ABSTRACT: Application of Remote Geologic Analysis to Gas Exploration in Devonian Shale

Michael G. Foley, Thomas H. Mroz

Pacific Northwest Laboratory's Remote Geologic Analysis (RGA) system uses a unique, automated pattern-recognition approach to identify potential fracture zones (of any dip from vertical to less than 40°) by coplanar analysis of their geomorphic expression in digital models of topography. For its first oil- and gas-related field trail, the RGA system was applied to the fracture characterization of the Morgantown Energy Technology Center's Study area 1 in the Big Sandy gas field in southwest West Virginia. This site was selected for a blind test of the technology because of the characterization data available from well drilling, gas production, and seismic surveys for evaluating the RGA results. The Morgantown staff used these data and performed a geologic analysis of he region, coincidentally, but separately, from the PNL fracture analysis to ensure that a bias would not be introduced into the interpretations. Structure and isopach maps show significant trends in the faulting and folding of the producing formations that control production volumes, which correlate well with the principal interpreted fracture sets from the RGA results. Three fracture sets for the Big Creek, West Virginia, 1:24,000 quadrangle parallel major geologic structures that are associated with basement faulting (steep dip, northeast trend) and thrust faulting (60° dip, northwest trend). These structures appear, in combination with anticlinal folding. to enhance gas production. To date, only the most prominent fracture planes from the RGA analyses have been correlated with t e large-scale structural features (basement faulting) in the study area. The next step in this field trial will be to determine if lesser planar features from the analyses correlate with the detailed structural geology and regional geomorphology of the rocks exposed at the surface.

AAPG Search and Discovery Article #90998 AAPG Eastern Section Meeting, London, Ontario, Canada, September 10-12, 1990