--> Abstract: Targeting Coalbed Methane Exploration Fairways In The Colville Basin, North Slope, Alaska, by R. Tyler, A. R. Scott, and J. G. Clough; #90928 (1999).

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TYLER, ROGER1, ANDREW R. SCOTT1, and JAMES G. CLOUGH2
1Bureau of Economic Geology, The University of Texas at Austin
2Division of Geological and Geophysical Surveys, Department of Natural Resources, State of Alaska

Abstract: Targeting Coalbed Methane Exploration Fairways in the Colville Basin, North Slope, Alaska

Through targeting an exploration fairway in the Colville Basin, along the North Slope, the coalbed methane (CBM) potential may be realized for some rural villages. Areas with potential for CBM resource development will require dynamic ground-water flow and the migration of thermogenic gases through coals of high rank and high gas content toward no-flow boundaries and the conventional and hydrodynamic trapping of migrated and solution gases along those barriers. In the western Colville Basin, an exploration fairway between the villages of Wainwright and Atqasuk and an area 30 mi south of these villages are defined as such areas of conventional trapping, and the traps are postulated to be both structural and stratigraphic. Stratigraphic traps are related to updip pinch-out of the coal beds behind the progradational shoreline sequences of the Cretaceous Nanushuk Group. Structural traps consist of fault-cored anticlines related to the Brooks Range and Barrow Arch orogenesis. Moreover, the updip migration of thermogenic gases within the coal beds and the trapping of the migrated gases beneath impermeable permafrost layers should also be considered a targeted source of gas in combination with exploring for CBM resources. Coal ranks are favorable for resource development with ranks approaching the high-volatile A bituminous, at depths of less than 6,000 ft. Evidence of some saline water beneath the permafrost, however, suggests that meteoric recharge from the Brooks Range may be restricted. Therefore, gases should be predominantly thermogenic and migrated thermogenic gases. With formation testing exceeding 1 MMcf/d between 0 and 3,000 ft, an advanced CBM reservoir characterization and drilling program is recommended for the defined exploration fairway.

AAPG Search and Discovery Article #90928©1999 AAPG Annual Convention, San Antonio, Texas