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Home My WebLink AboutGMC Data Report No. 206 Cementation exponent in carbonate reservoir of the Wahoo Formation (Le., its relationship to permeability, pore geometry, and hydrocarbon production) as. determined from core of the Husky Oil NPR Operations Inc. (U. S. Geological Survey) Lisburne Test Well No.1 (8,052.0' - 8,066.5'), ARCO Alaska Inc. Prudhoe Bay Unit L2-26 (11,145.5' - 11,165.5'), and ARCO Alaska Inc. Prudhoe Bay Unit L5-24 (11,170.4' - 11,494.5'). Received 7 February 1993 Alaska Geologic Materials Center Data Report No. 206 Total of 34 pages in report i I CEMENT A nON EXPONENT IN CARBONATE RESER yams: ITS RELATIONSHIP TO PERMEABILITY, PORE GEOMETRY, AND HYDROCARBONPRODUC110N by Ali. Turker Submitted in Panial Fulfillment of the Requirements for the Degree of Master of Science New Mexico Institute of Mining and Technology Socorro, New Mexico June 1992 GMC Data Report No. 206 1/34 ABSTRACT Formation evaluaûorr of carbonate reservoirs is more complex than that of sandstone reservoirs. For example, the core analysis of carbonate samples containing open vugs on their surfaces is not the same as analyzing sandstone core samples. This study shows that the well log-derived cementation exponents are as accurate as laboratory derived cementation exponents. Comparison of cementation exponent data derived from both laboratory and well logs shows a very strong cOITelation (correlation coefficient 0.94). The well log based Nugent (1984) technique is more accurate than the Pickett Plot technique in determining cementation exponent (m). This is due to the significant weaknesses of the Pickett Plot method (e.g., this technique averages m for the entire logged interval, the interval must be water wet, porosity values of the interval have to have a wide range). The measured penneability values of most of the samples studied are very low; only a few samples show high to very high values. Permeability ranges widely from 0.04 to 1501.31 md. The Mission Canyon Fonnation has almost all of the highest values, while the Wahoo Fonnation has the lowest values. Diagenesis played a very important role in forming the pore geometries and rock textures of the formations. The tightly interlocking dolomite-crystal fabric formed the lowest permeability values, whereas dissolution caused permeability to be high. The porosity versus formation resistivity factor data show excellent relationship with a correlation coefficient of about 0.90. This indicates that m decreases with decreasing porosity. GMC Data Report No. 206 2/34 'V Cementation exponents in this study range from 1.54 to 3.0. In order to establish a meaningful relationship between cementation exponent and hydrocarbon production~ m must have values greater than 3.0. GMC Data Report No. 206 3/34 TABLE OF CONTENTS ACfq\JOWLEDGEM~....................................................... CT.. .... .............."...... ..... ................. fl...... ............. ............. T ABL.E OF CO ........................................................... US'T OF AGURES................................................................. .. UST OF T ABLES................................................................... . J~D,UCTlON .................... ... ...........'....... ..... ... ........ ............ ... BAC K GROU NO...... ..........._.. .............. ......~......................... .... · . · S'TRA TlGRAP HY. ................ .. ....................... ...... ............... ...... · W'ahoo Formation. ......... ......... ............. ...... .... ... ......... Charles Salt Fonnation. ........ ...... ...... ..................... Duperow Formation.. ....... ..... ............ ... .................. ... Mission Canyon Formation.................................... Red River Formation... .................. ... ... .......... ........ ... Phosphoria Formation...... ....... ......... ....... .......... ...... M ETI-iODS OF INVESTIGATION .......................................... Permeability Measurements............. ......... ........ Porosity Logs............................................................... Sonic l.og............................................................ Density l.og...................................................... Neutron l.og.. ........... .... ..... ... ........ ..... ........... .... Well Log Derived m.......................······················..· Lab Derived m....... ....... .... ...... ............... ....... ......... .... GMC Data Report No. 206 VI PAGE i i iv vi ;x xi 1 9 1 1 11 16 16 16 19 19 21 21 24 24 25 26 27 29 4/34 Thin Section Analysis................................................... Porosity Types....... .... ... ... ... ................ .... ..... ... .... . V uggy Porosity........................ ................. I ntercrystaHine Porostiy................. Microporosity. ........... ............. ........ ... ...... . Other Types of Porosity.................... RES·UL 'TS......................................._................_............................... . Permeability and Porosity..................................... Cementation Exponent......... .......... .......................... ... Relationships Among Petrophysical Parameters All Samples............................................................ \ILJg~)f Por()sit)f ~CirT1~les.................................... Intercrystalline Porosity Samples........... Decfine Curves and m.................................................... Porosity Type Distribution............ .............. ........... Wat100 Format:ion... ........~........ ..... ... II........ ..... ... Charles Salt Formation................................ o uperow Formation. ... ..... ......... ................... ... Mission Canyon Formation.......................... Red River Formation....................................... Phosphoria Formation... ........ .......................... O· . lageneSls. .... .... ...... ... ... ... ... ................. ................. ... ....... .. . . Watloo Formation. .... .......... .... ...... ............. .... .... Charles Salt Formation.................................. o uperow FOmlation......... ........ ........... ... ........ ... Mission Canyon Formation............................ GMC Data Report No. 206 vu 32 33 33 36 37 37 38 38 38 44 44 58 58 59 59 70 70 70 70 71 71 71 71 72 73 74 5/34 Red River Formation...................................·.. Phosphoria Formation...... ............ ...... ........... o JSCUSS JON............................................................................. ... · . Analytical Techniques........ ....... .... .......... ................ Permeability and Porosity................................... Cementation Exponent............................................ Relationships Among PetrophysicaJ Parameters Hydrocarbon Production and m............................ Petrographic Analysis...... .......... ................................ CONC LU SIGNS._................... .... ... .... ..... ........... ............. ............ .. · FUTIJRE WORK................. ......................................................... · · REFER~CES CITED................................................................... · Af:JPENO IX J..................................................................................... · APPENDIX II.................................................................................... GMC Data Report No. 206 VlU 75 75 77 77 77 80 80 81 82 83 85 86 90 92 6/34 STRA TIGRAPHY Fonnations used in this study are from three different basins: The Wahoo Fonnation of the Lisburne Group is part of the North Slope Basin, (Fig. 3); the Charles Salt, Duperow, Mission Canyon, and Red River Formations are pan of the Williston Basin (Fig. 4); the Phosphoria Formation is part of the Big Horn Basin (Fig. 4 ). Wat}oo Formation: The Lisburne Group (Mississippian-Pennsylvanian) is divided into two formations on the west end of the Sadlerochit Mountains of the Eastern Brooks Range: the Wahoo (Pennsylvanian) from which the samples for this study were gathered and Alapah (Fig. 3,Okland, et aI., 1987). The stratigraphic boundary between the Wahoo and Alapah Formations is canmonly characterized by a sharp contact (Mamet and Armstrong, 1972). The marine Wahoo FormationlLimestone shows different lithological characteristics in the lower and upper parts (Wood and Armstrong, 1975). The lower part of the Wahoo consists of medium-grained bryozoan crinoid wackestones and packstones. Coarse-grained bryozoan crinoid grainstones and a 45-foot-thick oolitic grainstone interval form the uppermost rocks of the Wahoo Formation. This portion is thought to have been deposited in a strongly agitated open-shoal environment containing oolite banks (Wood and Armstrong, 1975). The predominant porosity types are vuggy, intercrystalline, and fracture (Okland, et al.. 1987). 11 7/34 GMC Data Report No. 206 '-- RESULTS Data was obtained from laboratory, weJIlog, and petrographic analyses. Lab analysis included permeability, porosity, fonnation resistivity factor, and cementation exponent measurements. Well log analysis consisted of obtaining porosity readings from sonic. neutron, and density logs. Cementation exponents were calculated based on these porosity values. Petrographic analysis ,included determination of porosity types and diagenetic history for all fonnations. Perrpeaþility 311rl Porosity: The measured penneability values of most samples are poor to fair (Le., < 10 md) and only a few samples show good to very good values (Le., > 10 md.. Table 1). Permeability values range from 0.04 to 1501.31 md. The highest permeability samples are from the Mission Canyon Formation, the lowest from the Wahoo Formation. Porosity va! ues of most samples are fair to very good (i.e., > 10 %) and only a few samples have negligible values (i.e.. < 5 %). Porosity values range from 1.2 to 30.8 %. <";ementation· Exponent: As mentioned in the methods section, m was derived by various techniques. These methods were standard lab, special lab, and well logs. Plots were made to show the degree of correlation between these techniques. The majority of standard lab-derived m values are below 2.0 and the highest is 2.31 (Fig. 9). The majority of special lab-derived m values are above 2.0 and the highest value is 2.91 (Fig. 9). The well log-derived m data shows very high GMC Data Report No. 206 38 8/34 Table 1. Porosities derived from both lab and well logs and measured penneabilities of samples used in this study. GMC Data Report No. 206 9/34 SAMPLE FORMATION WB.L NAME POROSITY POROSITY PERM. NAME <",lab.) (%. Logs) (md) 7 CHARLESSAL T 33-1NP 19.6 20.6 11.19 8 CHAAI..ES SALT 33-1NP 10.0 10.9 2.86 49 CHARlES SAlT 33-1NP 13.7 14.4 1.80 PiT CHARLES SALT 33-1 NP 88 CHARLES SALT 33-1NP 89 CHARLES SALT 33-1NP 6 CUPEROW 33-1NP 13.5 14.0 33.12 11 CUPEROW 3D-8lUTTS 11.6 11.0 31.99 13 CUPEROW 33-1NP 9.5 9.5 6.67 14 OUPEROW 3D-9lUTTS 7.9 11.0 0.68 45 OUPEROW 3D-9lUTTS 12.4. 15.7 32.46 51 OUPEROW 33-1 NP 8.2 8.2 19.75 55 OUPEROW 30-9 wns 22..7 17.2 829.81 58 DUPEROW 3D-9 tunS 61 OUPEROW 33-1NP 16.9 16.9 1.02 90 DUPEROW 33-1 NP 91 OUPEROW 33-1NP 92 DUPEROW 33-1 NP 93 OUPEROW 33-1 NP 62 WAHOO USBURNE.L..5-24 12.0 11.0 1.66 63 WAHOO USBURNE ~4 4.3 7.0 0.08 64 WAHOO usaURNE f.5.24 3.4 4.5 0.04 65 WAHOO USSUANE L5-24 4.0 5.0 0.05 66 WAHOO USBURNE~4 3.4 9.6 0.30 67 WAHOO USSURNE 1.5-24 7.5 14.6 0.25 68 WAHOO USBURNE L5-24 4.4 9.8 0.13 69 WAHOO LISBURNE 1..5-24 11.8 16.1 1.61 70 WAHOO USBURNE J.5.24 3.6 4.5 0.07 94 WAHOO USSURNE L2.æ 10.1 8.0 1.02 95 WAHOO USBURNE L2.æ 11.1 7.8 1.25 96 WAHOO USSURNEL2-28 11.1 13.5 1.40 97 WAHOO USSURNE L2.æ 5.6 6.9 0.38 98 WAHOO USBURNE 1.2-28 99 WAHOO USSURNEL2-28 4.4 4.5 0.12 71 WAHOO USBURNETESTWB.L #1 4.5 5.0 0.22 72 WAHOO USSURNETESTWB.L #1 4.6 5.0 0.25 73 WAHOO USBURNETESTWBJ. #1 2.8 9.0 0.14 74 WAHOO USBURNETESTWBJ.#1 2.S 10.0 0.15 75 WAHOO USBURNETESTWBJ. #1 5.0 5.0 0.17 76 WAHOO USBURNETESTWB.L #1 2 M.CANYON 1-28 DONALD PCI t:HSON 10.2 14.8 0.06 9 M.CANYON 1..æ DONALD PETERSON 3.3 20.0 0.30 15 M.CANYON 1-28 DONAlD t't:1 ~N 20.1 10.3 1415.75 16 M.CANYON 1-28 DONALD PETERSON 12.4 9.8 1S01.31 17 M.CANYON 1-28 DONALD PETERSON 4.6 2.3 0.06 18 M.CANYON 1-28 DONAlD PETERSON 22 M.CANVON 1-28 DONALD PETERSON 4.6 1.8 0.08 24 M.CANVON 1-28 DONALD t't:U:HSON 8.2 2.0 1.34 2S M.CANYON 1-28 DONALD PEJ"ERSON 36 M.CANYON 1-213 DONALD t't:1 t:t1SON 5.0 7.0 0.07 37 M.CANYON 1-28 DONALD PETERSON 41 M.CANYON 1-28 DONALD PETERSON 2.6 1.2 0.07 44 M.CANYON 1-28 DONALD t't: I t:HSON 4.0 1.5 0.08 47 M.CANYON 1-28 DONALD PETERSON 15.4 7.1 55.86 60 M.CANYON 1-28 DONALO PETæSON 100 M.CANYON 1-28 DONALD PETERSON 10 M.CANYCN #1-8 RUSCH 19.5 20.0 573.49 20 M.CANYCN #1-8 RUSCH Z2..7 23.0 139.27 21 M.CANYON #1-8 RUSCH 21.2 19.0 68.58 GMC Data Report No. 206 10/34 Figure 10. Four different types of plots based on the data taken from all samples. The graphs at the top of the pages represent lab-derived data, whereas, the graphs at the bottom of the pages represent well- log derived data. GMC Data Report No. 206 Correlation coefficients are as follows: A. R = 0.88 B. R = 0.92 C. R = 0.80 D. R = 0.64 E. F. G. H. Power function equation is on the graph. Power function equation is on the graph. R = 0.50 R = 0.45 11/34 A 8 ~ ... 0 ü . 10&. '; .. 0 a: ë u.. " ., ~ .. 41 Q CD 0 ~ ü := GMC Data Report No. 206 1 ??oo:- l - ~ ... o Ü ~ 1000 1:- ~ . ãi QJ a: é u.. " o ~ ... u Q ..a ~ 1??oo - - " , ,- ß , ... . , I L { JA f !. j ¡ T J I ¡Log F "': 1.57 (Phi) ~ 3.76 t Porosity vs Fm. Resistivity Factor All Samples '" ) ......... -~' ., . t . ,. -- . r , , ' I -. . -. oX ,. 100 , ~' ..., I ~¡ 10· , .. " , ..;,. ' - , , 1 1 10 Lab Derived Poroafty. Phi, (%) c:J Charles Saft + Ouperow . Mission Canyon Â Phosphoria x Wahoo Porosity vs Fm Resistivity Factor All Samples I - ~ " . 100 ~~.' l' '-í 1000 · , ~ \ I ~ ~ ~ i . . ¡Log F ~ · 1.~ (P~i) ~.~ t: 100 .. -f~+ ,)( ,o~ - ¡ 1 1 ,'Q Wen Log Derived Porosity, Phi, (%) ::: Charles Salt ... Ouperow . Mission Canyon Â Phosphoria x Wahoo , f I f , t 1 1 . ~ . , , 100 12/34 C :a- e - .;¡¡:" ~ :a · 0 E ... v Q. '- ;¡ " ~ ... :: · · v :: D =ã .§. jI," ~ :ë .. u e ... u C. ... ;( " u ... :: at a CII :¡ I ." -....-- .. - .. .. t -.ß:'Y'I'VRP;-:.a "..~l"."V- I 1 Porosity vs Permeability All Samples 10??oo ~ -. . .~ !Log it = 0.16 (PhI) -1.48 tl I· ¡ I · 1- .., ..~ 10 . I A __ ' ~ ----: - ....~ - .. .. . ...... . \. h___....J~i.- _ -I i . 'M~ . · o::~~r--~·-: o 5 10 1S 20 lab O.rtved Parody, PhI, (%) 1 ??oo 1000 ' I . ~ I ~--1 ·_,.,."-fl.'....:_A,__~ " :t ,~'y , I,.., 100, ,. .. I '25 c:J Charles Salt .... Ouperow . Mission CðJtYon ... Phosphoria x Wahoo Porosity vs Permeability All Samples 10??oo , ... ;.)0, . _\ _ ".._."..".^. \~, .~.., 10000~ Lag k :8 0.13 (phI) · 1.21 J. 100011 t ~ 100.1 ..'" . ...../... .'m..L..... ... _n , I 10' . 1J . I ~ I ,. ........_._...._~ 1-.,'" h... ._..~~4. .l.~ -í: ~~ .~J...:~ - x-I x, - - .A[ ~i. -r £~ ~u . I ¡ 5 10 15 20 2S WeJl Log Oerived Porosity, Phi, (%) . I- - . I I 0.' I 0.01 I o C Char1es Salt "1'" Ouperow . Mission Canyon .. Phosphoria x Wahoo GMC Data Report No. 206 "¡/' <f .' I ..N' ,',"'..j _ - I .. .\,. f tun. ......._... _.L.J. ...,..~ .... ...1 I 30 35 ¡ -- ... I 30 ¡ 1 I 3S 13/34 4 E 3.5 J E 2.S 'a · ~ 2 ... · Q ..ca 1. 5 · ..a 0.5 0 0 " F 3.5 e 3 'a 2., , . ~ ... . 2 Q ca 0 '.5 ..a .. 3: , 0.5 O· 0 GMC Data Report No. 206 Porosity vs Cementation Exponent All Samptes I I I ,. I .,.. ~ .~ . - ~ ~ - .Â.~ x _ ~-...::. .. tOp I Y 4 .... I I I t I , I I I I I t I ,m. (Phi ~o.120) -1.671 r- - I I 5 1S 20 Lab Oerived Potaalty, PhI, (ex.) 10 C Chartes Satt ... Ouperow . Missjan c.nyon Â Phosphoria I I I. I I 2S 30 3S x Wahoo Porosity vs Cementation Exponent All Samptes I I I I I I I m - ( Phi" 0.092 ) · 1.78S t--- , t I I I I I I I ~À~t ......... ~ -w< x ~ I I I f I __ _I .1 .... ...1':-·· I~ -)( - I T 5 1'0 Ù3 2.0 2S WeU Log Derived Poroatty, Phi, (%} - Charles Salt Ouperow . Mission Canyon Â Phosphoria I I I. I I ~ JS x Wahoo 14/34 15/34 x Wahoo c: Char1es SaJt ~ Duperow . Mission Canyon .Â Phosphoria 1 3., l 2.9 l 2.7 ¡ ~ I 2..S We" L.ov Derived "' i.. ~ . ,) t 10l..._ . I 1~ o.1~ 0.01 l 1.5 ~. I . ~ - , I ~ ~ -L.... $r f~· ~. ~ ___ - ^.À& ' _ · ; I I 1 :9 2. 1 i3 .~._.~ .. :i. . I I I I ü.- ,0??oo . ". dh. ,.l ~ ',': .,... . 10c00~ I.DII k. 2.%1 1m) -.u:s ,... 1000J.. I. I · J 100 f . I .. , ,; . Cementation Exponent vs Permeability All Samples x Wahoo C Chartes Salt + Cuperow . Mission Canyon Â p~ 1~ I.Dg k. 2.31 (ml-"'" I! ....m i____ L - .- 1 : .. 1000., i . I . !. III coJ.. 1 ¡¡I ,-.1 -' ¡ 10 ~- ...,!.'. - ~'" ;.,~ . -<::..I.",~..,¡tLv',..,- ~ ~~t~·~ i.~ ~f ..; ;1 _ ··1 I ! I ! r ! 1 1.1 1.9 2.1 2.3 2.! 2.7 2.9 LaDDenvedM 3.1 1~ o.1~ x 0.0,'1 1.~ ..... ,.-... ....__ _._ .iI.. 100cc0 ... . I, 1 ,I. ...,. Cementation Exponent vs Permeability All Samples GMC Data Report No. 206 H ~ !. .)fl.- ~ :ë · ., e ~ ., Q. ~ ;C ~ ., .. = .. · G ::E G =õ .§. ~ ~ :g · ., e .. ., Q. ... ;( ~ ca :; .. · ca :i Figure 11. Plots for samples containing predominantly vuggy porosity. The graphs at the'iop of the pages represent lab-derived data, whereas, the graphs at the bottom of the pages represent well-log derived data. GMC Data Report No. 206 Correlation coefficients are as follows: A. B. C. D. E. F. R = 0.80 R = 0.69 Power function equation is on the graph. Power function equation is on the graph. R = 0.75 R = 0.77 16/34 A ii E - .¥.- ~ ::ä II .. e ... Q a.. '- ;( "tI u '- ::I co II G :æ S =6' e - .¥.- ~ jS ca u e ... G a. "- < " .. ... ::I .. . CD :E Porosity vs Permeability VuggyPorosity Samples 1??oo I ... ... . .. L- . I 'OOO~ Lag k = 0.15 (Phl)-1.S7 r 'I L ...,.' .. J~ ~ ¡ l' ...' Ã .._.. __._._. .; -r L-L.. /A"' I - - .I. '";, ~ I ¡. ¡ ... -... 1 I S 10 15 20 Lab Derived Porosity, PhI, (%) . -lit 100 I " A/ 10 ,- .. 0.1 t· 0.01 o 25 I x Wahoo . Mission Canyon Â Phosphoria Porosity vs Permeability Vuggy Porosity Samples 1 ??oo w....,\., . 1000:)Lc9 k = 0.12 (phI) e1.16 1 . .. 100 10 1 . . ¡ ... ¡ k ~-- ) - ":1 --r I~~¡ Ã! ... I 11 t,Æ/ I- t , . Ix . a.1~ ~ t · 0.01 I ! o 5 . , ! 10 15 20 25 WeU Log DerIved Porosity, PhI. (%) I x Wahoo . Mission Canyon Â Phosphoria GMC Data Report No. 206 '" ,. ".,., """ - 1'1, .. ./ . . .~ 30 ~ I 3D ~. ,.. -.. ,.,-- , 35 35 17/34 c 3.:5 e 2.5 "a . ~ 2, . Q ~ 1.5 -J a.S· D 3.5 ~. GMC Data Report No. 206 Porosity vs Cementation Exponent Vuggy Porosity Samples "' I I 1t -~ I ... ~ I I I 3 o o 5 10 I x Wahoo I , I I I I I I I ! m.. (PhI-o.150): 1.5931- I J I I t I I !" 15 20 Lab aerived Porody, PhI, (%) -!II ·1 -. .. . ~ 3s * ...... ... . 30 . Mission ~ ... Phosphona .¡ .. .~ I . 1-:' Porosity vs Cementation Exponent Vuggy Porosity Samples "' o o I x Wahoo I I I I I t L m m (Ph.'" 0.116) -1.742 r-- I I 10 115 20 :is Wen Leg Oertved Porosity, Pht, (%) . 30 3S 3 ~ ,~~I I .... ~ ~.x '; 2 ._ o -J US I .. := I I 5 . Mission Canyon Â Phospnoria 18/34 1 ??OO. I E =õ 1rœJ !. .::.;,- 1001- ~ :E · Q E 10..- ... Q a.. ... < " I.... ., ... :: · 0.11 · Q ~ 0.01 1.S GMC Data Report No. 206 Cementation Exponent vs Permeability Vuggy Porosity Samples ...L..L ._~\_. ... II ¡ ~ -=- . ..-- L.og k= 3.43 (mþ-1..5S E I .,. ( 1'=__.__ L_____ ___ ~~ ._..~...- T.-J Å ~;¿x.l. - ~x .. ......,- ~.,...,..,. ..,..~.. .-. ,.., ., " Ie--: i . .. .. - .._-.. .... .. . ..-- I 2 I x Wahoo L.... .. . l.,......._.. .. .V ; ! ..-,..~"". . . 't' , I is 3 Lab Derived 1ft I , is . Mission Canyon ... Phosphoria Cementation Exponent vs Permeability Vuggy Porosity Samples [ x Wahoo , ..~.. -..- j , I 4 ; ¡¡I . ... I l_~~_k. ~(~) ·&71 5 -, - . ,.. /. I I . --...- -. .__1. 1 ??oo . . . " I 1 F =õ I I .'.5- 1000"- .....- .::.;," 1001 I ~ L :E · ¡ ¡ ., 10J Å E ;; )\. . \L a. ,1 ... :;( " Q ... :: ¡ .- .. 0.1 J Q :i I 0.01 , 1.5 I '.. .. 1 I is 3 Wen Log Derived I'll :is . Mission Cdr1Yon Â. Phoscnona . ". .....--.. , -.J 1 ¡ 19/34 Figure 12. Plots prepared based on the data taken from samples containing predominantly intercrystaHine porosity. All the graphs were made with only lab derived infonnation. The last graph is a comparison of the data from this study with the Shell- TTIJ data. Correlation coefficients are as follows: A. R =0.92 B. R = 0.87 C. Power function equation is on the graph. D. Power function equation is on the graph. GMC Data Report No. 206 20/34 A =õ g .;¡,:,- ~ :ä . .. e ... 4J Cl. ... ;( "0 .. ... := CIII . .. :2 1000 , Porosity vs Permeability IntercrystaUlne Porosity Samples ..' "v'·-··y'-·, ....""'. ... .,,\:, , ,..... __.0. .', .,.-. . -, -Y" , , 100::1 Log k ~ G.22{PhI)·1.51 . 10 0.1 . 0.01 1 1 ??oo ' B ~ ... o Ü III U. if!:' 1000 ~ -;; ¡; Q c: è u. 1 100' ~ ... Q Q ~ CI ~ GMC Data Report No. 206 , I ¡ ¡ . I I I .t= ~ Log F :a · 1.20 (PhI) + 3.33 I I I I r j _1 ~ ~ I -- ---. --- ~ --~.. ]II ..~ I· [ --,.,- - x~~YI x 3 5 7 9 11 Lab Derived Pcrosfty. PhI, (%) ( + Cuperow x Wahoo ïm Red River I Porosity vs Fm. Resistivity Factor IntercrystaJllne Porosity Samples -=' , , -~l :, I ~~~L! x ¡ ~~)( ., ~-- 10 1 I 10 Lab Derived Porosity, Phi, (%) - Duperow x Wahoo ~ Red River I , .., . v --. " 13 , , I I I I ¡ I I I I I 100 15 21/34 I t I ,m :Ir ( Phi ... Q.1:J8 ) · 1.554 t- I I II I I I I ÂÅ ~ I I A . I I I i m ~ ( Phi" 0.142 ) 9 1.432 f Porosity vs Cementation Exponent IntercrystajUne Porosity Sampfes .. C 3..5 3 e 2.S " · > ¡: 2- We ~ · x~ c X J:I v · 1..5 ...I x -+- ..... Q.S I ~ 7 9 Lab Oerfved Poroaäy, Phi, (%) 11 o 1 5 3 r ... Ouperow x Wahoo Z Red River Porosityvs Cementation Exponent IntercrystaUine Porosity Samples . I I I ........J.. u D i I ~J m =- (Phi" 0.136) 91.5541 I I 2..!' ~.~ .... . ....~ .~ Á,..... ~ Â..A Â ...... 1..5 ,/J¡þ. 'I.. . e 2' Q.S 0, 1 10 ,~ Porosity, Phi, (%) 4 " I · This Stuay Â Shea. TIU .... -+- 13 t 15 l' Zz GMC Data Report No. 206 22/34 Table 2. GMC Data Report No. 206 Porosity types in the samples are shown in percent. This data is from a 300~p'oint-count of the thin sections. 23/34 Sample Formâon Vuggy Por. Mictopor. Intercrystal ~ No NMIe (%) (%) Por.(%) Por.(%) 7 Q\8lIee Salt 71 0 29 0 8 O\ariee Salt 38 4 59 0 49 ChariM S8ft 51 17 31 0 87 Q\ariee Salt 98 0 2 0 88 018riee Salt 32 10 58 0 89 Chariee Salt 70 0 30 0 6 Duperow 35 0 58 7 11 Duperow 4 0 96 0 13 Duperow 15 0 80 5 14 Duperow 16 0 84 0 4S Ouperow 58 0 24 18 51 Ouperow 54 0 38 8 61 Ouperow 58 0 38 4 90 Duperow 34 0 56 10 91 Ou, !row 33 0 60 7 92 Duperow 33 0 67 0 93 Ouperow 34 0 64 2 62 Wehoo sa 42 0 0 63 Wehoo 99 0 0 &4 Wehoo 98 0 65 Wahoo 12 88 0 0 66 Wahoo 4S 30 2S 0 ãl Wehoo 0 18 82 0 68 Wahoo 0 100 0 0 69 Wahoo 96 4 0 0 70 Wahoo 0 97 3 0 71 Wahoo 8 2 90 0 72 Wahoo 80 3 17 0 73 Wahoo 5 2 93 0 74 Wahoo 6 93 0 ~ Wahoo 55 6 39 0 24 M. Canyon 91 7 0 2 22 M. Canyon 67 33 0 0 2 M.Canyon 74 26 0 0 2S M. Canyon 88 8 0 4 41 M. Canyon Z1 73 0 0 60 M. Canyon 97 2 0 9 M. Canyon 23 65 0 12 GMC Data Report No. 206 24/34 Figure 13. Ternary plots based on the porosity types provided from point counting of thin sections for all fonnations. A. Porosity and penneability values for each sample. B. Porosity and cementation exponent (m) values for each sample. GMC Data Report No. 206 25/34 IlL...... VUGGY POROSIlY (0/0) Permt".:\bililY (md\ Porosity (%) a..aa. . , jJf ~ .'/ // " I)IJI Q...U - ~ 7 MICROPOROSfTY (%) ~ , ~ 1 . INTERCRYST AlllNE POROSITY (%) WAHOO FORMATION VUGGY POROSITY (%) Cemenr"rion E'\Ponent (m\.. 2..3Q. 17 'T Porosity (%) . ZJ.3. , ~-... 7 MICROPOROSfTY (%) Ul 1 . 3 lNTERCRYST ALLINE POROSITY (%) WAHOO FORMATION GMC Data Report No. 206 26/34 Wahoo Formation: The Wahoo Formation, unlike the other fonnarions shows more scattering on the ternary diagrams. There is no predominant porosity type (vuggy, intercrystalline, and microporosity), but rather the data points are disnibuted among the three poles. Most of the high penneability values are located in the vuggy porosity comer. The cementation exponent data are concentrated near the poles. Çharles Salt Formation: - . The Charles Salt Formation is composed of a combination of vuggy and intercrystalline porosities. The plot shows a trend of higher penneability with higher vuggy porosity percentage. A similar trend can be seen in the cementation exponent toward vuggy porosity. Duperow Formation: The Duperow Fonnation consists predominantly of intercrystalline porosity with lesser amounts of vuggy porosity. With some exceptions, penneability values appear to increase with increasing vuggy porosity (more data is needed to document this relationship). Although the two highest cementation exponents are located closer to the vuggy porosity comer, there is not a clear trend in any direction. This might be due to the presence of channel porosity which probably lowered val ues of the cementation exponents. Mission Canyon FonnatiQn: The data points for the Mission Canyon Formation are clustered between vuggy and microporosity, but closer to the vuggy porosity corner. Except for a few data points. penneability values. overall. tend to be higher with increasing 70 27/34 GMC Data Report No. 206 vuggy porosity. The cementation exponents also tend to have higher values with increasing percentages of vuggy porosity. Red River Fonnation: Red River Fonnation is characterized by a combination of vuggy and intercrystalline porosities with minor amounts of microporosity. The permeability values are randomly distributed. This random distribution can be seen in the cementation exponents as well. Cementation exponents are generally less than 2.0. Phosphoria FOJ'111ation: The Phosphoria samples are clearly dominated by vuggy porosity. It is difficult to see any meaningful distribution in permeability values or cementation exponents. However, the cementation exponents are generally greater than 2.0. niarenesis: This section describes the diagenetic history of each of the formations I studied. One of the main purposes of this study is to determine the impact of diagenesis upon the pore geometry. For example, dissolution can either create pores or enlarge existing pores. whereas, cementation can destroy or modify the pore geometry. Wahoo Formation: The samples of the Wahoo Fonnation used in this study can be divided into two groups. The first group is characterized by dolomitized mudstone, and biosparite (bryozoans, echinoids, brachiopods). The second group is GMC Data Report No. 206 71 28/34 pervasively dolomitized and is represented by mosaic or interJocking coarse dolomite crystals. Their paragenetic sequences differ slightly, however, there is a common paragenesis for the two groups: 1. Deposition of the original sediments. 2. Dissolution: minor for the first group of rocks, however, the second group of samples have undergone intensive dissolution creating vuggy porosi ty . 3. Dolomitization: in the first group, dolomitization is cryptocrystalline. The second class of rocks underwent pervasive dolomitization which formed a mosaic of coarse interlocking dolomite crystals. The interlocking nature of the crystals greatly reduced the penneability of the rocks. 4. Silicification: both· carbonate grains and matrix underwent replacement by silica. 5. Cementation: precipitation of sparry calcite cement between carbonate grains in the first ,category samples greatly reduced their porosity and permeabil ity. 6. Fracturing: some fracturing took place in both groups. 7. Precipitation of sparry calcite in void spaces and fractures; mostly in the second group samples. Charles Salt Formation: The samples of Charles Salt Formation used in this study are characterized by sucrosic dolomite. Porosity is a combination of both intercrystalline and vuggy. The diagenetic history is as follows: GMC Data Report No. 206 72 29/34 DISCUSSION The cementation exponent of the core samples was detennined using a special technique. Môst of die relationships among the various petrophysical values are as expected. However, the relationship of the cementation exponent to permeability and cumulative hydrocarbon production was not as expected: the relationship between m and penneability did not give a positive best-fit, and the m versus production plot failed to show any meaningful relationship. A'1alytic~1 Technjques; Measurement of m in carbonate rocks containing vuggy porosity (especially those with open vugs on the surfaces of cores) requires a special core analysis technique (see methods section), unlike other carbonates and sandstones. Inaccurate measurements were produced when standard analytical techniques were applied to carbonate samples containing surface vugs. The open surface vugs do not hold the brine and therefore the weights of 100 percent brine saturated samples were not accurate. This caused the porosity and therefore the cementation exponent to be incorrect. Permeahilit}1 ~nd Porosity: The penneability and porosity data show a large range of values due to the heterogeneity of the carbonate fonnations studied. The combination of vuggy and channel porosities produced the highest penneability in the samples. This combination occurs in the Mission Canyon Formation, but not in the other formations studied. The lowest permeability values are observed in the Wahoo and Red River Fonnations1 and result from the tightly interlocking dolomite- crystal fabric (Fig. 14) and anhydrite occluding void spaces in these rocks. 77 30/34 GMC Data Report No. 206 the cementation exponents are not high enough to be effective. In other words, the pore path (tortuosity) is not complex enough to influence permeability and production. In order for m to affect water saturation or hydrocarbon production. it must be at least 3 or over. This can be observed clearer in Figure 2. Also as mentioned in the results section, reservoir pressure, reservoir shape, and other parameters could affect the relationship between m and production. Petroprilphic Analysis: Diagenesis played a very significant role in forming the porosity types and rock textures of the formations. For example, vuggy porosity is a direct result of non-selective dissolution, whereas intercrystalline porosity is due to dolomitization. The predominant vuggy porosity in the Mission Canyon Formation produced relatively high cementation exponents. The Duperow Fonnation, which has mainly intercrystalline porosity, has cementation exponents around 2.0. Where there is great variation in porosity type, such as in the Wahoo Fonnation, cementation exponents show a broad range from 1.54 to 2.47. . 82 GMC Data Report No. 206 31/34 CONCLUSIONS The following conclusions were reached: 1. Oetennination of m in carbonate rocks is more complex than in sandstones and requires greater care and special core analysis techniques. For example., carbonate cores containing large openings or open vugs on their surfaces cannot be treated the same way as sandstones or erroneous values will be obtained. 2. The well log-derived formation evaluation data correlate strongly with the lab-derived results. This proves the utility of well logs (which are more economical than coring) in the determination of m. 3. The measured permeability data shows a broad range of values (0.04- 1501.31 md). This results from depositional and diagenetic heterogeneities in the carbonate formations studied. 4. Samples characterized by a combination of vuggy and channel porosity have high permeability, whereas those characterized by tightly interlocking dolomite crystals have low permeability. Pore- filling anhydrite can also reduce' permeability. 5. The cementation exponent decreases with decreasing porosity in low- porosity carbonates. 6. The correlation between porosity and penneability is almost identical 83 32/34 GMC Data Report No. 206 to the correlation between m and permeability. This indicates that porosity is the major factor affecting penneability whereas m does not show an effect on penneability. The cementadon exponent and penneability both show relationships with the surface area and other dimensions of void spaces. This relationship might not be strong enough because the flow of electrical current through water-filled capillaries in rocks is much more efficient than the flow of hydrocarbons through the same capillaries. 7. The expected relationship between the cementation exponent and production could not be established. This is probably due to the fact that the cementation exponents are below 3.0 and other variables could not be constrained (i.e., reservoir pressure, reservoir shape, etc.). The cementation exponent can affect both penneability and hydrocarbon production whenever it is over 3.0. GMC Data Report No. 206 84 33/34 Decline Curve-Usburne L2-26 Well Wahoo Formation 700 ~ 600 ::::; a:1 500 e. z - 0 en . ~ "C 400 e" C :J co C en :::J 0 0 300 a: .s:::. a.. C ~ a: 200 . < w > 100 0 .. J T 1985 1986 1987 1988 1989 YEAR Decline Curve-Usburne L5-24 Well Wahoo Formation 600 sao - ...J CD CJ - 400 z - 0 en § "0 c: ~ tU 300 c en ~ 0 0 a: J: a.. t::.. ~ 200 a: < w > 100 i ~ ¡ . . I o · 1986 1987 1988 YEAR I 1989 I 1990 93 34/34 GMC Data Report No. 206 ....