--> Abstract: Future Exploration Plays In The Western Colville Basin And National Petroleum Reserve, Alaska (Npra), by C. G. (Gil) Mull, R. R. Reifenstuhl, E. E. Harris, and R. A. Kirkham; #90928 (1999).

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MULL, C. G. (GIL)1, R. R. REIFENSTUHL1, E. E. HARRIS1, R. A. KIRKHAM1, and T. E. MOORE2
1Alaska Division of Geological and Geophysical Surveys, Fairbanks, AK
2U.S. Geological Survey, Menlo Park, CA

Abstract: Future Exploration Plays in the Western Colville Basin and National Petroleum Reserve, Alaska (NPRA)

Recent discovery of the giant Alpine oil field in Upper Jurassic sandstones of the northern Arctic Slope has focused exploration attention on the National Petroleum Reserve, Alaska (NPRA). Extension of exploration trends west along the Barrow Arch from the Prudhoe Bay-Kuparuk area into northeastern NPRA will likely concentrate initially on Neocomian sandstones both above and below the Lower Cretaceous (Hauterivian) unconformity (LCU) and on Jurassic sandstones. Additional plays may develop in deltaic facies of the Nanushuk Group (Albian-Cenomanian) and prodeltaic Torok Formation (Albian).

Recent field studies in the foothills of the western Brooks Range have revealed rich oil-prone source rocks in the pebble shale unit (Hauterivian), which appears to overlie a well developed LCU and organic-rich beds in the Kingak Shale (Jurassic-Valanginian) and Shublik Formation (Upper Triassic). The clay-rich facies are similar to those adjacent to the Barrow Arch of the northern Arctic Slope, and contrast sharply with the distal siliceous facies expected in this southwestern part of the Colville Basin. The presence of the LCU interval and rich source rocks suggests that Neocomian to Jurassic exploration plays associated with the Barrow Arch may be present in western NPRA and adjacent areas, including the eastern Chukchi Sea. Elsewhere in the foothills belt of the western Brooks Range, mapping and facies studies indicate penecontemporaneous deformation that locally affects deposition of deltaic rocks of the Albian Nanushuk Group. The possibility of rapid facies changes, pinchouts, and onlap of marine to nonmarine sands onto structural highs in the subsurface suggests potential for previously unrecognized exploration plays in the Nanushuk and Torok of southern NPRA.

AAPG Search and Discovery Article #90928©1999 AAPG Annual Convention, San Antonio, Texas