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The AAPG/Datapages Combined Publications Database

AAPG Special Volumes


Pub. Id: A031 (1985)

First Page: 379

Last Page: 402

Book Title: SG 20: Alaska North Slope Oil-Rock Correlation Study: Analysis of North Slope Crude

Article/Chapter: North Slope Alaska Oil-Rock Correlation Study: SOURCE ROCK EVALUATION INCLUDING ISOTOPES AND BIOMARKERS

Subject Group: Geochemistry, Generation, Migration

Spec. Pub. Type: Studies in Geology

Pub. Year: 1985

Author(s): W. B. Hughes, A. G. Holba, D. E. Miiller


The major objective of the U.S. Geological Survey-sponsored cooperative North Slope Alaska oil-rock correlation study was to establish, using a diversity of geochemical techniques, which formation(s) served as source(s) of the crude oils from the North Slope of Alaska. A second objective was to allow intercomparison and calibration of geochemical technologies among the university, petroleum industry, government, and private geochemical laboratories participating in the study.

Two major groups of oils were identified. Group I includes oils from the Umiat and Simpson areas. These oils are generally low in sulfur, nitrogen, and asphaltenes, have medium gravities, have nickel/vanadium ratios >= and pristane/phytane ratios >1.5, and are high in diasteranes. Group II includes oils from the Barrow, Fish Creek, and Prudhoe Bay areas. These oils are generally high in sulfur, nitrogen, and asphaltenes, have low gravities, have nickel/vanadium ratios <1 and pristane/phytane ratios <1.5, and are moderate in diasteranes.

Both groups of oils are of mixed but predominantly marine source input and are quite mature thermally. The triterpane patterns of the Group I oils contain certain C30 pentacyclics, are low in tricyclics, and have hopane > norhopane. The Group II oils are devoid of the C30 pentacyclics found in Group I oils, high in tricyclics, and have norhopane >= hopane.

The Kingak Shale appears to be the principal source of the Group I oils. However, the Group I, Seabee No. 1 condensate is believed to originate in the Torok Formation. The Group II oils have their principal source in the Shublik Formation but have to varying degrees the Kingak as a co-source. The Barrow pebble shale sandstone oil has major Kingak input; the Barrow Sag River Sandstone, Fish Creek, and Prudhoe Bay oils have minor Kingak input. The Dalton area oil produced from the Lisburne Group, included in Group II because of its overall similarity to these oils, is believed to be indigeneous to the Lisburne.

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