--> An Exploration Strategy Designed to the Requirements for High Gas Rate Open-Hole Cavitation Completions in Coal Reservoirs, by D. Decker, A. Klawitter, and T. Mowers; #90986 (1994).

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Abstract: An Exploration Strategy Designed to the Requirements for High Gas Rate Open-Hole Cavitation Completions in Coal Reservoirs

David Decker, Alan Klawitter, Theodore Mowers

The remarkable success achieved for producing gas from coal seams in the San Juan basin can largely be attributed to utilization of the innovative open-hole cavitation (OHC) technique. Most OHC wells are located within a northwest trending fairway situated in the north central portion of the San Juan basin. Within this fairway, wells completed with the OHC out perform hydraulically fractured wells by a factor of five. Outside the fairway, hydraulically fractured wells typically out perform OHC wells. The production variability is related to regional changes in reservoir conditions as reflected by varying geologic characteristics. The geological parameters leading to successful OHC wells have been inadequately studied for predictability using the OHC technique outside of the existing c vity fairway.

Preliminary production mapping suggests the cavitation fairway is characterized by a northwest-trending fracture zone which has intersected coal reservoirs at full adsorptive capacity. The subsurface fracture system is well expressed at the surface and as such has been comprehensively characterized through interpretation and analysis of Landsat Thematic Mapper, Landsat Multispectral Scanner, and Slide Looking Airborne Radar imagery.

Remote imagery data when coupled with other remote sensing techniques, such as potential field and seismic, established the tectonic and stress models that describe the high permeability fairway. Integration of stratigraphic studies, thermal maturity modeling, water and geochemical isotopic studies confirm the presence of thermogenic gas accumulations in a basin-centered type trap. A multi-disciplinary approach has yielded an understanding to the origin of the San Juan basin cavity fairway and can be used for identifying fairways in other coal bearing basins.

AAPG Search and Discovery Article #90986©1994 AAPG Annual Convention, Denver, Colorado, June 12-15, 1994