Planningarea, Beringsea, Alaska
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OCS Report MMS 86-0033 GeologicReportfortheNortonBasin PlanningArea,BeringSea,Alaska Ronald F. Turner Gary C. Martin David E. Risley David A. Steffy Tabe 0. Flett Maurice B. Lynch edited by Ronald F. Turner UnitedStatesDepartment of the Interior Minerals Management Service Alaska OCS Region Anchorage,Alaska 1986 Any use of trade names is fordescriptive purposes only and doesnot constitute endorsement of these products by the Minerals Management Service. CONTENTS ~Page Introduction, byRonald F. Turner....................... 1 Part 1 Regionalgeology 1 Geologicframework,byGary C. Martin............... 5 2 Regionalgeologichistory, byDavid E. Risley ....... 10 3 Structuralgeology,by David E. Risley .............. 13 4 Biostratigraphy, byRonald F. Turner................ 27 5 Lithostratigraphy and seismicstratigraphy, by Gary C. Martin................................. 47 Part 2 Petroleum geology 6 Explorationhistory,byMaurice B. Lynch ............ 73 7 Reservoirrocks,by Gary C. Martin.................. 77 8 Organicgeochemistry,by Tabe 0. Flett.............. 91 9 Playconcepts,by Gary C. Martin, David E. Risley, RonaldF.Turner,andTabe 0. Flett............................................. 127 Part 3 Shallowgeology,geohazards,andenvironmental conditions 10Shallowgeology,by David A. Steffy ................. 135 11 Geohazards,by David A. Steffy andDavid E. Risley ... 145 12 Environmentalconditions,by David A. Steffy ........ 158 References.............................................. 161 Figures Figure 1 Location of NortonBasinplanningarea................. 2 2 Generalgeologic map ofeasternSiberia,BeringSea, and westernAlaska..................................... 3 LateCretaceoustoTertiarytectonic framework of theBeringStraitregion............................ 11 4 StructuralprovincesoftheNortonBasinregion ........ 14 5 Generalizedstratigraphiccrosssections across Norton Basin.................................... 16 6 Structurecontours(intime) on horizon A in NortonBasin........................................ 19 7 Structurecontours(indepth) on horizon A in NortonBasin.............................. 21 8 Contoursof Bouguer gravityoverthe Yukon Deltaand offree-airgravity overNortonBasin........ 24 iii Page 9 Relationship between free-air gravity value and depth tobasement...................................... 25 10 Stratigraphic and paleobathymetric summary of the COST No. 1 well................................. 28 11 Stratigraphic and paleobathymetric swmnary of theCOST No. 2 well................................. 29 12 Biostratigraphic correlation of the COST wells............................................. 45 13 Seismic profile, time-stratigraphic column, seismic sequences, lithology, and lithologic zones ofCOST No. 1 well............................... 50 14 Seismic profile, time-stratigraphic column, seismic sequences, lithology, and lithologic zones of COST No. 2 well............................... 51 15 Pattern of decrease in acoustic interval transit time and increasein bulk density for diatomaceous shales and their diagenetic equivalents, COST No. 1 well........................... 52 16 Pattern of decreasein acoustic interval transit time and increasein bulk density for diatomaceous shales and their diagenetic equivalents, COST No. 2 well........................... 53 17 Structure contours (in time)on horizon D in Norton Basin.............................. 57 18 Structure contours(in depth) on horizon D in Norton Basin.............................. 59 19 Comparison of large- and small-scale vertical wireline log patterns of rock unitTo-2, St. Lawrence subbasin, and characteristic vertical cycles of submarine fan turbiditefacies............... 63 20 Wireline log details of large- and small-scale bedding cycles of the inferred distal facies of a distributary mouth bar sandstone, To-3,zone COST No. 2 well........................................ 66 21 Locations of sale areas, leased blocks, and COST and exploratory wells............................. 74 22 Ternary diagrams showing the range of the principle sandstone framework constituents and the major rock types of lithic fragmentsin sandstones from conventional and sidewall core samples from theCOST No. 1 andNo. 2 wells............ 76 23 Plot of porosity versus permeability for conventional core3 (7,020.6 to 7,047.5 feet), COST No. 2 well........................................ 83 24 Distribution of sandstone porosity with depth,COST No. 1 and No. 2 wells................. 85 25 Water saturation determinations of a suspected oil zone at12,133 to 12,300 feet, COST No. 2 well..... 88 26 Chart of porosity versus irreducible water saturation for estimating permeability and determining bulk volume water for theCOST No. 2 well.............. 89 iv Page 27 Partial compilation of organic geochemistry from Norton Sound and the adjacentarea..................... 28 Organic carbon and classification of organic matter, COST No.1 well................................ 97 29 Modified Van Krevelen diagram, COST No.1 well......... 99 30 Indicators of thermal maturity, COST No.1 well........ 101 31 Classification of organic matter, COST No. 2 well... ........................................... 105 32 Modified Van Krevelen diagram, COST No. 2 well................................................... 107 33 Indicators of thermal maturity, COST No. 2 well................................................... 109 34 Hypothetical depositional history, tectonic history, and temperature gradient, plus selected indicatorsof thermal maturity, COST No. 2 well........................................ 113 35 Correlation of Ro and present dayTTI values, COST No. 2 well........................................ 119 36 Hydrocarbon generation model for oil and condensate from source rocks containing terrestrial organicmatter............................. 124 37 Possible structural and stratigraphic trap configurations associated with major Tertiary sedimentary sequences and pre-Tertiary basement...........~.................................... 126 38 Physiographic mapof the Bering Sea region............. 136 39 Bathymetric map of the Norton Sound planning area................................................... 139 40 Sea level history for the BeringSea................... 141 41 Isopach map of three Holocene sedimentary units in Norton Sound........................ .......... 142 42 Locations of epicenters of earthquakes................. 147 43 Surface and near-surface faultsin the Norton Basin planningarea.................................... 149 44 Map showing seafloor featuresin Norton Sound.......... 152 Tables Table 1 Wireline log analysis of the sandstone interval cut by core 3, COST No. 2 well......................... 80 2 Petrographic modal analysisof thin sections and core analysis of conventional core3, COST No. 2 well........................................ 81 V Page 3 Wireline log analysisof Oligocene sandstone sequence in the COST No. 2 well................................ 81 4 Depths and absolute ages of sediments in the COST No. 2 wellused in the Lopatin computation....... 112 5 Random mean vitrinite reflectance values for the oilgeneration zone................................... 115 6 Relationship of TTI values to hydrocarbon generation, COST No. 2 well....................................... 116 7 Maceral classification for northern Alaska coals...... 122 8 Relative compositions of coal maceral groups and theliptinite macerals................................ 123 Introduction Thisreport is a summary oftheregionalgeology,petroleum geology,andenvironmentalcharacteristicsoftheNortonBasin PlanningArea. To some extent,theinterpretationshereinare based on previous detailed studies by the Minerals Management Service (MMS) of two deepstratigraphictest wells, theNortonBasin COST No. 1 and No. 2 wells(Turnerandothers, 1983a,b). However, since the release of these reports, a great deal of thesedatahavebeen reprocessed and reinterpreted. In addition, new data havebeen collected or become publicallyavailable. In particular,the common-depth-point (CDP) seismic reflection data base has been improvedandexpandedby theinclusion of lines generously released to MMS byWesternGeophysical Company. The NortonBasinPlanningArea(fig. 1) is roughly bounded by theNorton Sound coastline on the east and southeast,the Seward Peninsula on the north, the 63 degree line of north latitude on thesouth, and thedisputed US-USSR 1867 conventionline on the west. The mostprospectivepart of theplanningareaunderlies NortonSound. The volume, quality, and distribution of reservoir rocks, the presence of potential seals, and a diversity of trapping configurationsshould combine to ensure further exploration in the NortonBasin. The timing of sourcerockmaturation in relation to trap development alsoappears favorable for hydrocarbonentrapment. The volume, quality, and distributionofsourcerocksappearto representthe most serious constraints on thepotentialforcommercial hydrocarbon accumulations in the basin. LeaseSale 57, held March 19, 1983, generated $325 million in highbids.Ninety-eightbids were received on 64 tracts; 59 bids wereaccepted, 5 rejected.LeaseSale 100 is scheduledfor March 1986. Six exploratory wells have been drilled in the NortonBasinsince 1984. All of these wells havebeenplugged andabandoned. No commercial hydrocarbon discoveries have been announced. 1 1 GeologicFramework The NortonBasin is locatedoffthecoastofwest-central Alaska,approximatelycoincidentwithNorton Sound (fig.1). It is oneof severalmajor Tertiary basins on theBering Sea continental