Outcrops of Turbidite-channel Facies in the Torok Formation: Reservoir Analogs for the Alaska North Slope, USA
David W. Houseknecht, Schenk J. Christopher, 2008. "Outcrops of Turbidite-channel Facies in the Torok Formation: Reservoir Analogs for the Alaska North Slope, USA", Atlas of Deep-Water Outcrops, Tor H. Nilsen, Roger D. Shew, Gary S. Steffens, Joseph R. J. Studlick
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Outcrops of the Lower Cretaceous (Albian) Torok Formation in the Brooks Range foothills of north-central Alaska expose an exhumed, oil-charged stratigraphic trap in a turbidite-channel system (Figure 1). Although scattered along strike for 21 km (13 mi), these outcrops collectively provide a unique and significant analog for an emerging oil play beneath the Alaska North Slope. Recent discoveries 140 to 180 km (90 to 110 mi) north of these outcrops in channelized turbidites of the Torok Formation (Nanuq Field, approximately 40 million barrels of oil recoverable [MMBO]) and Upper Cretaceous Seabee Formation (Tarn Field, approximately 100 MMBO, and Meltwater Field, approximately 50 MMBO) emphasize the magnitude of potential undiscovered resources in this play and suggest the potential for a prospective fairway that extends between the two areas.
The Torok Formation and overlying Nanushuk Formation (Cretaceous, Albian-Cenomanian) comprise sediment derived from the Brooks Range and deposited in a system that prograded eastward and northeastward across the foreland basin (Figure 3). Torok strata include basin-plain and marine-slope facies, whereas Nanushuk strata include marine-shelf, deltaic, and fluvial facies. The study area is located in the foredeep, where Torok submarine-fan and marine-slope facies were deposited basinward of a north-south-oriented shelf margin characterized by significant mass wasting (slumping and sliding of blocks of strata derived from the outer shelf and upper slope) as indicated by seismic data to the north (Houseknecht and Schenk, 2001).
Three generalized architectural elements are defined in the Torok outcrops. C1 is a basal element, comprising poorly sorted,
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Tor H. Nilsen, a red-haired Scandinavian who stood more than six feet tall, died October 9, 2005, at his San Carlos, California, home. This was after a valiant five-year fight with melanoma cancer. He was 63. His ashes were scattered at his family plot in Norway in 2006.
He was born in New York City on November 29, 1941, to Mollie Abrahamson and Nils Marius Nilsen of Mandal, Norway, and was the first of their children to be born in the United States. After graduating from Brooklyn Tech, he earned his B.S. in geology from City College of New York in 1962. While there, his prowess on the basketball court impressed a scout from the New York Knicks, but Tor went on to graduate school and earned his M.S. and Ph.D. degrees in geology from the University of Wisconsin at Madison in 1964 and 1967, respectively. His M.S. thesis was a study of Precambrian metasedimentary deposits in the Lake Superior area, and his Ph.D. thesis was a study of Devonian alluvial-fan deposits of the Old Red Sandstone in western Norway.
Dr. Nilsen’s principal expertise was in depositional systems analysis, stratigraphic analysis, and the relationships among tectonics, eustasy, and sedimentation. He began his industry career in 1967 as a research geologist with the Shell Development Company in Houston, Texas, and Ventura, California, where he worked on the tectonics and sedimentation of Tertiary shelf systems of coastal California. He subsequently spent two years with the U.S. Army Corps of Engineers as the Military