--> Abstract: Brooks Range Foothills Structural Plays – Applicability of Canadian Rockies Foothills Play Types, by Christopher J. Potter and Thomas E. Moore; #90039 (2005)

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Brooks Range Foothills Structural Plays – Applicability of Canadian Rockies Foothills Play Types

Christopher J. Potter1 and Thomas E. Moore2
1 U.S. Geological Survey, Denver, CO
2 U.S. Geological Survey, Menlo Park, CA

Canadian Rockies foothills exploration concepts and production histories provide a valuable template for evaluating the frontier gas and oil potential of the Brooks Range foothills (BRF) in northern Alaska. Comparison of the Canadian foothills (CF) play types (Newson, 2001) with plays developed for USGS assessments of Alaska's North Slope allows a systematic evaluation of the applicability of CF exploration history to the potential for resources beneath the BRF.

Seismic data and outcrop geology show that Newson's first-generation CF plays (single thrust sheet of Mississippian carbonate reservoir in a fault-bend fold) have few parallels in the BRF. Second-generation CF plays (duplex containing Mississippian carbonate reservoir in multiple thrust sheets) have a counterpart in the central BRF, where antiformal stacks of imbricated Mississippian Lisburne Group carbonate rocks occupy a persistent trend that has been tested unsuccessfully for oil in several places. Third-generation CF plays are based on detachment-folded carbonate reservoirs; such structures are also common in the Brooks Range and BRF. The frontal triangle zone play type, important in the CF, is present across much of the BRF, although the clastic reservoir quality in the BRF triangle zone is likely inferior to that in the CF. In the BRF, there are two additional play types that are not prominent in the CF: (1) a frontal detachment fold domain in foreland basin strata to the north of the triangle zone, and (2) basement-involved structures in a forward position beneath the northeastern BRF and adjacent coastal plain.

In the BRF, all of these structural plays are primarily gas plays; the greatest potential for oil is in the northernmost frontal detachment folds. As in the CF, the success of BRF structural plays relies strongly on fracture permeability and possibly on significant fracture porosity.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005