the proposed tunnel centerline. Ten overlapping seismic spreads with various phone spacings were placed along the line. This provided reasonable data for the projection of seven vertical profiles. A plot of the seismic data is shown in Figure 4. The seismic information was gathered with a small portable l?--channel recording seismograph. The location and intensity of the energy source varied depending on the attenuation of the energy along any one line. The maximum charge used was 1/Z pound of dynamite. The organic mat was stripped to'the base of the thaw layer and the geophones were placed directly in the frozen material. The charges were placed in holes drilled at least Z ft into the frozen ground. * Tunnel station designations are in feet from the portal (1,50- 150 ft). ~_ 40 mz 20 0- GEOLOGY OF THE USA CRREL PERMAFROST TUNNEL 4O Figure 3. .... USSMR · $1cr 'l CO. BORE HOLES-- VENTILATION SHAFT SEISMIC I PROFILE °eo A oo 0+00 I+00 2+00 :~+00 STATIONS IN FEET Tunnel site section. Depth to gravel and bedrock based on USSMR Co. bore hole records. The records produced were of excellent quality, although velocities in the various media were quite similar, and it proved somewhat difficult to determine the exact' position of subtle velocity breaks. The velocities for any one layer were 'determined from separate lines. Velocities within the upper medium varied from 7700 to 11,000 fl/sec. These variations are probably caused by the difficulty in constructing the precise slope for the time-distance data. The mean velocity for the upper unit (the frozen silts) is 9400 fl/sec. The' calculated values for the depth to bedrock from the seismic data agreed well with the depth obserged at the logged drill holes. The profile data for the bedrock-colluvium interface are reasonable, with the exception of two question- able points (Fig. 4). Four of the profiles suggest alow velocity medium in the upperpartofthesiltunit. This zoneis restricted to the upper 9-15 fl, and has average velocities of 6Z00 fl/sec. These low velocities may reflect a decrease in the organic content with depth or a temperature controlled factor. Informa- tion from the vertical shaft suggests that the moisture content is slightly lower in the upper zone, which may also account for the lower velocities. The final break in all records is assumed to indicate the depth to bedrock. The velocities in the lower medium' average around 14, 500 fl/sec. The break probably represents the bedrock-c011uvium interface rather than the silt-gravel interface. This is based on the assumption that the gravel pinches out toward the valley side at.approximately 800 fl.from the portal along the proposed tun- nel centerline, and on .the configuration 6f the bedroc~k profile. · Even though the velocities in the frozen silt seem somewhat low, compari- son of the seismic data with the test borings indicates that they are in reasonable agreement. This is also substantiated by the reasonable configurkti°n of the measured bedrock surface. The break between the silt or gravel and the bedrock is probably somewhat .transitional. Small fragments of bedrock become more abundant toward the silt/gravel-bedrock interface. The bedrock, particularly the schistose r'ock, is often deeply weathered and frost-shattered as shown in other exposures in the Fairbamks area. 6 GEOLOGY OF THE USA CRREL PERMAFROST TUNNEL ~20 ~o 80 O~ =z 40 ~,~ TUNNEL . ~,u,~ ~,~.~.~~'~ I-0 ,-~.ssumed · CO ~o ~ L. ~ . ~ ~ ~ ~ ~ ~ ~ ~ 16~+00 ~ ~ ~ 0+00 4 *00 8+00 12+00 20+00 Z4 +00 STATIONS IN FEET Figure 4. Depth Lo bedrock a[on~ entire seismic line. Dots indicate pro- jected depth to bedrock from seismic information, x indicates a break [n ~he upper par~ of the s[~ section [n some of the prorates. Gravels The average thickness of the gold bearing gravel overlying the bedrock in. the vicinity of the tunnel is around 13 ft (J..'D. Crawford, USSMR Co., 1965). These relatively old gravels are not exposed in the tunnel, except possibly in a reworked form near the portal. The several gravel-rich zones along the tunnel section appear to be of two general types, based on particle size and age of the material. The first, near the portal bet,,veen sta. 0+00 and l+00, contains fresh angular rock fragments several inches in size, pos- sibly deposited by streams and modified by solifluction processes. In the upper part of this gravel section the material commonly occurs in bands, lenses and pods {Fig. 5}. These may have been mantled with Illinoian silts, as observed in several other Pleistocene sections in the Fairbanks area. The silts, if present, were later removed, by erosion, down to the gravel during Sangamon (intergla- cial} time, for the gravel is now overlain by silt of Wisconsin age, with a grada- tional contact from which organic material was dated at around 14~ 000 years. The second general type occurs between sra. Z+50 and 3+60. In the upper part of the tunnel exposures this zone contains small angular rock fragments, and is largely made up of material in the coarse sand to small gravel range with little material exceeding Z in. in size. Small sedimentary structures retained in these gravels, such as orientation of the long axes of the particles and thin'in- terbedded bands of silt, suggest stream deposition of the material. Areas rich in fibrous organic material are commonly found adjacent to these zones (Fig. 6). This section was incorporated in sediments that dated around 30,000years, suggesting a mid- to late-Wisconsin age. Silts Of the material that constitutes the late Pleistocene sediments in the area,. silt is by far the dominant type. The silt sections are as much as 55 ft thick. Even though the silt of the Fairbanks area has been reported as being Illinoian to Recent in age, no evidence of the Illinoian section is found along the 35-ft escarpment at the tunnel site, or in the available tunnel exposures. Several mechanical analyses were run on the tunnel and hilltop silts for a comparison of the hilltop parent material and the retransported end-product (Fig. 7). The simila/'it¥ between the valley silts and the hilltop materials is GEOLOGY OF THE USA CRREL PEPdV[AFROST TUNNEL 7 a. Sra. 1+04. b. Sra. 0+32-. Here some of the axes of the rock frag- ments have a preferred orientation (imbroc,ation) which suggests stream deposition. Figure 5. Bands and lenses of rock fragments inco.rporated in the silts of the tunnel section. The abundance of the rock materialinthese sections is far greater than in the normally well-sorted sections. 8 GEOLOGY OF THE USA CRREL PERMAFROST TUNNEL Figure 6. The section at sra. 00+96 illustrates the extreme variability of the material: (A) organic mat- erial, (B)rock fragments, (C)massive ice, and (D) silt. apparent. The analysis of composite silt samples from the tunnel section in- dicated that 68% of the material falls within the silt range. This compares with 7Z% for the eolian sections on the surrounding hilltops. The sediments were describc~:l and sampled along the 360-ft tunnel (Fig. 8) as well as in the vertical shaft (Fig. 9). The frozen silt samples were cored from the exposures with a slightly modified USA CRI{EL ice auger. Tungsten carbide cutters were substituted for the conventional steel cutters and the core barrel was adapted to a hand-held, rotary percussion electric drill. This com- bination proved to be very successful, permitting thirty 1-ft long samples to be taken in a 4-hr period. Forty-six. samples were collected along the horizontal tunnel section and Z0 additional samples were collected at 2--f~intervals in the vertical ventilation shaft that intersects the tunnel at sra. 3+ 55. These samples were processed in the laboratory to determine: '(1) bulk density, (Z) dry density, (3) moisture content (105C), (4) organic content, and (5) some of the grain specific gravities. The void ratios and ice volumes were calculated, and some of the specific gravities were interpolated from an organic content-specific gravity curve based on laboratory tests. All the above values are given in Table I. The bulk densities and dry densities of the samples from the vertical shaft were not determined directly in the laboratory but were calculated from grain specific gravities determined by the air pycnometer, and the weights of the constituents. It was assumed that the samples were saturated, and this was substantiated by work done on the tunnel section materials. Additional prop- erties of the sediments were delineated from the shaft section: (1) specific conductance of the soil water extract, and (Z) the carbon-nitrogen ratios of some of the samples. GEOLOGY OF THE USA CRREL PERMAFROST TUNNEL u $ STr, S~E ;E $~ZE ~0 40 NO 200 I \A I i i i ii~ i i i i f 8O 60 20 0 I0 0 0.01 GRAIN SIZE IN MILLIMETERS 0 001 SAND Jj J SILT OR CLAY Med J F,ne Figure 7. Mechanical analysis of tunnel material and,hilltop silt sections. A -Hill- top slit'(loess) collected from 10-ft section on Birch Hill (Fort Wainwright). B - Hill- top silt (loess) colIected from 15-ft expos- ure near University of Alaska experimental station. C - Composite sample from en- tire tunnel section. 105 ~oo IiO SILTI ~-'*'°- ~-' "/'"" ' I' ., i} , ¥' : 105 CARBON DATED I 9~ I I I I I I I ............. I" ' /9~ 0+00 0+~ 0+~ 0+~ 0+~ I+00 1+20 1+40 I+~ STATIONS IN FEET .... ~, , .... ,,;,,"',;: ......... .... , .... :, . , " '' f I I I t I I I I ~95 I+eO 1+80 2+00 2+20 2+40 2+60 2+80 3+00 3+20 3+40 3+60 STATIONS IN FEET Figure 8. Idealized sketch of tunnel section showing distribution of major tunnel constitu- ents; silts, gravel, orgahic material and ice. Dots indicate sample locations. 1 0 GEOLOGY OF THE USA CRREL PERMAFROST TUNNEL 10 n~ 20 0 ~- 25 ~ ~0 35 4O Reddish brown sandy silt w/zones rich in organic material. Little visible ice. Mottled gray to red oxidized zones. Active layer {low moisture conlent) from 0' to g. 3' Fhin band of dense, compacl, 11. brown to yellow fibrous organic material at 4. 8'. Grades from reddish brown to brownish gra.v sills. Peat zone. Fibrous woody organic material. Gray silts. Very thin lenses. Fransition to more organic-rich silts. Small wedge. High fibrous organic content. Gray silt. Numerous large logs. Very fibrous organic gray silt. No massive ice (small veinlets). Gray silts. Predominantly woody organic ~aterial. Grayish brown organic silt. Predominantly rootlets. No woody peal. t-lair ice (segregation ice) from gS' to g~)' Brownish gray silt. Large veinlets. Woody organic 'zones fron~ ).t' to ~5' Very fibrous organic matt'rial. Occurs in peaty masses. Small twigs incorporated in silt. High organic content. Sandy silt. P'oliated ice Figure 9. Samples taken at Z-ft intervals. Clear ice (~ Samples dated I)y ('-1.I.. Diagrammatic section of vertical ventilation shaft at sra. 3+55. All silts are amorphous. QEOLOGY OF THE USA CRREL PERMAFROST TUNNEL 11 TABLE I. PHYSICAL PROPERTIES OF MATER/AL. Sample no. Bulk density, ¥ Dry density, rD Moisture Void Grain Vol. Vol. content ratio spec. org. ice ( lb/fi~) (~/cms) (lb/ft3) (g/cra3) w (%) e gr. (%) 0+40{i) 96.8 0+40(z) 90.5 0+40(3) 98.0 0+40(4) 95.5 0+40(5) 99.3 0+70(1) 91.2- 3+80(1) 94.3 0+90(1) 88.0 1+oo(1) lOO. 5 1+1o(1) 80.5 I+ZO(1) 103.6 1+30(1) 83.7 1+30(2.) 93, 6 1+ 30}31 104.3 1+30 4 91.8 1+30(5) 86.8 1+30(6) 91.8 1+30(7) 95.5 1+80(1) 80, 5 z+zo(1} - Z+30(1 3Z. 4 Z,40(1 96. 1 Z+40(Z) 93. 6 2+40(3) 91.8 Z+40(4) 87.4 2+40(5) 93.6 2+40(6) 94. 9 Z+40(7) I 00. 5 Z+40(8) i OZ. 3 Z+40(9) 93. 0 2+50(1) 99.9 Z+60(1) 103.6 24 7011) 100. 0 2+80~1) 8Z,4 2+90(1) 88.7 3+ )0(1) 92.4 3+10(1) 89.9 3+zo(1) 85.5 3+4o(1) 81,z 3+40(z) 90.5 3+40(3) 88.7 3+40(4) 89.3 3+40(5) 89. 3 3+40(6) 88. 7 3+40(7) 83.7 3+40(8) 79. 3 1.55 60.0 1.45 49.9 1.57 61.8 1.53 58.7 1.59 63.7 1.46 51.8 1.51 56.8 1.41 46.8 1.61 66.8 1.Z9 35.9 1.66 71.8 1.34 40.0 1.50 58.8 1.67 72.4 1.47 53. 1 1.39 45. 0 1.47 53. 7 1.53 59.3 1.29 36.2 . 1.32 39.3 1.54 60.0 1.50 56.8 1.47 54.3 1.40 46.8 1 50 56. Z 1 52 60.6 1 61 66.8 1 64 63, 7 I 49 55.6 i 60 65.6 i 66 71.z I 59 64.3 I 32 38. l I 42 48. 1 I 48 54.3 1 44 50. 6 I 37 43.7 ,1 30 36.8 1 45 50.6 1 42 48. 1 I 43 18.7 I 43 49.3 1 42 48.7 I 34 40. 6 I 27 35.0 # 2 114.9 1.84 86.8 ~ 4 89.3 1.43 50.9 ~ 6 100.5 1.61 66.6 '~ 8 108.0 1.73 77.8 ~10 97.4 1.56 6Z. 5 #lg 1,04.3 1.67 72.5 #14 84,3 1.35 41.5 #16 90.5 1.45 51.1 #18 93.6 1.50 55.9 ~Z0 100.5 1.61 66.1 #2-2 90.5 1.45 50.9 #24 80.5 1,29 35.6 ¥Z6 78.0 1.25 3Z. 8 #28 86.8 1.39 46.0 ~30 88.0 1.41 47.7 #3Z 93.0 1.49 56.2 #34 78.0 1.25 33.9 77.4 1.24 33.7 ~36 95.5 1.53 58.7 #38 86.1 1.38 45.4 #40 99.9 1.60 65.7 TUNNEL 0.96 60.9 1.78 Z. 68 Z. 7 64.1 O. 80 79. 7 Z. 33 Z. 68 Z. 7 69.9 O. 99 57.8 1.67 Z. 66 3.9 62.7 O. 94 62.4 '1.80 Z. 65 4.3 64.3 1. OZ 54.7 1.58 Z. 65 4.6 61.3 0.83 75.7 Z.18 2.64 4.1 68.6 O. 91 66.3 1.92 Z. 66 4. 1 65.8 0.75 87.9 2.55 2.66 3,1 71.8 1.07 50.7 1.47 2. 65 4.7 59.4 O. 57 126.8 3.66 2. 65 Z. 5 78. 6 1.15 44.7 1.29 2.64 5.6 56.3 0. 64 107.8 3.09 Z. 63 3.3 75.6 0.91 65.6 1.88 Z. 6Z 5.0 65.2 1.16 44.5 1.Z7 Z.63 5.9 56.1 0, 85 72.9 Z. 07 2.61 5.1 67. 5 0.7Z 91.3 2.60 2.61 4, 3 72.2 0.86 72.0 Z. 07 Z. 63 4.6 67.4 0.95 61.2 1.73 2.59 6.6 63.4 0.58 122.8 3.52 2.63 3,3 77.9 - 109.7 - _ 0,63 111,4 3.19 2.63 5.7 76.2 0.96 60.3 1.72 Z. 63 5.2 58. 1 0.91 66.1 1.88 Z. 61 5.7 60.4 0.86 70. 1 1.97 2, 57 6.8 66.3 0.75 86.5 Z. 44 2.59 5. 1 65.0 0.90 67.2 1.9! 2.. 61 5.8 60.2 O. 97 57. 1 1.52 2.45 7.4 55, 4 1.07 50, 5 1.42 Z. 59 7.3 53.8 1.10 47.9 1.38 Z.63 5.8 57.9 0.89 67.8 1.92 2.60 5.9 60.3 1. 05 52.3 1.50 2.64 5. 1 55. 1 1. 14 45.2 1.29 Z.62 6.5 56.4 I. 03 54.3 1.56 Z. 63 5.6 60.9 0.61 114.7 3.43 Z.7O 1,8 77.4 O. 77 84.0 2.41 2.63 4. I 70.7 O. 87 70.8 Z. 02 Z. 61 5. 1 66.8 0.81 77.0 2.16 Z.58 6.1 62.7 O. 70 96.8 2.77 2.62 4. 1 73. 5 O. 5'9 IZO. 7 3.50 Z. 66 Z. 2 71. 3 0.81 78.8 Z. 28 2, 65 3.6 69, 5 0.77 84.4 2.43 2.64 3.7 64.9 0.78 83. 1 2.38 Z, 64 4. Z 64. 5 O. 79 81,6 2.33 2.62 4.5 64. 1 0.78 81.4 Z.30 2.59 5.6 69.7 O. 65 104.6 Z. 95 Z. 59 4.4 68.5 O. 56 128.2 3.53 Z. 53 5.2 71.4 VERTICAL SHAFT 1.39 31.8 0.94 2.70 3.4 48.4 O. 82 74, 9 2, 00 2.45 7.4 66.7 1. 07 50.5 1.44 2.60 5.5 58.9 1.25 39.0 1.13 2.66 2.6 53.2 0.99 57. 1 1.63 Z. 61 4.3 6Z. 0 1,16 44.0 1.27 2.63 4.2 55.9 0.66 1 OZ. 1 Z. 88 Z. 57 3. Z 74. Z 0.8Z 76.8 2.19 2.61 3.2 68.7 0.89 67.6 1,95 Z. 64 6.0 66.0 1.06 52. 1 1.5Z Z. 67 3.4 60.3 0.81 77.8 Z.25 2.65 Z.9 69.2 0.57 126.3 3.71 Z. 69 1.4 78.8 0.5Z 138.8 3.91 2.58 Z. 9 79.6 0.74 88.6 2.48 2.57 4.5 71.3 0.76 84.3 2.38 2.58 70.4 0, 90 66.0 1.85 Z. 56 4.9 64. 9 0, 54 130.1 3.39 2.39 4.5 77.2. 0.54 3.30 2.32 4.5 76.7 0.94 62.4 1.79 2.. 62. 3.6 64. 1 0.7Z 89.6 Z. 46 Z. 52 4.7 71. 1 1,05 51.8 1.47 2.60 4.0 59.5 Sample No. = Position along tunnel section. Total wt. Bulk density = 3C = Total vol. Wt. solids Dry density = 3CD Total vol. Wt. HiO xl00 Moisture content = w = Wt. 'solids Void ratio = e = Vol. voids Vol. Solids vi Vol. % ice = % VI =~ x 100 Vol. % org.= % Vorg =~x 100 VTotal 12 GEOLOGY OF THE USA CRREL PER_\.fAFROST TUNNEL The material that makes up the tunnel section has unusual properties, which are determined largely by its high ice volume. The bulk density values of the material range between 78 and 115 lb/ft3 and average 9Z lb/ft3, ~.vith moisture contents between 3Z and 13% by dry weight. The dry densities ranged f~om 33 - 87 lb/ft3 with an average of 54 lb/ft~. Tests performed on silts from the Fairbanks area by the Corps of Engineers indicate that the maximum dry density as determined by the modified AASHO method is 107.4 lb/ft3 with an optimum water content of 17. 1%. The dry density for un- disturbed unfrozen samples varied from 97. 1 - 101.5 lb/ft3 with natural mois- ture contents of ZZ. 9 - Z6.9%o. The fine grained gray to gray-brown mineral material in the sections is largely silt sized, with sand to sandy silt constituting the coarsest material in the fine grained fraction. In both the tunnel and the vertical shaft distinc- tive differences in the physical appearance of the sediment can be attributed to the varying amounts of organic material and ground ice in the sediment. Fig- ure 8 shows the distribution and variability of some types of material that made up the tunnel section. The silts generally lack recognizable sedimentary structures, although upon close inspection some of the amorphous zones reveal very thin laminations. The convoluted, distorted nature of the sediments is commonly clearly marked by the contrast between zones rich in organic material and zones containing mineral material of varying grain size. In several cases, horizontally oriented organic zones appear to be dis- placed by normal faults. These faulted sediments are found in zones adjacent to the larger ice wedge complexes, where sufficient forces may be developed during wedge formation to cause minor displacements. The distribution of the silt in the section is indicated, in the ide.alized tunnel sections (Fig. 8, 9). The most striking gradation in the color of the sediments was found in the upper portion of the tunnel shaft in and just below the active layer. The upper silts were mottled, had a red-brown to brown coloration, and graded to the more typical brown-gray silts at a depth of 5 ft. Ground ice One of the more obvious physical differences in the appearance of the fine- grained sediments in the tunnel section is caused by the varying amounts of ice in the silt. The ice types can be divided into two general groups: (1) the small lenses and masses formed by ice segregation, referred to as Taber ice (Pdw~, 196~), segregation ice or hair ice (Fig. 10), and (Z) the more massive struc- tures, the large follated ice wedges and the large clear masses (buried Aufeis) (Fig. 8, 11). The large volume of ground ice incorporated in the sediment is unique for both geological and engineering reasons. The large truncated ice wedges found in the section provide an excellent geological tool for determining the past de- positional and climatic conditions. Large volumes (as great as 80%) of inter- stitial ice would tend to impart strength properties to the material similar to ice itself. All the data on sediment physical properties were gathered from the more silty members containing the first type of ice. The lenses varied in size from small veinlets with hairline dimensions to large lenses and bands of ice often GEOLOGY OF THE USA CRREL PERMAFROST TUNNEL 13 lt'igure 10. Lenses of segregation ice typical of the large types, in the exposure of sra. Z+05. Figure 11. Flat-topped ice wedge atsta. 3+55 over- lain by sands that contain fluvial structures. Sampled zone at the base of the wedge provided material for de- termination of an average age of the wedge development. 14 GEOLOGY OF THE USA CRR_EL PERMAFROST TUNNEL several tenths of an inch in thickness and several inches in length. In most cases the ice volume is great enough so that individual blocks or peds of min- eral material are completely surrounded by a matrix of ice. Ice volumes of this material ranged from 54 to ?9%. There are several areas along the tunnel exposure in which an abundance of both types of massive ice is present (sra. 0+90, 1+10, 1+35, l+4Z, 2-+05, Z+30, Z+95, 3+15, 3+50). Even though these structures are quite large they make up a small part of the total ground ice volume of the tunnel. Most of the wedge configurations are very complex with trends that are difficult to deter- mine without a study of the wedge foliation patterns. The clear structureless ice, referred to as Aufeis, as found at sra. Z+30, is thought to originate as pond ice, or a spring or stream icing at a paleosur- face, the ice becoming incorporated in the frozen section by rapid burial as a result of slumping or the flow of thawed mineral material. The massive ice in the shaft is restricted to three zones that contain small wedges less than 9 in. in width, except for the large wedge at the base of the shaft (Fig. 9). This large foliated ice body overlies clear ice that is not typi- cal of that usually associated with ice wedges. Almost all of the wedges in the exposures have flat tops that may reflect some interruption in their formation. This aspect of the wedges is discussed in the following section. Relative dis- tribution of the large ice features is shown in Figure 8. The mechanics of formation of these wedge structures has been described by Taber (1943), Black (1951, 195Z), Lachenbruch (1960, 1963) and P6w~ et al. (1965b). Chemical gradient Ten samples from the vertical shaft and five from the tunnel were pro- cessed to determine both the tota.! cation ~ontent of the extracted soil water, and the organic carbon to nitrogen ratio. I~ was hoped that these parameters could be used in conjunction with the standard geological methods ta establish more positively the geological and environmental history of the area. Specific conductanoe was determined on the soil water extracted from the thawed samples by the vacuum filter technique. The total concentration of Ca, Mg, K, and Na was determined. The methods used are reported by Brown (1966) and O'Sullivan (1966). Total cation concentration versus conduc- tance provided a correlation coefficient of 0.98, suggesting that additional data on the Fairbanks silts could be easily obtained without detailed chemical analy- sis by use of this relation. With the milliequivalent/li.ter values available the relative chemical concentration can be expressed as meq/100 g of oven-dried soil. This expression combines the meq/1 values'determined by specific con- ductance with the moisture content of the sample in the equation: meq/1 x moisture content meq/100 g - 1000 The values for total cation concentration in the vertical section show a marked break in the chemical profile with depth (Fig. 1Z, 13). The values for total cation concentration expressed in meq/100 g of oven-dried soil averaged 0.31 above the break (Z7 ft) and Z.79 below it. This increase in total cation concentration below the break can be used as a possible ind. icator of varying conditions in the depositional environment, during and after deposition. A reasonable assumption is that the longer the material is subjected to thaw the longer the time availabl~ for freshening of the .sediment by removal of the soluble salts by the ground water. GEOLOGY OF THE USA CRREL PERMAFROST TUNNEL Figure 1Z. ' ' ' Sum of CATIONS i , l rneq/lOOg Chemical concentration with depth in meq/1.. 15 IDEALIZED TUNNEL SECTION FAIRBANKS, ALASKA.- DEPTH (ft) 0 I0 20 3o 40 ~ o o,,o °~--~--~---'f~--_ _o Ooo,~ v ~ I o *-' O O o O ~~ ~/~' ..... BEDROCK meq/~ 0 20 40 , I , CHEMICAL PROFILE Figure 13. Ice wedge distribution and relative position of ra- diocarbon dates from the tunnel section. It was anticipated that' significant differenceS between.organic carbon and nitrogen ratios in the section might reflect major changes in the post-deposi- tional environments. Only minor variations in the values exist, with ratios ranging from 9.Z to 13.6, and averaging 10.6. Since the ratios represent such a small range it is difficult to establish if the variations are meaningful and what the concise reason for the variations might be.. Although 'the values do seem to reflect the observed chemical break in the section, the average of the 16 GEOLOGY OF THE USA CRREL PERMAFROST TUNNEL two samples above the break is '9.4 in contrast to 10.6 for the three samples below the break; again this is only a minor difference to which little signifi- cance can be attached. These ratios are somewhat lower than those found in the present day Fairbanks surface soils (Rieger et al., 1963). STRATIGRAPHY A study of the stratigraphy of the section ~eveals a record of the past climatic history of the area, based upon the structure and distribution of the ice wedges, chemical gradients, sedimentary structures, radiocarbon dates, and the lithology of the material exposed along the tunnel section and vertical ventilation shaft. Four samples were selected for radiocarbon dating from the vertical shaft and seven from the tunnel. A variety of datable material was available from the massive silts which contain the large .volume of organic material -required for dating purposes. Th~s material is made up of small organic fibers, plant fragments and rootlets, which constitute from 1.5 to 7.5% of the se'diment'vol- ume. The material is incorporated in the silts' as masses and blocks of peaty material and as individual rootlets and fibers with a°spacing similar to that found in contemporary near-surface soil horizons. In both. the tunnel section and in the vertical shaf.t woody material is also exposed, consisting of logs and twigs, and inarticulate segments of large woody bushes and trees. Bone frag- ments of large vertebrates were also found throughout the section and provided additional datable material. In contrast to the conventional datable huaterial the relative age of several of the large wedge structures was determined from organic residue and amorphous plant material extracted from the melt of large volumes of ice from the wedges, similar.to the technique first used by Brown (1966) at Barrow. The samples processed from the shaft consisted of fine fibrous vegetal material such as rootlets, stems, and plant fragments dispersed in varying concentrations in the frozen silt. The samples submitted for dating were care- fully sieved and sorted so that only similar types of material would be pro- cessed. Table II gives the location, material and age of each sample. Their' relative stratigraphic positions in relation to the other samples dated are shown in Figure 9. The sample locations in the vertical shaft were selected"to,allow esti'mates of rates of deposition to be made and to determine the relationship between the age of the sediments and the striking chemical gradients in the section. In addition, samples selected adjacent to and below the tops of buried ice wedges provided informaiion on the chronology of events responsible for termination of wedge growth. Rough approximations of the depositional rates can be made from t~e two. samples highest in the section, although obviously these rates may have varied greatly 'throughout the 6-ft section. The dates for. depths of 6 ft (I-Zll8) and lZ ft (I-Zl19) suggest that a minimum of 6 ft of sediment was deposited be- tween the surface and the first sample in ?000 years and that the next 6 ft was deposited during the next 1500 years. The second sample, I-Z.119, was adjacent to and just below the top of a small flat-topped ice wedge. GEOLOGY OF THE USA CRREL PERMAFROST TUNNEL Table II. Samples dated. TUNNEL Sample no.* Loc ation Mate rial 1-1369f 0+59 Log 1-1370]~ 1+00 Log 1-1841 3+56 Twig 1-1842 3+55 Ice wedge residue I- 1843 2+05 Ice wedge residue I-g196f 0+15 Bone I-Z197t 0+15 Bone Age (years) 11,400m450 (9,450 BC) 11, 000±280 (9,050 Bc) 33,700+2500 -1900 (31,700 BC) 31,400+Z900 -Z100 (zg, 400 Bc) 32,300+2000 -1600 (30,300 BC) 13,470±420 (~ 1,5ZO ~C) 14, 280±230 (12,330 BC) Depth from surface VERTICAL SHAFT 1-2118 6 ft Fine fibrous organic 1-2119 1g ft Fine fibrous organic I-Z1Z0 26 ft Fine fibrous organic I-Z1Z1 34 ft Fine fibrous organic 6, 97om135 (5, ozo Be) 8,460mZ50 (6, 510 BC) 2, 510*570 560 ~c) 30,700+g, 100 -1,6OO (z8, ?oo Bc) * Dating was by Isotopes, Inc., Westwood, New JerseY. J~ Samples acquired and submitted by Dr. G. Swinzow. 17 18 GEOLOGY OF THE USA CRREL PERMAFROST TUNNEL The third date in the. series (I-Z1Z0) was discarded as the dating lab implied doubt about its validity because of the small sample size and low percent of car- bon. The oldest date' from lt, his secti'on was 30,700 years (at 34 ft) which again compared favorably with 'depth-age relationships from the other dated sections in the Fairbanks area (P~w~, 1958), on Ready Bullion Creek (P6w6 et al., 1965a) and with dated material almost immediately below the shaft in the tunnel section (I-1841, 1-184Z). In the tunnel, dates of 9450. and 9050 years BC were obtained from logs col- lected near the portal at sra. 0+59 and 1+00, approximately 33 ft below the sur- face, in zones containing abundant woody material (Swinzow, 1965, personal com- munication). The sediments in these sections are convoluted and distorted. Disarticulate bone material was collected at sra. 0+15 from the contorted gravel zone, approximately 5 ft stratigraphically lower in the section than the 9000 year BC dates. This material yielded ages of ll,SZ0 and 1Z,330 years BC. The material was obviously .retransported and possibly stream deposited. The large ice vwedges at'sra. Z+05 and 3+55, which are stratigraphically lower than the preceding samples, provided average ages of 30,000 and Z9,400 years BC respectively. The dated residue was concentrated from the melt of approximately 3 ft3 of ice, 40 and 4Z'ft belov~ the surface. The residue originated from surface water rich in organic and mineral material which percolated into and filled the repetitive contraction cracks from a paleosurface. The oldest material dated was a small twig from the fluvial sands above the flat-topped wedge at sra. 3+55. The sandy material vwas probably deposited in drainage channels which formed after the truncation of the wedge. The 31,700 BC date for the tvwig suggests that the woody material was retransported and does not date the time of deposition of the sands. l~igure 13 presents an idealiM~ed summary section showing the distribution and relative size of the ice wedges in the section and associated radiocarbon dates and chemical profile. The ice wedge structures, particularly the presence or absence and size of the buried ice vwedges, and the relationship of the surrounding sediments to the wedge can be particularly useful in interpreting the geological and climatological history of an area (McCulloch et al., in press; Brown, 1965, 1966~ P~w~ et al., 1965a). Flat-topped buried wedges may indicate a degradation of the perenn-'~al"'~y frozen ground and an interruption in vzedge development, a possible indication of (1) a regional~varming, or (Z) some erosional or depositi0nal event. Such wedges may reflect a complex two-stage development where a wedge was trun- cated and conditions then became rigorous enough for the wedge to again become' active. This renewed growth is often indicated by a small wedge that extends upxvard from the top of the large flat-topped mass, as .shown in Figure 11. The ice wedge structures can be broken into tv¢o groups based on their size. In the upper 30 ft of the section the vwedges are very small and from the limited exposures none appear to exceed 1 ft in width, in contrast to the exceedingly large forms as much as 3-6 ft in width found below the 30-ft depth. The possible truncation and burial of the small wedge highest in the section probably took place no more than 8500 years ago. The actual time required for the formation of a wedge this size is very short, several hundred years under optimum conditions. GEOLOGY OF THE USA CRREL PERMAFROST TUNNEL 19 The size and position of this small wedge corresponds with other buried flat-topped wedges found in other exposures in the Fairbanks area 1952). A section on Ready Bullion Creek also reveals several buried flat- topped wedges within 10 ft of the surface. Dating of these sections indicates that they may l~ave been truncated at the end of Wisconsin time (lmew~ et al., 1965a). The wedges are reported to be unconformably overlain by silts of recent age that retain evidence of sedimentary structures, in contrast to the massive Wisconsin silts. The similarities between the two locations based on the limited arnount of exposure available in the tunnel shaft are the similar depths to the top of the first flat-topped ice wedge in the section and the age of the sediments in the upper 10-15 ft of section. The upper 6 ft of sediment in the tunnel section is not bedded as it is in the Ready Bullion section. Instead it has a massive marbled appearance with a reddish to gray coloration, an indi- cation of oxidation and possible decomposition of the organic material incor- porated in the upper section. The differences in the index properties between the young material in the upper part of the section and the V~isconsin age sedi- ments can be seen in Table I. The other small wedges found at irregular intervals above the 30-ft break 'can be interpreted as indicating fairly rapid deposition with few periods with' a stable land surface, or thermal conditions conducive to wedge growth. The break previously mentioned at the 30-ft depth as indicated by the radio- carbon dates and chemical gradients is also suggested by the striking difference in the size of the ice wedges. The large wedge forms are exposed below the break at sta~ 0+90, 1+10, 1+30, Z~+00, Z+95, 3+15 and 3+55. These large wedges suggest a period of stability of the land surface of sufficient duration for the wedges to attain their la~ge size. CONCLUDING STATEMENTS Two recognizable unconformities appear in the section. The upper uncon- formity at a depth of 10 ft is marked by a small ice wedge and a change in the nature of the sediment from reddish gray mottled oxidized silts in contrast to the more organic-rich amorphous silt below the break. At a depth of approxi- mately 30 ft the second unconformity seems to be apparent. It is marked by the change in size of the ice wedges, as well as the flat-topped forms all at the same stratigraphic position, the jump in the radiocarbon dates from 14,000 to 30,000 years and the Z0-fold increase in chemical concentration with depth. Based on the above factual stratigraphic information and a knowledge of events during the late Pleistocene time in other areas, past events in the tun- nel section can be interpreted. The upper unconformity can be found, in other sections in the Fairbanks area and is interpreted as representing degradation of the frozen ground during a period of widespread regional warming (the hypsithermal) sometime between 4000 and 8500 years ago. This event appears robe recorded in the section by a small flat-~topped wedge occurring in the upper portion of the vertical shaft, and bya change in lithology of the sediment. Dates from this horizon are be- tween 50Z0 and 6510 years BC. The sediments above the break are thougbt, to be retransported silts of recent age, overlying the late Wisconsin silts. 20 GEOLOGY OF THE USA CRREL PERMAFROST TUNNEL The most obvious "unconformity" at a depth of approximately 30 ft is well documented in the tunnel section. This unconformity was probably caused by some regional warming or local depositional or erosional event. Additional evidence for an unconformity at this depth in the Fairbanks area is suggested by the dates from the Ready Bullion section, where a thick layer of relatively young sediments similarly overlies sediments 30,000 years old. The unconformity is not marked by any apparent changes in the physical properties of the material that can be seen in the tunnel section above or below the break with the exception of the chemical profile and the size of the ice %vedge structures. A warming event, if responsible for its formation, may correlate with an interstadial in mid-Wisconsin time. This warm interval is thought to be responsible for high stands of the sea between Z7,000 and 35,000 years ago which is referred [o as the Worenzofian transgression (Hopkins, 1966). Evidence for this transgression has been found in several coastal areas in Alaska (Sellmann et.al., 1965; Hopkins, 1966). The large size of the wedges also suggests that depositional rates were fairly slow during the period of wedge development so that a stable land surface could develop from which the large wedges could form. Second cycle development in these large forms is suggested by small cracks and secondary wedges extending upward from the top of the large forms. It can also be concluded that within the last 30,000 years a minimum of 30 ft of silt was deposited, under greatly varying depositional conditions and rates, and that all of the sediment examined in section with the exception of some of the gravels low in the section near the tunnel portal are of Wisconsin age. The sedi- ments in the lower 15 ft represent events that took place prior to the last 30,000 years. LITERATURE G,ITED Black, R.F. (1951)_Structure in ice wedges of Northern Alaska, Geological Society of America, Bulletin, vol. 6Z, p. 14Z3-14Z4. (!95Z) Growth of ice-wedge polygons in permafrost near Barrow, Alaska, (Abs.); Geological Society of America, Bulletin, vol. 63, p. 1Z35- lZ36. Brown, J. (1965)Radiocarbon dating, Barrow, Alaska, Arctic, vol. 18, no. 1, p. 37-48. (1966) Ice wedge chemistry and related frozen ground processes, Bar- row, Alaska, Proceedings of the International Permafrost Conference (National Academy of Sciences - National Research Council), Publication 1Z87, p. 94-97. Crawford, J.D. (1965) Drilling logs, United States Smelting, Mining and fining Co., unpublished. Dingman, S.L. (1966) I-Iydrologic studies of the Glenn Creek drainage basin near Fairbanks, Alaska - Preliminary report, U. S. Army C~ld Regions Research and Engineering Laboratory (USA CRREL) Special Report 86. Flint, R.F~. (1957) Glacial and Pleistocene geology.. New York: John Wiley and Sons, Inc., p. 439. GEOLOGY OF THE USA CRREL PERMAFROST TUNNEL LITERATURE CITED (Cont'd) Hopkins, D.M. (in press) Bearing land bridge. Stanford University Press. Lachenbruch, A.N. (i960) Thermal contraction cracks and ice wedges in per- mafrost, U. S. Geological Survey, Professional Paper 400-B, p. B-404- 406. (1963) Contraction theory of ice_wedge_.~olygons: A quali- tative discussion, Proceedings of International Permafrost Conference, National Academy of Sciences - National Research Council, Publication 1Z87, p. 63-71. McCoy, J.E. (1964a) Use of mechanical system to tunnel in permafrost, USA CRREL Technical Note (unpublished). (1964b) Initial planning and site selection for Project 6.1, Exca- vation project in permanently frozen Alaskan silt, USA CRREL Technical Note (unpublished). (1964c) Selection and modification of mining machine to tunnel in permafrost, USA CRREL Technical Note (unpublished). 1V[cCulloch, D.S.; Taylor, J.S.; and Rubin, Meyer (in press)Stratigraphy non- marine mollusks and radiometric dates from Quaternary deposits in the Z1 Kotzebue Sound area, Western Alaska, Journal of Geology. Mettle, J.B., Jr. (1937)The Yukon-Tana'na Region, Alaska, U. S. Geological Survey Bulletin 872, 276 p. O'Sullivan, J.B. (1966)Geochemistry of permafrost, Barrow, Alaska, Pro- ceedings of the International Permafrost Conference (National Academy of Sciences - National Research Council), Publication 1Z87, p. 30-3?. P~w~, T.L. (195Z) Geomorphology of the Fairbanks area, Stanford University, Ph.D. Thesis, ZZ0 p. (1955) Origin of the upland silt near Fairbanks, Alaska, Geologi- cal Society of America Bulletin, vol. 66, p. ~;'99-7Z4. (1958) Geology map of the Fairbanks (D-Z) quadrangle, Alaska, U. S. Geological Survey, Geological quadrangle Map GQ-il0. et al. (1965a)_rINQUA Guidebook for field conference F (Central and South Central Alaska), 141 p. et al'J (1965b) Ice wedges in Alaska-classification, distribution and climatic significance, Proceedings of the International Permafrost Confer- ence (National Academy of Sciences - National Research Council), Publication 1Z87, p. 76-81. Rieger, S.; Dement, J.A.; and Sanders, D. (1963)Soil survey of Fairbanks area, Alaska, U. S. Department of Agriculture, Soil Conservation Service, with cooperation of Alaska Agricultural Experimental Station. Russell, F. (1963) Heat removal from tunnels in frozen earth materials, USA CRREL Technical Note (unpublished). Sellmann, P.V.; Brown, J.; Sdhmidt, R.A.M. (1965)(Abs.) Late-Pleistocene str__a_tigraphy, Barrow, Alaska, International Association for Q~aternary Research, VII International Congress. GEOLOGY OF THE USA CRtLEL PERMAFROST TUNNEL LITERATURE CITED (Cont'd) Swinzow, G.K. (in prep.) Tunneling by a continuous mechanical method, CRREL Technical Report. USA Taber, S. (1943) Perennially frozen ground in Alaska: Its origin and history, Geological Society of America Bulletin, vol. 54, p. 1433-1548. (1953) Origin of Alaska silts, American Journal of Science, vol. 251, p. 3Z1-336. (1958) Complex origin of silts in the vicinity of Fairbanks, Alaska, Geological Society of America Bulletin, vol. 69, p. 131-136. Tsytovich, N.A. and Sumgin, M.I. (1937) Principles of mechanics of frozen ground, Akad. Nauk SSSR, 432 p. 1. ORIGINATING ACTIVITY (Corporate author) U.S. Army Cold Regions Research and Engineering Laboratory, Hanover, N.H. Unclassified ( ( Secudt¥ Classification DOCUMENT CONTROL DATA- R&D (Security claleiftcation o! title, body of abltract and indexin~ annotation must be entered when the overall report i~ cl,~$sified) fl a. REPORT SECURITY C LASSIFICATION Unclassified b. GROUP 3. REPORT TITLE GEOLOGY OF THE USA CRREL PERMAFROST TUNNEL, FAIRBANKS, ALASKA 4. DESCRIPTIVE NOTES (Type o! report and inclusive datea) Technical Report AUTHOR(S) (Last name, fitter name, initial) Sellmann, Paul V. 6. REPORT DATE 7a. TOTAL NO. OF PAGES 7b. NO. OF' REFS .Jul y 1967 26 29 Sa. CONTRACT OR GRANT NO. 9a. ORIGINATOR'S REPORT NUMBER(S) b. PROJECT NO. c. DA Task 1VOZ5001A13001 Technical Report 199 9b. OTHER REPORT No(S) (Any other numbera that may be this report) 10. AVAILABILITY/LIMITATION NOTICES This document is available to U.S. government agencies and their contractors from: Defense Documentation Center. Microfilm or photocopy of this document is available at dost of reproduction from: Clearing- house for Federal Scientific and Technical Information. 11. SUPPLEMENTARY NOTES 12. SPONSORING MILITARY ACTIVITY U. S. Army Cold Regions Research and Engineering Laboratory 13. ABSTRACT ' This study provides the pertinent regional and historical geology of the tunnel site and immediate surroundihgs as well as data on the index properties and seismic velocities of the material through which the tunnel passes. The tunnel, located in the discontinuous permafrost zone, is discussed with emphasis, on bedrock, gravel, silt, ground ice, and chemical gradient. A study of the stratigraphy of the section reveals a record of the past climatic history of the area, based on the structure and distribution of the ice wedges, chemical gradients, sedimentary structures, radiocarbon dates, and the lithology of the material exposed along the tunnel section and vertical ventilation shaft. Two recognizable unconformities appear in the section. The large size of the wedges suggests that depositional rates were fairly slow during the period of wedge development. It can also be concluded that within the last 30, 000 yr a minimum of 30 ft of silt was deposited, most of which is Wisconsin. age. Security Classification Unclassified Security Classific~'~o. -- 14. KEY WORDS LINK A LINK B LINK C -- ROLE WT ROLE ?VT ROLE WT Permafrost tunnels--Alaska -- Glacial ge olog~- -Stratigraphy- -Alaska Geology--Age determination Ground ic e- -Alaska INSTRUCTIONS 1. ORIGINATING ACTIVITY: Enter the name and address 10. 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