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Home My WebLink AboutCO 809CONSERVATION ORDER 809 Milne Point Unit 1. March 29, 2023 Hilcorp application for downhole commingling MPU C-23 2. April 7, 2023 Public Hearing Notice, Affidavit of Publication, Email list STATE OF ALASKA ALASKA OIL AND GAS CONSERVATION COMMISSION 333 West 7th Avenue Anchorage Alaska 99501 Re: THE APPLICATION OF Hilcorp Alaska, LLC for an order authorizing the downhole commingling of production from the Kuparuk River Oil Pool and the Sag River Oil Pool in the Milne Point Unit C-23 well (API No. 50-029-22643-00-00) ) ) ) ) ) ) ) ) ) ) ) ) Docket Number: CO-23-005 Conservation Order 809 Milne Point Unit Kuparuk River Oil Pool Sag River Oil Pool North Slope Borough, Alaska August 24, 2023 IT APPEARING THAT: 1. By letter dated March 29, 2023, Hilcorp Alaska, LLC (Hilcorp) requested authorization under 20 AAC 25.215(b) to commingle downhole production from the Kuparuk River Oil Pool (KROP) and the Sag River Oil Pool (SROP) in the Milne Point Unit (MPU) C-23 well. 2. Pursuant to 20 AAC 25.540, the Alaska Oil and Gas Conservation Commission (AOGCC) tentatively scheduled a public hearing for June 1, 2023. On April 7, 2023, the AOGCC published notice of the opportunity for that hearing on the State of Alaska’s Online Public Notice website and on the AOGCC’s website, electronically transmitted the notice to all persons on the AOGCC’s email distribution list and mailed printed copies of the notice to all persons on the AOGCC’s mailing distribution list. On April 9, 2023, the AOGCC published the notice in the Anchorage Daily News. 3. No protest to the application or request for hearing was received. 4. Because Hilcorp provided sufficient information upon which to make an informed decision, the request can be resolved without a hearing. 5. The tentatively scheduled hearing was vacated, and the period for public comments closed on May 31, 2023. FINDINGS: 1. Hilcorp is the operator of the MPU and the MPU C-23 well in the North Slope Borough, Alaska. 2. The C-23 well was drilled and completed in 1996 and has produced exclusively from the SROP since then. The well has produced a total of 1.2 MMBO. Current production is approximately 100 BOPD. 3. The C-23 is in a portion of the field where production from the SROP and KROP is low, and it is expected that commingled production will extend the life of the well and allow for greater ultimate recovery from both pools. 4. Hilcorp does not believe that the KROP in this area contains enough reserves to justify drilling a new well to attempt to recover those reserves. Conservation Order 809 August 24, 2023 Page 2 of 3 5. The well is a jet pump lifted well that requires approximately 2,400 BWPD to operate, this results in the C-23 well having an effective water cut of 96%. Such a high water cut makes the well less competitive than other production options when competing for the limited capacity of the MPU processing facilities. 6. Hilcorp estimates that commingling production between the SROP and KROP will add 250 to 400 additional barrels per day to the well’s current production. Adding oil from the KROP to the existing SROP production should result in the well producing with a lower effective water cut and thus make it more competitive. 7. The well will have to be recompleted with the jet pump moved up hole in order to allow for the commingled production and it is expected that there will be a slight decrease from the SROP, but it is expected the additional production from the KROP will more than offset the reduction in SROP production. 8. Hilcorp plans to install a downhole check valve in order to prevent crossflow from the higher pressured KROP to the lower pressured SROP when the well is shut in. The check valve can be replaced with a plug if extended shut ins are expected or to allow for isolating the pools to obtain downhole pressures for a given pool. 9. Hilcorp proposes multiple methods in order to ensure production can be allocated properly between the pools. Initially, allocation would likely be based on the difference between what the SROP was producing prior to commingling and the commingled rate. After that Hilcorp proposes using Geochem analysis, verified by testing by difference as needed, on a quarterly basis. CONCLUSIONS: 1. The remaining reserves in the area of the C-23 well are not sufficient to justify drilling a new well to either pool. Thus, the C-23 well is the only option to produce those reserves. Denying commingling would mean that the pools would have to be produced separately. 2. Allowing commingling of production from the SROP and KROP should extend the life of the well beyond what producing from the pools separately would allow be reducing the economic limit rate for each pool because of the combined production and thus should result in increased ultimate recovery from this portion of the field. 3. Crossflow during shut in periods will be prevented by the downhole check valve that will be installed when the well is worked over to allow for downhole commingling. 4. Basing the initial allocation on the difference between the before and after commingling rates and then following that up with quarterly Geochem analysis for production allocation, which has proven itself to provide acceptable results for allocating production between pools with different fluid properties as is expected here, with testing by difference being done as necessary to verify the accuracy of the Geochem allocations will provide an acceptable method for allocating production between the SROP and KROP. NOW THEREFORE IT IS ORDERED: Pursuant to AS 31.05.030 and 20 AAC 25.215(b), the downhole commingling of production between the Sag River and Kuparuk River Oil Pools in the MPU C-23 well is approved as follows: 1. The well must be completed as proposed in the commingling application, with a downhole check valve installed to prevent crossflow. 2. Thereafter, should analysis on samples collected from the individual pools show that the fluids are of different enough composition to make Geochem viable, quarterly Geochem Conservation Order 809 August 24, 2023 Page 3 of 3 analysis shall be used to allocate production between the pools. By difference testing shall be done as needed to assure the Geochem analysis is providing acceptable results for production allocation. 3. Other allocation methodologies may be approved administratively by the AOGCC should circumstances warrant. 4. Copies of all data used to determine the allocation factors shall be submitted to the AOGCC within 30 days of being collected. DONE at Anchorage, Alaska and dated August 24, 2023. Brett W. Huber, Sr. Jessie L. Chmielowski Gregory C. Wilson Chair, Commissioner Commissioner Commissioner RECONSIDERATION AND APPEAL NOTICE As provided in AS 31.05.080(a), within 20 days after written notice of the entry of this order or decision, or such further time as the AOGCC grants for good cause shown, a person affected by it may file with the AOGCC an application for reconsideration of the matter determined by it. If the notice was mailed, then the period of time shall be 23 days. An application for reconsideration must set out the respect in which the order or decision is believed to be erroneous. The AOGCC shall grant or refuse the application for reconsideration in whole or in part within 10 days after it is filed. Failure to act on it within 10-days is a denial of reconsideration. If the AOGCC denies reconsideration, upon denial, this order or decision and the denial of reconsideration are FINAL and may be appealed to superior court. The appeal MUST be filed within 33 days after the date on which the AOGCC mails, OR 30 days if the AOGCC otherwise distributes, the order or decision denying reconsideration, UNLESS the denial is by inaction, in which case the appeal MUST be filed within 40 days after the date on which the application for reconsideration was filed. If the AOGCC grants an application for reconsideration, this order or decision does not become final. Rather, the order or decision on reconsideration will be the FINAL order or decision of the AOGCC, and it may be appealed to superior court. That appeal MUST be filed within 33 days after the date on which the AOGCC mails, OR 30 days if the AOGCC otherwise distributes, the order or decision on reconsideration. In computing a period of time above, the date of the event or default after which the designated period begins to run is not included in the period; the last day of the period is included, unless it falls on a weekend or state holiday, in which event the period runs until 5:00 p.m. on the next day that does not fall on a weekend or state holiday. Jessie L. Chmielowski Digitally signed by Jessie L. Chmielowski Date: 2023.08.24 11:26:40 -08'00' Brett W. Huber, Sr. Digitally signed by Brett W. Huber, Sr. Date: 2023.08.24 12:04:44 -08'00' Gregory Wilson Digitally signed by Gregory Wilson Date: 2023.08.24 12:43:10 -08'00' 2 Notice of Public Hearing STATE OF ALASKA ALASKA OIL AND GAS CONSERVATION COMMISSION RE: Docket Number: CO 23-005 By application dated March 29, 2023, Hilcorp Alaska, LLC (Hilcorp) requests that the Alaska Oil and Gas Conservation Commission (AOGCC) authorize downhole commingling of production between the Kuparuk River Oil Pool and the Sag River Oil Pool in Milne Point Unit (MPU) Well C-23 (PTD 196-016). Downhole commingling regulations (20 AAC 25.215) are in place to prevent waste and to protect correlative rights. Operators are prohibited from producing from, or injecting into, more than one pool (a rock formation where oil and/or gas has accumulated) in the same wellbore without the AOGCC approving the downhole commingling of two or more pools. It is not uncommon for a well to encounter multiple pools. In these situations, normally an operator will first produce from the deepest pool in the well until it is depleted, then plug off that pool and move up to the next pool and repeat the process until all the pools have been depleted. Sometimes one or more of these pools is not large enough to warrant production/injection operations on its own, or there are other reasons to allow commingled production/injection. In these instances, an operator will apply to the AOGCC for an order approving the downhole commingling of two or more pools. The AOGCC reviews the application to assure waste will not occur and all owners receive their share of the production. This notice does not contain all the information filed by Hilcorp. To obtain more information, contact the AOGCC’s Special Assistant, Samantha Carlisle, at (907) 793-1223 or samantha.carlisle@alaska.gov. A public hearing on the matter has been tentatively scheduled for June 1, 2023, at 10:00 a.m. The hearing, which may be changed to full virtual, if necessary, will be held in the AOGCC hearing room located at 333 West 7th Avenue, Anchorage, AK 99501. The audio call-in information is (907) 202-7104 Conference ID: 488 832 875#. Anyone who wishes to participate remotely using MS Teams video conference should contact Ms. Carlisle at least two business days before the scheduled public hearing to request an invitation for the MS Teams. To request that the tentatively scheduled hearing be held, a written request must be filed with the AOGCC no later than 4:30 p.m. on April 26, 2023. If a request for a hearing is not timely filed, the AOGCC may issue an order without a hearing. To learn if the AOGCC will hold the hearing, call (907) 793-1223 after April 27, 2023. In addition, written comments regarding this application may be submitted to the AOGCC, at 333 west 7th Avenue, Anchorage, AK 99501 or samantha.carlisle@alaska.gov. Comments must be received no later than 4:30 p.m. on May 31, 2023, except that, if a hearing is held, comments must be received no later than the conclusion of the June 1, 2023, hearing. If, because of a disability, special accommodations may be needed to comment or attend the hearing, contact Samantha Carlisle, at (907) 793-1223, no later than May 23, 2023. Brett W. Huber, Sr. Chair, Commissioner Brett W. Huber, Sr. Digitally signed by Brett W. Huber, Sr. Date: 2023.04.07 08:26:17 -08'00' From:Carlisle, Samantha J (OGC) To:AOGCC_Public_Notices Subject:[AOGCC_Public_Notices] Public Hearing Notice, Hilcorp MPU C-23 Commingling Date:Friday, April 7, 2023 11:24:13 AM Attachments:CO-23-005 Public Hearing Notice Hilcorp MPU C-23 Commingling.pdf Docket Number: CO 23-005 By application dated March 29, 2023, Hilcorp Alaska, LLC (Hilcorp) requests that the Alaska Oil and Gas Conservation Commission (AOGCC) authorize downhole commingling of production between the Kuparuk River Oil Pool and the Sag River Oil Pool in Milne Point Unit (MPU) Well C-23 (PTD 196-016). Samantha Carlisle Special Assistant Alaska Oil and Gas Conservation Commission 333 West 7th Avenue Anchorage, AK 99501 (907) 793-1223 __________________________________ List Name: AOGCC_Public_Notices@list.state.ak.us You subscribed as: samantha.carlisle@alaska.gov Unsubscribe at: https://list.state.ak.us/mailman/options/aogcc_public_notices/samantha.carlisle%40alaska.gov Bernie Karl K&K Recycling Inc. P.O. Box 58055 Fairbanks, AK 99711 mailed 4/7/23 Adam Garrigus being first duly sworn on oath deposes and says that she is a representative of the Anchorage Daily News, a daily newspaper. That said newspaper has been approved by the Third Judicial Court, Anchorage, Alaska, and it now and has been published in the English language continually as a daily newspaper in Anchorage, Alaska, and it is now and during all said time was printed in an office maintained at the aforesaid place of publication of said news- paper. That the annexed is a copy of an adver- tisement as it was published in regular issues (and not in supplemental form) of said news- paper on AFFIDAVIT OF PUBLICATION ______________________________________ Notary Public in and for The State of Alaska. Third Division Anchorage, Alaska MY COMMISSION EXPIRES ______________________________________ 04/09/2023 and that such newspaper was regularly distrib- uted to its subscribers during all of said period. That the full amount of the fee charged for the foregoing publication is not in excess of the rate charged private individuals. Signed________________________________ Subscribed and sworn to before me this 10th day of April 2023. Account #: 100869 ST OF AK/AK OIL AND GAS CONSERVATION COMMISSION333 W. 7TH AVE STE 100, ANCHORAGE, AK 99501 Order #: W0037295 Cost: $356.8 Notice of Public HearingSTATE OF ALASKAALASKA OIL AND GAS CONSERVATION COMMISSION RE: Docket Number: CO 23-005By application dated March 29, 2023, Hilcorp Alaska, LLC (Hilcorp) requests that the Alaska Oil and Gas Conservation Commission (AOGCC) authorize downhole commingling of production between the Kuparuk River Oil Pool and the Sag River Oil Pool in Milne Point Unit (MPU) Well C-23 (PTD 196-016). Downhole commingling regulations (20 AAC 25.215) are in place to prevent waste and to protect correlative rights. Operators are prohibited from producing from, or injecting into, more than one pool (a rock formation where oil and/or gas has accumulated) in the same wellbore without the AOGCC approving the downhole commingling of two or more pools. It is not uncommon for a well to encounter multiple pools. In these situations, normally an operator will first produce from the deepest pool in the well until it is depleted, then plug off that pool and move up to the next pool and repeat the process until all the pools have been depleted. Sometimes one or more of these pools is not large enough to warrant production/injection operations on its own, or there are other reasons to allow commingled production/injection. In these instances, an operator will apply to the AOGCC for an order approving the downhole commingling of two or more pools. The AOGCC reviews the application to assure waste will not occur and all owners receive their share of the production. This notice does not contain all the information filed by Hilcorp. To obtain more information, contact the AOGCC’s Special Assistant, Samantha Carlisle, at (907) 793-1223 or samantha.carlisle@alaska. gov. A public hearing on the matter has been tentatively scheduled for June 1, 2023, at 10:00 a.m. The hearing, which may be changed to full virtual, if necessary, will be held in the AOGCC hearing room located at 333 West 7th Avenue, Anchorage, AK 99501. The audio call-in information is (907) 202-7104 Conference ID: 488 832 875#. Anyone who wishes to participate remotely using MS Teams video conference should contact Ms. Carlisle at least two business days before the scheduled public hearing to request an invitation for the MS Teams. To request that the tentatively scheduled hearing be held, a written request must be filed with the AOGCC no later than 4:30 p.m. on April 26, 2023. If a request for a hearing is not timely filed, the AOGCC may issue an order without a hearing. To learn if the AOGCC will hold the hearing, call (907) 793-1223 after April 27, 2023. In addition, written comments regarding this application may be submitted to the AOGCC, at 333 west 7th Avenue, Anchorage, AK 99501 or samantha.carlisle@alaska.gov. Comments must be received no later than 4:30 p.m. on May 31, 2023, except that, if a hearing is held, comments must be received no later than the conclusion of the June 1, 2023, hearing. If, because of a disability, special accommodations may be needed to comment or attend the hearing, contact Samantha Carlisle, at (907) 793-1223, no later than May 23, 2023. Brett W. Huber, Sr. Chair, Commissioner Pub: Apr. 9, 2023 STATE OF ALASKA THIRD JUDICIAL DISTRICT 2024-07-14 Document Ref: VYJPB-SXND2-QQMFV-LRWCC Page 6 of 65 1 3800 Centerpoint Drive Suite 1400 Anchorage, AK 99503 Phone: 907/777-8300 Fax: 907/777-8301 March 29, 2023 Commissioner Brett Huber Alaska Oil & Gas Conservation Commission 333 West 7th Avenue, Suite 100 Anchorage, AK 99501 RE: Request for Approval of Downhole Commingling –C-23 Well Milne Point Unit Dear Commissioner Brett Huber, Hilcorp Alaska, LLC (HAK),as Operator of the Kuparuk River Oil Pool (KOP) and the Sag River Oil Pool (SOP) within the Milne Point Unit (MPU), approval from the Alaska Oil and Gas Conservation Commission (AOGCC) to commingle production from the KOP and SOP in the MPU C-23 well. Commingling of production from both pools will allow for recovery of a greater quantity of oil, and such production can be properly allocated. HAK requests AOGCC to issue an order authorizing the commingling of production from the KOP and the SOP within the well. Plans are to commence commingling of production from KOP and SOP in the Well by the end of 2023 if approval can be obtained. A technical justification is attached. If you have any additional questions concerning this request, please contact me at 907-564- 5277 or by email at brian.glasheen@hilcorp.com. Sincerely, Brian Glasheen Operations Engineer Hilcorp Alaska, LLC By Samantha Carlisle at 11:19 am, Mar 29, 2023 Digitally signed by Brian Glasheen (4099) DN: cn=Brian Glasheen (4099), ou=Users Date: 2023.03.29 10:14:04 -08'00' Brian Glasheen (4099) MPU C-23 Commingling Application 3/29/2023 Attachment: Technical Justification CC Dave Roby, David Haakinson MPU C-23 Commingling Application 3/29/2023 Introduction Commingling of production within the same wellbore from two pools is permitted under 20 AAC 25.215(b): if the Commission, after notice and opportunity for public hearing, (1) finds that waste will not occur, and that production from separate pools can be properly allocated; and (2) issues an order providing for commingling for wells completed from these pools within the field. Waste Will Not Occur 1. Production Considerations The Well penetrates the KOP and SOP in areas where well rates from both oil pools are very low. The low oil rate combined with jet pump fluid makes the well uncompetitive for facility processing space at times and is shut in frequently for water handling at the MPU facility. Although there is currently no KOP production from the MP C-23 wellbore, the expected rate and remaining hydrocarbons do not justify drilling a standalone well. By commingling production from the two oil pools within the same wellbore, the total oil rate combined with the total jet pump fluid will be far more competitive and allow the well to return to a full- time producer. Consequently, commingling of production from the KOP and SOP within the same wellbore will not cause waste, but rather should allow for recovery of a greater quantity of oil. 2. Hydraulic Impacts on Production The well was drilled in 1996 as a standalone producer in the SOP. Production from the well averages 80-160 stb/d of oil, as shown in Table 1. Combining the 100 bopd with the power fluid (2400 bwpd) needed to lift the well, results in 96% water cut which is currently uncompetitive at the MPU facility. It is estimated that additional production from the KOP will add 250-400 bfpd of production without resulting in a significant change in flowing bottom hole pressure (BHP). MPU C-23 Commingling Application 3/29/2023 Table 1 Well tests from MPC-23, in standard oilfield units An increase in annualized SOP production is expected from commingling due to a decrease in total fluid water cut with the addition of the KOP oil. The combined water cut will make the well more competitive at the MPU facility. Due to the low current SOP production rate, no additional jet pump power fluid (water) would be required to handle additional liquid from the KOP. In a water handling constrained environment, the reduced water-oil ratio results in an increase in oil production rate by utilizing the water elsewhere. Since commingling requires a shallower power fluid injection depth, a small rate impact is expected to the SOP while on production. However, because the oil cut is lower at this point, the impact on oil rates to the SOP is more than offset by additional production from the KOP by the reduced down-time and water-handling benefits. This selective application of commingled production will result in an increase of overall recovery from both the KOP and SOP. 3. Cross flow Because both pools have similar in-situ fluid properties and share the same source of injection water, commingling should not result in formation damage. No fluid incompatibilities have been noted during ongoing surface commingling. Currently, the SOP is on primary depletion and suffers from lack of injection support and will result in a lower BHP than the KOP. The KOP will be water flooded and will have a higher BHP than the SOP. To mitigate any cross flow between the SOP and the KOP, the Well will be equipped with an XN-nipple between the KOP and SOP perforations, as shown in figure 1, to allow isolation of the pools by setting a down-hole check valve that will not allow the KOP to cross flow into the SOP. The XN-nipple can also be used for a down-hole plug for extended shut- ins (>1year) or when separate zone pressure measurements are desired. MPU C-23 Commingling Application 3/29/2023 Figure 1. Proposed commingled completion MPU C-23 Commingling Application 3/29/2023 Appropriate Surveillance and Production Allocation Will Be Assured Appropriate surveillance and production allocation measures will be undertaken to meet reservoir management objectives and to provide an acceptable allocation methodology. Production Allocation In addition to stand-alone tests of the SOP prior to commingling, when commingling commences, quarterly (91-producing days) geo chemical (GC) samples will be obtained and compared with tests by difference when flowing comingled. Fluid samples will be obtained from both pools to verify that GC analysis will allow for metering of pool oil, water and gas to within allocation quality accuracy. See attached SPE paper for more detailed information on this method. After one year of commingled production, GC analysis will be completed biannually and testing by difference will be repeated as necessary to assess production anomalies based on well test results. *Note: Production logs are not obtainable in a jet pump completion. Conclusion Hilcorp requests approval for the commingling of production from KOP and SOP, in MPU C-23. This activity will not create waste and produced liquids and gas from the separate pools can be properly allocated. During the first year of production, geochemical analyses of oil samples will be performed quarterly to verify agreement with test by difference results. Thereafter, it is proposed that geochemical analysis be performed semi-annually to properly manage and allocate long-term production. SPE 144618 Geochemical Allocation of Commingled Oil Production or Commingled Gas Production Mark A. McCaffrey, SPE, Weatherford Laboratories; Danielle H. Ohms, SPE, BP Exploration (Alaska) Inc.; Michael Werner, ConocoPhillips Alaska, Inc.; Christopher Stone, SPE, BP Exploration (Alaska) Inc.; David K. Baskin, Brooks A. Patterson, Weatherford Laboratories Copyright 2011, Society of Petroleum Engineers This paper was prepared for presentation at the SPE Western North American Regional Meeting held in Anchorage, Alaska, USA, 7–11 May 2011. This paper was selected for presentation by an SPE program committee following review of information contained in an abstract submitted by the author(s). Contents of the paper have not been reviewed by the Society of Petroleum Engineers and are subject to correction by the author(s). The material does not necessarily reflect any position of the Society of Petroleum Engineers, its officers, or members. Electronic reproduction, distribution, or storage of any part of this paper without the written consent of the Society of Petroleum Engineers is prohibited. Permission to reproduce in print is restricted to an abstract of not more than 300 words; illustrations may not be copied. The abstract must contain conspicuous acknowledgment of SPE copyright. Abstract Introduction 2 SPE 144618 Methods Allocation of Commingled Oils 1 2 m 1 2 m SPE 144618 3 j j (1) Scaling the raw values for X and Y prior to solving for . (2) Utilizing information revealed by the structure of the variance within the dataset. (3) Eliminating from consideration GC peaks with certain specific characteristics. Testing the Technique 4 SPE 144618 Allocation of Commingled Gases Issue 1: SPE 144618 5 6 SPE 144618 Issue 2: Case Studies Case Study #1: Well Niakuk-43 (NK-43), Greater Prudhoe Bay, North Slope, Alaska SPE 144618 7 Case Study #2: Well S-26, Prudhoe Bay Field, North Slope, Alaska 8 SPE 144618 Case Study #3, Viscous Oil Well #1, North Slope, Alaska Case Study #4, Viscous Oil Well #2, North Slope, Alaska Discussion Advantages of Geochemical Allocation Compared to Production Logging Cost advantages relative to conventional e-line PLT: Advantages relative to coiled tubing or tractor-conveyed e-line PLT Detection of zone performance problems at any point during the life of a well: Applicability to vertical, deviated and horizontal wells: SPE 144618 9 Applicability to pumping wells: Ability to quantify uncertainty: Zonal Production vs. wellbore entry: No risk of sticking a logging tool: Ability to allocate in the absence of flow meter data: Ability to identify problems with flow meter data: Issues Concerning End Member Oils 10 SPE 144618 Summary References Acknowledgements SPE 144618 11 Table 1: Calculated Allocation Results Compared to Actual Compositions for Artificial Mixtures of Oils or Gases Calculated Actual composition of Difference between Geochemical Number Type Allocation Artifical Mixutre Calculated and Parameters Blind Location of Zones Result Prepared by Laboratory Actual Composition Used Test? Well NK-43 2 Oil 13.4% / 86.6% 15.0% / 85.0% 1.6% 48 Yes Well NK-43 2 Oil 47.5% / 52.5% 50.1% / 49.9% 2.6% 48 Yes Well NK-43 2 Oil 78.9% / 21.1% 79.9% / 20.1% 1.0% 48 Yes Well S-26 2 Oil 68.8% / 31.2% 75.0% / 25.0% 6.20% 132 Yes Well S-26 2 Oil 46.1% / 53.9% 50.0% / 50.0% 3.90% 132 Yes Well S-26 2 Oil 20.9% / 79.1% 25.0 % / 75.0% 4.10% 132 Yes Undisclosed Alaska A 2 Oil 65.1% / 34.9% 66.5% / 33.5% 1.4% 209 Yes Undisclosed Alaska A 2 Oil 87.1% / 12.9% 87.85% / 12.15% 0.75% 209 Yes Undisclosed 0140 2 Oil 48.0% / 52.0% 50.1% / 49.9% 2.1% 40 Yes Undisclosed 0140 2 Oil 51.5% / 48.5% 50.2% / 49.8% 1.3% 40 Yes Undisclosed 0140 2 Oil 50.5 %/ 49.5% 49.9% / 50.1% 0.6% 40 Yes Undisclosed 1053 2 Oil 90.4% / 9.6% 91.4% / 8.6% 1.0% 171 Yes Undisclosed 1053 2 Oil 59.9% / 40.1% 59.6% / 40.4% 0.3% 171 Yes Undisclosed 1053 2 Oil 87.2% / 12.8% 86.4% / 13.2% 0.8% 171 Yes Undisclosed 1053 2 Oil 45.4% / 54.6% 44.3% / 55.7% 1.1% 171 Yes Undisclosed 1053 2 Oil 60.2% / 39.8% 59.9% / 40.1% 0.3% 171 Yes Undisclosed 1053 2 Oil 70.9% / 30.4% 70.2% / 29.8% 0.7% 171 Yes Average error of allocation of 2-zone artifical mixtures of oils in this table: 1.8% Undisclosed 1100 2 Gas 50.6% / 49.4% 50.0% / 50.0% 0.6% 8 No Undisclosed 08834 3 Oil 60.2% / 39.8% / 0% 64.5% / 35.5% / 0% 4.3% / 4.3% / 0% 158 Yes Undisclosed 08834 3 Oil 33.5% / 46.7% / 19.8% 39.1% / 40.9% / 20.0% 5.6% / 5.8% / 0.2% 158 Yes Undisclosed 08692 3 Oil 49.2% / 28.9% / 21.9% 48.1% / 29.7% / 22.2% 1.1% / 0.8% / 0.3% 93 Yes Undisclosed 08692 3 Oil 12.9% / 17.2% / 69.9% 10.8% / 19.7 % / 69.5% 2.1% / 2.5% / 0.4% 93 Yes Undisclosed 0140 3 Oil 10.0% / 31.0% / 59.0% 15.0% / 29.9% / 55.1% 5.0% / 1.1% / 3.9% 40 Yes Undisclosed 0140 3 Oil 54.0 %/ 15.0 %/ 31.0% 55.0% / 15.1% / 29.9% 1.0% / 0.1% / 1.1% 40 Yes Undisclosed 48345 3 Oil 28.3% / 30.5% / 41.2% 31.0% / 29.9% / 39.1% 2.7% / 0.6% / 1.1% 138 Yes Undisclosed 48345 3 Oil 20.1% / 22.2% / 57.7% 19.6% / 20.4% / 60.0 % 0.5% / 1.8% / 2.3% 138 Yes Average error of allocation of 3-zone artifical mixtures of oils in this table: 2.0% Undisclosed 0140 4 Oil 10.0% / 18.0% / 29.0% / 43.0% 10.0% / 19.9% / 29.8% / 40.3% 0.0% / 1.9% / 0.8% / 2.7% 40 Yes Undisclosed 0140 4 Oil 18.0% / 25.0% / 36.0% / 19.0% 19.8% / 29.9% / 39.1% / 10.6% 1.8% / 4.9% / 3.1% / 8.4% 40 Yes Undisclosed 0140 4 Oil 42.0% / 7.0% / 17.0% / 34.0% 40.1% / 10.2% / 19.8% / 29.9% 1.9% / 3.2 % / 2.8 %/ 4.1% 40 Yes Undisclosed 48345 4 Oil 30.7% / 25.9% / 11.0% / 32.4% 30.0% / 30.0% / 10.0% / 30.0% 0.7% / 4.1% / 1.0% / 2.4% 137 Yes Undisclosed 48345 4 Oil 30.0% / 43.1% / 7.7%/ 19.2% 26.3% / 43.7% / 12.7% / 17.2% 3.7% / 0.6%/ 5.0% / 2.0% 137 Yes Undisclosed 48345 4 Oil 9.6% / 10.3% / 39.1% / 41.0% 10.0 % / 10.0% / 40.0% / 40.0% 0.4% / 0.3% / 0.9% / 1.0% 137 Yes Undisclosed 48345 4 Oil 21.0% / 26.9% / 22.7% / 29.4% 20.3% / 29.5% / 20.0% / 30.2% 0.7% / 2.6% / 2.7% / 0.8% 137 Yes Average error of allocation of 4-zone artifical mixtures of oils in this table: 2.3% 12 SPE 144618 V I II III and IV Lines Superimposed Figure 1. The lines representing the 5 equations intersect at a unique point (a point corresponding to the allocation solution). This figure demonstrates a difference between projects that do and do not use isotope data: Where only concentration data are used, every equation is a line with a negative slope with positive intercepts on both axes. In the general case, every equation forms a hyperplane in n-dimensions (where n is the number of end-members) with positive intercepts on each dimension. In contrast, the equations that govern mixing of isotopic values are lines that pass through the origin. In the general case, equations that govern mixing of isotopic values describe hyperplanes in n-dimensions (where n is the number of end-members) that pass through the origin. Figure 2. The lines representing the 5 equations do not intersect at a unique point because we introduced “error” into the isotope data for the commingled gas. Linear algebra (i.e., a least squares regression) can then be used to derive the best “compromise” solution in a manner just as was described previously for the allocation of commingled oils. SPE 144618 13 Figure 3. Location map for the North Slope of Alaska. The 4 case studies discussed below are located. 14 SPE 144618 0.0% 10.0% 20.0% 30.0% 40.0% 50.0% 60.0% 70.0% 80.0% 90.0% 100.0% 10/25/2005 2/2/2006 5/13/2006 8/21/2006 11/29/2006 3/9/2007 6/17/2007 NK-43 Sag vs. NOP Oil Splits Sag Geochem NOP Geochem Sag PLT NOP PLTSag Geochem NOP Geochem Sag PLT NOP PLT Figure 4. Well NK-43 Comparison of geochemistry-derived production splits with Production profile Log (PLT)-derived production splits. SPE 144618 15 Geochem% Aurora Oil Geochem % Prudhoe Oil 10/10/08 PLT Aurora Oil %10/10/08 PLT Ivishak Oil % 2/16/09 PLT Aurora Oil %2/16/09 PLT Ivishak Oil % Figure 5. Well S-26 Comparison of geochemistry-derived production splits with Production Log (PLT)-derived production splits. The average Aurora oil split over the commingled test period from the 2 PLT’s was 53%. This value closely matchesthe average of the geochemical analysis Aurora oil split of 55% (for all 7 samples) or 53% (for 6 samples, excluding the initial sample when the Prudhoe Oil Pool was just reopened and was cleaning up). 16 SPE 144618 Sand 2 Water Injection Shut in 6/6/2006 Sand 2 Sand 3 Figure 6. This viscous-oil well commingles production from two sands: Sand 2 (higher-API-gravity oil) and Sand 3 (lower-API- gravity oil). The red and green symbols show the geochemistry-derived allocation results. Prior to 6-6-2006, production from Sand 2 was supported by water injection. Once the water injection was shut in, the geochemistry-derived value for the fraction of production from Sand 2 begins to systematically decrease. The allocation result is also consistent with the drop in API gravity of the commingled oil that occurs after the 2 injection support is shut-in. SPE 144618 17 1J-166 Production Allocation Results 0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 90.0 100.0 Wt %Sand A Sand B Sand D Sand 2 Sand 3 Sand 1 PLT 10/10/2008 Sand 2 IsoSleeve Removed 9/20/2009 Sand 2 IsoSleeve Installed 7/25/-8/18/2008 Figure 7. This viscous-oil well commingles production from three sands: Sand 1, Sand 2, and Sand 3. Between 7-28-2008 and 8-11- 2008, an IsoSleeve was installed that shut off production from Sand 2. The IsoSleeve was removed on 9-20-2009. The geochemistry-derived allocation results (small red, green, and blue symbols) show the fall in Sand 2 production after the IsoSleeve was installed, and show the return of Sand 2 production after the IsoSleeve was removed. During the period the IsoSleeve was in place, a PLT that was run (10-10-2008; large red, green, and blue symbols)) failed to detect production from Sand 1, although the geochemistry was able to detect ~20% Sand 1 production. Back-pressure caused by the PLT tool is believed to be the cause of the PLT being unable to detect the Sand 1 production. The geochemistry method, since it does not involve inserting a tool into the well, does not create any back pressure, and hence is able to detect the Sand 1 production. 18 SPE 144618 Figure 8. Inadvertent “contamination” of a “Sand B” end member with oil from “Sand A” will raise the apparent contribution of “Sand B” to any commingled “Sand A+ Sand B” oils that are allocated using the contaminated “Sand B” end member. This concept is illustrated by the two diagrams shown above. In the top diagram, both end members oils are pure oil from their respective zones. The commingled oil in that diagram has a composition exactly half way between the compositions of the two end members, and is correctly allocated as a 50%/50% mix of oil from Sand A and Sand B. In the bottom diagram, the Sand B end member is “contaminated” with 25% Sand A oil. The effect of this contamination on the allocation result is to erroneously increase the calculated “Sand B” contribution to 67%. Figure 9. These data are not the results of actual analyses, but rather are hypothetical data used here to illustrate a concept. In both the left-hand panel and the right hand panel, the data in the five blue columns are identical. Each blue column represents a commingled oil (Commingled oils B, C, H, D, and E), and each of these commingled oils is made up of different contributions from the same two unknown end members (Oil 1 and Oil 2). For each of those commingled oils, the GC peak heights of 10 GC peaks are measured, and hence each blue column has 10 rows. In the left hand panel (Solution 1), two hypothetical end member oils (Oil 1 and Oil 2) are shown in the yellow columns, and those hypothetical end members can be used to perfectly explain the blue data as perfect mixtures of Oil 1 and Oil 2 (with the values shown in red). In that panel, for example, Oil H can be explained to be 85% Oil 1, 15% Oil 2. The right-hand panel (Solution 2) derives completely different allocation results for the blue data, by simply changing the composition of the hypothetical end member “Oil 2”. In that panel, Oil H can be explained to be 44.44% Oil 1, 55.56% Oil 2. These data are plotted in Figure 10. SPE 144618 19 Figure 10. The upper panel in this figure plots “Solution 1” from Figure 9. The lower panel in this figure plots “Solution 2” from Figure 9. These figures illustrate that without having true end member samples, there are an infinite number of possible allocation solutions to the blue data in Figure 9.