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Implementation of Analogs to Assess Undiscovered Petroleum Resources of the Barents Sea Shelf

Klett, Timothy R.1; Pitman, Janet K.1; Gautier, Donald L.2
1 U.S. Geological Survey, Denver, CO.
2 U.S. Geological Survey, Menlo Park, CA.

In 2008, the U.S. Geological Survey (USGS) completed an assessment of potential undiscovered, technically recoverable crude oil, natural gas, and natural gas liquids (collectively referred to as petroleum) resources of the Barents Sea Shelf.

For this assessment, the Barents Sea Shelf was subdivided into seven geologically distinctive assessment units (AUs) based primarily on structural elements—Kolguyev Terrace, South Barents Basin and Ludlov Saddle, North Barents Basin, Novaya Zemlya Basins and Admiralty Arch, Barents Platform North, Barents Platform South, and West Barents Margin.

A global AU database containing geologic and petroleum information on areas in which structural and stratigraphic conditions, as well as petroleum volumes, are better known served as analogs to aid in the estimation of number, sizes, and composition of undiscovered petroleum accumulations in the Barents Sea Shelf. As examples, (1) analogs selected for the Kolguyev Terrace, South Barents Basin and Ludlov Saddle, North Barents Basin AUs include rift/sag basins that have both extensional and compressional structural settings; (2) carbonate shelf margin and reef analogs were selected for the Barents Platform North and Barents Platform South AUs; and (3) analogs characterized by divergent rifted margins with slope, clinoform, and turbidite deposits were selected for the West Barents Margin. Prospect maps and discovery histories of the Barents Sea Shelf AUs were used to calibrate the estimates of the number and sizes of undiscovered accumulations.

A geologic risk of discovering one accumulation of 50 million barrels of oil equivalent or larger within an AU was assigned to those AU’s without discoveries. Specific risk categories included presence of adequate traps and reservoirs, timing of petroleum generation/expulsion with respect to trap formation, and preservation of petroleum accumulations throughout Cenozoic uplift and erosion.

In all but the West Barents Margin AU, major petroleum source rocks are Triassic and Jurassic mudstone and major reservoir rocks include Permian, Triassic, and Jurassic sandstones. In the West Barents Margin AU, major source rocks are Cretaceous marine mudstone and major reservoir rocks include Cretaceous and Paleogene sandstone. Traps for petroleum accumulations in all AUs include folds, faults, and updip stratigraphic pinchouts, as well as other stratigraphic traps.

 

AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009