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Home My WebLink AboutGMC Data Report No. 232 Petrographic analysis and formation damage potential of core plugs (12,017' - 12,037') from the Husky NPR Operations Seabee Test Well No.1. Received 5 August 1994 Total of 9 pages in report Alaska Geologic Materials Center Data Report No. 232 1 I I PETROGRAPHIC ANAL YSIS AND FORMATION DAMAGE POTENTIAL OF CORE PLUGS, 12017-12037', HUSKY SEABEE #1, NORTH SLOPE, AK James 1. Hickey S93-o6 January, 1993 GMC Data Report No. 232 1/9 4 , ¡ I AReo Exploration and Produc, ,Technology <> Internal Correspondence - CONFIDENTIAL - DATE: January 15, 1993 I SUBJECT: Petrographic analysis and formation damage potential of core plugs, 12017-12037', Husky Seabee #1 (offset to Big Bend prospect), North Slope, AK 593-06 FROM: James J. Hickey PRC D3320 PHONE: 754-4155 TO: M. Werner ANO 720 K. Paige A TO 1286 F. Bergren ATO 1292 J. Trantham ATO 1408 I ' " I Thin sections (Plates 1-3) and X-ray diffraction analyses (Table 1) from three 1" plugs (12017-37') cut from conventional core in a zone of interest in the Husky Oil #1 Seabee (an offset analogue to a target of the Big Bend prospect, currently drilling) have been examined to identify potential formation damage mechanisms, as a screening tool for possible further fluid- flow testing, and to document controls on reservoir quality. The sandstones are generally only lightly-cemented with little clay matrix, but are silty, only moderately-sorted, strongly compacted with abundant ductile lithic grains: pores are scarce, small, and poorly-connected, and inferred permeabilities are quite low (air perms of a few millidarcies or less). XRD analysis indicates that chlorite and illite are the only clay phases present, and these occur in large part as lithic (sedimentary and metasedimentary) sand grains. Mobile fines and swelling clays do not present any significant potential for formation damage in such sands. These particular samples probably do not represent oil pay. As a result, critical rate tests have not been performed for these plugs. I I I r I I The sandstones are typically fine-grained, silty, clean to slightly shaly, moderatlely- sorted, closely-packed (low remnant intergranular volumes), and lightly-cemented by patchy siderite spar, incipient quartz overgrowths, pore-lining chlorite, and framboidal pyrite. Detrital composition is dominated by quartz (commonly quite angular) with common feldspars, detrital dolomite, and shaly/phyllitic rock fragments (usually slightly to moderately squashed). Good reservoir-quality rocks will be better-sorted and more quartzose than these (a function of depositional setting, and certainly within the realm of possiblity). Sandstones similar in texture and compositon to these samples are liable to be of poor to moderate reservoir quality at best. Formation-damage concems in such sands include mechanical stability (sand production from poorly-cemented beds, fonnation compressibility due to pressure depletion) and capillary blocking (lost kro due to filtrate flushing, slow and difficult to recover due to adverse capillary properties of small, poorly-connected pores). For the purposes of an initial production test, the relative permeability problems are the main concem. Mitigation strategies include low fluid-loss mud with minimum overbalance, minimum exposure time of the interval of interest to the mud column, high underbalance during perforating and high drawdowns during f1ow, use of a surfactant additive in the completion fluid to encourage flowback, prolonged flow periods, and hydraulic fracturing beyond the invaded zone (which would have the added advantage of offsetting the limited native permeability). Poor initial test results should be diagnosed in light of the probable character of this interval (if available, rotary SWC's would permit quick petrographic and core flow-test input to the well test evaluation). Please call if you would like to discuss these ~nS:::~~Jhe~\~:_\~c I James J. Hickey I I I cc: D. Underdown PRC 03224 GMC Data Report No. 232 AR38 ·--4139 2/9 ] ] J ~ ] 11 ~ TABLE 1. XRD ANALYSIS HUSKY #1 SEABEE NORTH SLOPE, AK ] SAMPLE DEPTH 12017' 12031' 12037' WHOLE ROCK MINERALOGY I QUARTZ 58 55 63 PLAGIOCLASE 20 16 20 K-FELDSP AR 4 3 4 FE-DOLOMITE 2 1 1 DOLOMITE 2 3 3 SIDERITE 1 2 TR PYRITE 0 0 TR TOTAL SHEET SILICATES 14 19 9 TOTAL 101 99 "lOO SHEET SILICATES (CLAYS. + MICAS) ILLITE & MICA 30 36 18 CHLORITE 70 64 82 KAOLINITE 0 0 0 TOTAL 100 100 100 :1 ~I All values are weight %, normalized to total dry rock (whole rock mineralogy) or to clay-mineral fraction only (sheet silicates). TR = trace amount «1 %). Totals other than 100% are due to rounding errors. Analysis by J. Genuise (754-6098). GMC Data Report No. 232 3/9 12017' Husky Seabee # I PLATE 1 SANDSTONE, very fine to fine-grained, silty, moderately to moderately well-sorted, close- packed with little intergranular volume, moderate planar fabric, only minor detrital clay matrix. Llghtly~cemented by small patches of carbonate spar, traces of incipient quartz overgrowths, small pyrite framboids, and pore-lining chlorite. Angular quartz grains common. Scattered small « 20 microns) intergranular pores and subordinate isolated intragranular pores. Detrital grains derived from metamorphic and carbonate terranes: monocrystaJline and polycrystalline quartz, plagioclase (fresh, albite-twinned), K-feldspar (albitized?), mica (muscovite, chlorite, biotite), detrital carbonate (dolomite spar, micritic fragments). argillaceous sedimentary and metasedimentary rock fragmehts (common), tourmaline. Shaly/phyllitic rock fragments are slightly to moderately squashed, occasionally microporous and/or altered to kaolinite. XRD mineraloQyestimates: 58% quartz, 24% feldspars, 4% carbonate, 14% clays + mica (chlorite> illite/mica) DESCRIPTION Strongly-compacted, poorly-cemented, silty very fine to fine-grained sandstone with common argillaceous. lithic fragments (brownish grains) and rare, isolated macropores (AS, F5). Close-up of silty sandstone with incipient quartz overgrowths between grains and small remnant intergranular pores (C5, E3, E6t G7), commonly with thin linings of authigenic chlorite. Note argillaceous rock fragment (F5) and scattered detrital carbonate crystals (E4, F4. 11). A pore system such as this is liable to exhibit a very high irreducible water saturation, poor relative oil permeability, high entry pressure for drainage, .and a propensity for damage by capillary blocking due to filtrate invasion. S . -1 ¡ _ 1 ' - ,- !.. : o ¡' 'r" -,\. ,. ; ; .'!~ I i .. . . - r I ,i -.-..-------, i- " -- "e~":" -, ' I' c" ~ -c: ~ . J ,.. ,- - .c( .-~ -:(' '" ,- ~-~ ~-~ f-·~f,.'-~- ~-7-C-:~,=_=_:~--== --/-- , ,-- __- ¡' I ~-- - -' ~ i -.\, ..! 1---: .......... ¡ I 'f- , I r I ": 1 -,~ :- :-~ i ' ---- II' ·)1 ,'~ - " .,.-... . , -..c;::: -,---I "J" -:. 'þ -; , I - '. ' "/'~~ ' . . - . f' -. - -'--.- PHOTO A 8 " , ¡ " t- :yl I " - :¿ ( ~ I. --..' -<: I , 1. - ; f ! ~ ! r , ~, I , ( 1 I· - I i ¡ I ~ j I ~ ~ L¿ I?·. ~ -1 I .4_ ~ 1- ~, s- ¡ '. ~ \ ~ ./ G~C .¡J~t' Reltn1 NfJ. 2þ2. ; I J" r , - I I ·1,- ~.:' +--~- f ". '-J.-t - . ... -, ! - - "J t - I ; , .'''; .. l ; _ t -+- - I ~ ! 1· -t t 1-' , t -: :. '~I ! , : : L~ -. ,¡ : : 1- 'I , t- r i' -I -I :-' t' . t - ¡ ~ 1 ' _ ': : ~ t ¡ ~ ....l- I t -, ""'- , .. ~ : I' - . j -- , , .', - - I t 1- ~·-i' I :- "I . '-:-1 ¡ '_, ¡.' - ~, L-r 1 - f 1 1 ! ~ . -.. ~ _J_ " ¡ ï i ¡ ! - ; ¡ . ; I ¡ I :1 ( <' c-~ ~- .--1 .. m. , I . t ' . ~ . . - I' ! ¡--- j - !:' . , - I I I 1 4/9 ~ ~ -J -T--- ,.... ,....... ~ I .... l A .1 12017' ] ~:1 ) J ] ] 11 : I B 12017' ~ I .1 A B c PLATE 1 IiUSKY #1 SFAR~~ NORTH SLOPE, AI( E F 1 2 3 4 5 6 7 1 250µ 5/9 GMC Data Report No. 23~> BOREHOLE TECHNOLOGY, PLANO, TEXAS PLA TE 2 Husky Seabee #1 . 12031 ' SANDSTONE, fine-grained (range very fine to medium), silty, slightly shaly, moderately-sorted, close-packed, strong planar fabric, with minor small (1 mm diameter) vertical burrows(?). Most grains subangular. Porosity consists of scattered, peony-connected small intergranular pores, isolated intragranular pores, and microporous argillaceous grains and matrix. Lightly-cemented by traces of incipient quartz overgrowths, microcrystalline pyrite, pore-lining chlorito, late siderite rtlombs. Similar metamorphirlcarbonate provenance as 12017': monocrystalline and polycrystalline quartz, ductile argillaceous sedimentary and metasedimentary rock fragments, detrital carbonate (some appears ferroan), feldspars (some leaching of plagioclase), muscovite, chlorite, mafic volcanic fragments (microporous), zjrcon, sphene, carbonaceous organic debris (pyritized). Burrows(?) are enriched in coarser quartz sand (argillaceous matri)( and grains have been excluded) and extensively-cemented by quartz overgrowths (with some large late carbonate rhombs). ~RQ mineraloQV estimates: 55% quartz, 19% feldspars, 7% carbonate, 19% clays + mica (chlorite> illite/mica) ~', 1\' 'J ~-~ f "' ~ . ,- }" J~ ( , (~~ : ¡? { f -. ,: ( , GMC Data ~<p~rt ~o. ~ , ~ " I~' "' PHOTO A B \ DESCRIPT10N Silty, well-compacted, lithic-rich sandstone (84, K4) punctuated by a small burrow(?), D1-H7, that is much more quartzose and extensively cemented by quartz overgrowths. Dark. grains are argillaceous lithic fragments (sedimentary and metasedimentary). Macropores are rare and isolated. Closely-packed, slightly shaly sandstone with minor intergranular microporosity and isolated intragranular pores (C4, partially-leached plagioclase) and microporous rock fragments (basaltic volcanic clast at K7). Porosity and permeability of this sandstone are quite low. I ~' ~! l' Ñ '" .: ,¡ ·1: ~ '.~ - ~-¡ ~ . 8 . ~ .'¡:~, :.t,. -, '.. ~', i .1 6~,;:. - ,. Q i· 1;.", I' r ' i L ' . { " ' '. - ~ ..:....., -; , f· . I '.,. ~ ~ f _:. _ " ,.. ~. i \,1..'",-...., .......-...--.-....-.----...........-----...--..--~.. ..--....- 'r ','...:.. \. r r' ': - j' i -'------- r. .1,. ',' I. .---, I ;.~ -, I. ..1;- . --- ¡ :', ' r i - (, . ; l' : .- , ì I, r~, ',;¡-: t,;. - : ~ ---:-:=--=~~ ~~11 . -; ,,','. ~ ~ -,' . ,t ~-- " '~ ~ ,':" ~ 'i~f -; _,' : : - - I -. ' .. ,_. , ;.._~-. t·' .....-!-- ..: : :' ,,_+ '~~'.~=:- __i__ ~. 1..j, r :-¡ .1 ,~..:r ~í I )'f î~ --.- . ~ f -~ --..-..- ---- \- 1 ~ __---_ ~ ~ ! 1 t J ,'~_ . ~\ f } ~ ! I -4 " ~ - , '11 ¡ t .¡ ! I ¡ ~ " , , 1 I I - . "1' ~ -~1 ~: I ~-- ~.... \ ~ - _! ' ' -: I \ ~ !', r " ,-! ~ ~ ~ : L~ - -. 1 : : J t- r . j ~ --: 1', 1- -T ,17 1 ¡¡ i;. ¡ , " D. t --, .~ . f.~¡¡-I ' :- J . I, ! )'.. I . 1 1 1 ¡ t ~ l ! r' ~ ¡ r- ¡ - ! Î : _ _ _ ____.' ____-' __L-.._ __1_ . _ _ ._.___ -----.. .--...- . . - ¡ , , 1 I ! ' I . , i I I'--~ . -!:-¡- : 1 Î6/Ç . ~ 7/9 GMC Data Rep()°ÐBÅEHOLE TECHNOLOGY, PLANO, TEXAS 250µ . 7 6 5 )31' 4 B 3 2 1 2031 ' A 1 PLA TE 3 12037' Husky Seabee #1 XRD mineraloQY estimate~: 63% quartz, 24% feldspars, 4% carbonate, 9% clays + mica (chlorite » illite/mica) SANDSTONE, very fine to fine-grained (occasionally to medium), slightly silty, slightly shaly, moderately well-sorted, close-packed: faintly/diffusely-bedded, poor to moderate planar fabric. Slightly coarser, better-sorted, better-cemented (quartz) than 12017' and 12031 '. Light to moderate patchy (0.5-1 mm) cementation by quartz overgrowths, spany carbonate, large pyrite framboids and aggregates: traces of pore-lining chlorite. Common dead oil as thin interstitial films. Metamorphic/carbonate provenance: monocrystalline and polycrystalline quartz" argillaceous sedimentary and metasedimentary rock fragments (ductile, micaceous), detrital carbonate, plagioctase (mostly fresh, albite-twinned), K-feldspar (albitized?), chert, tourmaline. PHOTO A B t I , ì , I DESCRIPTION Lightly-cemented but strongly-compacted lithic--rich (common dark argillaceous grains) sandstone with scattered interstitial coatings of dead oil but no visible macroporosity. r Close-up of tightly-packed sand grains with incipient quartz overgrowths and black wisps of dead oil lining many grain contacts. If oil charging post-dates most of the compaction visible here, quite high capillary entry pressures (and thick oil columns) are implied by the presence of oil in such small pores in a tight sandstone. 'r-=;- t - _! J - ~.. -~ ~ 1 . . F. ~ ; -i:-' ; -, -¡ ¡ ~~- \ - !. _ r 'I ' "--', ; 1 -I'" .. - . ~... .'..; , . r 4 ~ t. , -' t- ~. 1 . - . f " -;:- ..: i ,#, ; ~.;. , - I·, - ·f ~ - ;"':'-';' ~ -L --== r--:--:-;--=·- Ir- . I ' í . ; " j : :.¡~' - -...1 i~ ~ ¡ Or, r i i . r.. ; -¡-' I... ¡ : )1 . f .~. ! :, - -¡- t-· . . r~~ - _ '_ f- .. . I I ~= I +- ~ - ~-. r ~ '. ~ ---.. -- -t" I , .... - . - , ~ - , '1 . ~ t r; - ~ I J.- I ~._' I .. ¡ ,- : ~' : t - ¡. ~ . ; ,-~. ~.;;. ~ . ; L~ - 1 ! : ¡ ,t- r~ i . ; T,'·,J' j~ I ~,+, .. i ::-- ~ l' · .,.... -:-1 . I . r ., j . t Ñ': I g. { 0 I· i , , ~'. ; '} I, ~ ~} ~. ~ .1 f' '-, :?: 1 S.----:, -, "\ i -. ~ .~, \ Gf'~C Jat~ ~or~ NQ. "'ß7 I , ','¡{ , - 1 ' , l' . ! . . I t.. t I. t . I i . ! , ... - , 1 ~ . . i ,- :1· .-. " ¡ . ¡ - - . 1- '!~~ ¡ I , I j f r ~ ~ I I ~ ( . --::--. .~; -~--=-----.:~ ~ a: , 1 <. ,- ¡.:-==~==--~~'".:1' - -' -. .., :~- ;(. ·~1 ,/ r' f t ~ r C~~I ~~ ~; ._ s .....-.- ¡ . I l'f ¡ II i . I f ! I I ! r 1, ì . , . j. .--- I . h ~ A PLATE 3 HjJ~KY #1 SEAREI= NORTH SLOPE, AK E F 1 3 12037' 5 6 7 . 6 1 2 3 B 12037' 4 5 7 GMC Data Report No. 232 250µ ~~ BOREHOLE TECHNOLOGY, PLANO, TEXAS 9/9