Oil-Source Rock Correlation Studies, Central Brooks Range Foothills and National Petroleum Reserve, Alaska (NPRA)

By

P.G. Lillis, J.D. King, A. Warden, and M.J. Pribil (U.S. Geological Survey)

As part of an ongoing investigation of petroleum systems within the North Slope of Alaska, new geochemical analyses were conducted on outcrop occurrences of petroleum and potential source rocks from the foothills of the central Brooks Range and southern National Petroleum Reserve (NPRA). Oil seeps, oil-stained rocks, and solid bitumen samples were analyzed for elemental (CHNOS), stable carbon isotope, and biomarker composition and compared with potential source rock extracts from the Carboniferous Lisburne Group, Triassic Shublik Formation, Upper Triassic-Lower Jurassic Otuk Formation, and Cretaceous Torok Formation. Petroleum found in the Cretaceous Nanushuk Group, and the oil seeps found at Umiat and Fish Creek are most likely derived from the Torok Formation. Oil stains and solid bitumen found in the Fortress Mountain Formation and in Torok Formation sandstones are most likely derived from the lower Otuk Formation, which is age-equivalent to the Shublik Formation. Solid bitumen found in the Lisburne and the Otuk appear to be derived from their respective formations. These data combined with previous studies along the Barrow Arch provide a better understanding of the number and extent of petroleum systems of the North Slope.

AAPG Search and Discovery Article #90008©2002 AAPG Pacific Section/SPE Western Region Joint Conference of Geoscientists and Petroleum Engineers, Anchorage, Alaska, May 18–23, 2002.