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Home My WebLink AboutGMC Data Report No. 053C[ scANNING ELECTRON HICROGRAPHS OF SELECTED ' SAMPLES .FROM PALEOZOIC THROUGH TERTIARY SANDSTONES, NORTH SLOPE, ALASKA. ARCO *'KAVIK UNIT 13 ARCO 14. MIKKELSEN STATE EXXON ALASKA STATE A #1 i".'.! EXXON CANNING RIVER UNIT BLK. A EXXON 'DUCK ISLAND UNIT tl EXXON POINT..THOMSON UNIT #1 · .. FOREST KEHIK UNIT #1 HOBIL BELl UNIT #1 I4OBIL HIKKELSEN BAY STATE 13-9-19 f4OBIL 14EST STAINES STATE 18-9-23 ~ SOHIO CHALLENG£.*ISLAND #1 . · GMC D~ta Repor:t.':53C :': ~.'....- SCANNING ELECTRON HICROGRAPHS OF SELECTED SAMPLES FROM PALEOZOIC THROUGH TERTIARY SANDSTONES, NORTH SLOPE, ALASKA PREPARED BY M. D. WILSON ALASKA RESEARCH ASSOCIATES MARCH, 1984'~ UPPER LEFT EXXON Pt. Thomson #2, 10204', Colville Shale, 900X Only modest visible intergranular porosity is present in a sandstone cemented extensively by quartz overgrowths (top) and ductile deformation (center). UPPER RIGHT EXXON Pt. Thomson #2, 10204', Colvtlle Shale, 1500X A cluster of authtgenic kaolinite books occurs above well-developed quartz overgrowths. LOWER LEFT EXXON Pt. Thomson #2, 10204', Colville Shale, 1200X A partially dissolved argillaceous chert grain occurs in-the center of the micrograph and a cluster of authigenic kaolinite at the top. Such intragranular porosity contributes only slightly to the total porosity. LOWER RIGHT EXXON Pt. Thomson #2, 10620', Colville Shale, 200X Relatively low tntergranular porosity is present. The major mechanism of porosity loss is ductile deformation along with minor quartz overgrowths. l:he .~or 'i~ ! L. ~ ' -. -~ '. i I UPPER LEFT EXXON Pt. Thomson #2, 10620', Colville Shale, 1800X Intergranular porosity has been destroyed by quartz overgrowths on which clusters of authigenic kaolinite books Occur. UPPER RIGHT EXXON Pt. Thomson f2, 11736', Colvtlle Shale, lO00X A siderite rhomb (center) and authtgentc kaolinite (lower right) plug the center of a pore primarily filled by quartz overgrowths (upper right). LOWER LEFT EXXON Pt. Thomson #2, 11736', Colville Shate 970X .................. Large quartz overgrowths occur on coarsely crystalline quar,tz while small overgrowths of diverse orientation occur on chert grains. LOWER RIGHT EXXON Pt. Thomson #2, 11774', Colville Shale, lOOX Large tntergranular pores are present in a relatively coarse sandstone. Clusters of authtgentc kaolinite books plug several of these pores. 1 ! , ! ! ! ! i / : · '4' · · I, t, · ¥ : I ! i . / / ! 1 -. , / / t / / / I f t I , UPPER LEFT EXXON Pt. Thomson #2, 11774', Colville Shale, 500X A well-formed quartz overgrowth plugs an intergranular pore. Small overgrowths of diverse orientation occur on the chert grain at the right. Authigenic kaolinite books are present at the upper left. UPPER RIGHT EXXON Pt. Thoalson ~2, 11774', Colv.i,11e ...Shale, 3300X Small quartz overgrowths with dtverse orientations are distributed on the surface of the chert grain shown in the previous micrograph. LOWER LEFT EXXON Pt. Thomson #2, 11774', Colville Shale, 2500X A cluster of authigenic kaolinite books plugs the Center of an intergranular pore. LOWER RIGHT .EX. iXON Pt. Thomson #2, .i.13:~24', ThoBIsOfl Sand, .500X Intergranular porosity has been destroyed by very extensive deformation of ductile micas and micaceous schist grains. UPPER LEFT EXXON Pt. Thomson #2, 13124', Thomson Sand IO00X A detrital dolomite grain occurs on the right and a ductile mica grain on the left. A quartz overgrowth plugs the pore at the top. UPPER RIGHT FOREST Kemik #1, 4610-20' Kemtk Ss. 400X Sparse moderate-sized tntergranular pores are still present in a sandstone cemented extensively by quartz overgrowths. Micropores occur in the partially dissolved chert grain at the center. LOWER LEFT FOREST Kemik #1, 4610-20', Kemik Ss. 500X A phosphate grain containing very small micropores is surrounded by quartz overgrowths. A partially dissolved chert occurs at the upper left. LOWER RIGHT .FOREST Kemik #1., .46]..0.-.Z0', Ke~ik Ss., 3000X Stacks and fans of chlorite platelets plug the center of an t ntergranular pore. Such clays are common but not present in large amounts in this sample. ~.. - ,,;. ; ..,,' 't.I UF' E×.- UP! FO~ LC FC L.. F UPPER LEFT FOREST Kemik #1, 4610-20', Kemik Ss. 200X Minor amounts of moderate-sized intergranular pores are partially occluded by quartz overgrowths. A few partially dissolved chert grains with micropores also are present (center). UPPER RIGHT MOBIL Beli #1, 11836', Ivishak Ss., 700X 1111ttc clays cover Well-developed quartz overgrowths. The clays exhtbit a curled flake morphology wtth elongate spines projecting from the edges. LOWER LEFT MOBIL Beli #1, 11836', Ivishak Ss., 2500X I11Jtized kaolinite (book morphology) in the center of an intergranular pore. Kevex analysis indicates these clays contain high, silicon, minor aluminum and very minor potassi urn. · LOWER R[GflT HOBIL Bell #1, 11836',. IvJshak .Ss...: .45.00X A. cluster of unt111ttzed kaolinite books occurs tn the of 'the mtcrograph surrounded by t11tttc clays (top and bottom). ~e ~qter UPPER LEFT MOBIL Bell #1, 11836', Ivishak Ss., 5000X Books of kaolinite (Kevex analysis indicates only high silicon and aluminum) plug the center of a pore. UPPER RIGHT MOBIL Bell #1, 11836', Ivishak Ss., $OOX Only sparse large-and moderate-sized tntergranular pores are present in a sandstone cemented extensively by quartz overgrowths. LOWER LEFT MOBIL Bell #1, 11836', Ivishak Ss., IO00X Quartz overgrov~chs extend to the center of an intergranular pore and have completely surrounded a cluster of authigenic kaolinite (center). LOWER RIGHT MOBIL Bell #1, 11836', Ivishak Ss., 3300X Curled flakes of tlltte from which long spines project over a small quartz overgrowth. UPPER LEFT MOBIL Bell #1, 11836', Ivishak Ss., 4000X Small rhombs of iron-rich dolomite (Kevex indicates high iron, minor to moderate magnesium and a trace of calcium) plug the center of a pore. UPPER RIGHT MOBIL Mikkelsen Bay State ~13-g-lg, 10618-1g' Colville Ss., 250X Large tntergranular pores are present in a sandstone cemented primarily by .quartz overgrowths. Kaolinite books occur in the center of some pores. LOWER LEFT MOBIL Mikkelsen Bay State #13-9-19, 10618-19', Colville Ss., 1500X A cluster of authigenic kaolinite books plugs the center of a pore. These books are partially enclosed in the outer portion of the adjacent quartz overgrowths. LOWER RIGHT grain at the upper left. MOBIL Mtkkelsen Bay State #13-9-19, 10618-19', C61ville Ss., 750X. Large"quartz overgrowths (t~p and bottom) p.arttally occlude a~n.:: tntergranular pore. ~11 overgro~,rths are present on the che~ ZSOX -~nted ~n 1500X of a ~rti on .o 7SOX Jde an chert UPPER LEFT MOBIL Mikkelsen Bay State ~13-9-19, 11697-98', Thomson Sand, 1300X A cluster of authigenic kaolinite books occurs in the center of a pore and are surrounded by large quartz overgrowths. UPPER RIGHT MOBIL Mikkelsen Bay State ~13-9-19, 11697-98', Thomson Sand, 500X Modest amounts of intergranular pores are present in a sandstone with extensive quartz overgrowth developmeent and a few patches of authigenic kaolinite books (center). LOWER LEFT MOBIL W. Staines #18-9-23, 7754-55', Sagavanirktok Fm., 800X Extensive ductile deformation of micas and micaceous schist fragments has destroyed the bulk of the intergranular porosity. LOWER RIGHT MOBIL W Staines #18-9-23, 12559-60' Colville Shale, 1300X Zeoltte has replaced a glass shard (smooth surface) t'n a tuffaceous deposit. A Kevex pattern indicates high silicon, moderate aluminum, minor (but unusually high sodium) and a trace of calcium. UP MO:.- UP~ MO~. LOS MOB. · · LOX';. MOB' UPPER LEFT SOHIO Challen~le Island #1, 13444', Thomson Sand, 150X Large intergranular pores are common in a sandstone containing abundant detrital dolomite. Quartz overgrowths occlude a minor amount of the pore space. UPPER RIGHT SOHIO Challenge Island #1, 13444', Thomson Sand, 200X Oetrital dolomite grains occur at the bottom and quartz grains with overgrowths at the top. Note the large intergranular pores. LOWER LEFT SOHIO Challenge Island ~1, 13444', Thomson Sand, 900X .. Rhomb-shaped projections on the surface of this dolomite grain may represent either overgrowth projections or solution facets. LOWER RIGHT SOHIO Challenge Island #1, 1344g', Thomson Sand, 150X Large tntergranular pores are present in a sandstone containing abundant detrttal dolomite., Quartz overgrowths partially occlude a few pores. ng tS. UPPER LEFT SOHIO Challenge Island #1, 13449', Thomson Sand, 300X A detrital dolomite fragment (center) has been partially dissolved. Such porosity does not contribute significantly to the total porosity. Quartz overgrowths are present on grains at the top center and bottom of the micrograph. Note the large intergranular pores at right and left. · oO This series of scanning electron micrographs were taken during an evaluation of sandstone reservoir quality conducted by Alaska Research Associates in the latter part of-1983 and early part of 1984. Samples for analysis were selected by Dr. ~1. D. Wilson. All of the analyses were performed by Dr. Wilson. The objectives of the analysis were the documentation of the pore network properties and/or evaluation of the types, abundances and sequence of development of pore-filling agents. All of the SEM analyses were conducted using a Hitachi F450 scanning electron microscope at AGAT Consultants, Ltd. in Calgary, Alberta. All samples consisted of small core chips mounted on aluminum stubs and coated with a thin film of gold. Micrographs were taken with a 35nm~ camera back attached to a port on the SEM console. ~lagnifications are indicated by a scale bar and value in micrometers at the lower right on each micrograph. Wells' depths and stratigraphic unit designations for each sample used in the study are listed below. Wel 1 Name Depth ARCO Kavik Unit ~3 ARCO W. Ntkkelsen #1 EXXON Alaska State ~A-1 EXXON Canning River ~A-1 EXXON Duck Island #1 EXXON Pt. Thomson ~1 EXXON Pt. Thomson Unit #2 FOREST Kemik #1 ltOBIL Bell #1 MOBIL Iqikkelsen Bay St. ~13-9-19 MOBIL W. Staines #18-9-23 SOHIO Challenge Island #1 Stratigraphic Unit · 5430' Ivishak Ss. 11250' Thomson Sand 10737' Colville Sh. 4882-83' Ivi shak Ss. 11874' Kekiktuk Cgl. 11899' Kekiktuk Cgl. 12160' Colville Sh. 10204' Colville Sh. 10620' Colvil le Sh. 11736' Colville Sh. 11774' Colville Sh. 13124' Thomson Sand 4610-20' Kemik Ss. 11836' -Ivi shak Ss. 10618-19' Colville Sh. 11697-98' Thomson Sand 7754-55' Sagavani rktok Fm. 12559-60' Colville Shale 13444' Thomson Sand 13449' Thomson Sand UPPER LEFT ARCO Kavik Unit #3, 5430', Ivishak Sandstone, 300X Only small intergranular pores remain following extensive quartz overgrowth development. Overgrowths on chert grains are absent or very small. UPPER RIGHT ARCO Kavik Unit #3, $430', Ivishak Sandstone, $OOX Intragranular micropores are common in a partially dissolved chert grain. Surrounding intergranular pores are plugged by quartz overgrowths. LOWER LEFT ARCO W. Mikkelsen #2, 11250', Colville Shale, 400X Extensive infill by detrital clays enhances pressure solution suturing. Note lack of large intergranular pores. LOWER RIGHT ARCO W. Mikkelsen #2, 11250', Colville Shale, IO00X Broken quartz grain (center) exhibits irregular outline due to extensive pressure solution suturing promoted by detrital clays at grain contacts. ~d UPPER LEFT EXXON Alaska State #A-l, 10737', Colville Shale 500X Extensive ductile deformation and quartz overgrowths have destroyed the bulk of the intergranular porosity. UPPER RIGHT EXXON Alaska State #A-l, 10737', Colville Shale SOOX Ductile deformation is the major mechanism of porosity loss in this portion of the sample. Note that micaceous grains have been molded around adjacent rigid grains. LOWER LEFT EXXON Canni.n~ River #A-l, 4882-83', Ivishak Ss., 700X Fans of chlorite are distributed throughout a partially dissolved rhomb of siderite. Quartz overgrowths project into adjacent intergranular pores but large pores still remain. LOWER RIGHT EXXON Canning River #A-l, 44)82-83', Ivishak Ss., 6000X Close-up of siderite rhomb shown in previous micrograph showing fans of fine-silt sized authigenic chlorite. UPPER LEFT EXXON Canning River #A-l, 4882-83' Ivishak Ss., 150X Tightly interlocking quartz overgrowths have eliminated most of the intergranular porosity. UPPER RIGHT EXXON Ouck Island #1, 11874', Kektktuk C91., lOOX Good visible tntergranular porosity is present in a sample cemented by quartz overgrowths. (;lusters of authigenic kaolinite books occur in a few pores. LOWER LEFT EXXON Duck Island #1, 11874', Kekiktuk Cgl., 2000X Close-up showing the well-developed pseudohexagonal outlines of kaolinite books plugging the center of an intergranular pore. LOWER RIGHT EXXON Duck Island #1, 11874', Kekiktuk Cill., 200X Limited quartz overgrowth cementation has allowed preservation of large tntergranular pores. UPPER LEFT EXXON Duck Island #1, 11899', Kekiktuk Cgl., IOOX Large intergranular pores are present in a sandstone cemented by moderate-sized quartz overgrowths. Kaolinite books plug some pores along the left edge of the mi crograph. UPPER RIGHT EXXON Duck Island #1, 11899', Kekiktuk C91., 400X Partially dissolved chert grains (center and center right) are bordered by quartz grains with large overgrowths. LOWER LEFT EXXON Pt. Thomson #1, 12160' Colville Shale, 1400X A mica has been ductilely deformed around a rigid grain (right) and has been partially altered to authigenic kaolinite books (center). LOWER RIGHT EXXON Pt. Thomson #1, 12160', Colville Shale, 250X Only very small amounts of visibl& porosity are present in a sandstone in which ductile deformation of micas and micaceous schi st fragments i s extensive.