STRATIGRAPHIC AND STRUCTURAL CONTROLS ON GAS PRODUCTION OF THE UPPER DEVONIAN GORDON SANDSTONE LOCATED ALONG THE CATSKILL SHORELINE COMPLEX IN SOUTHERN WEST VIRGINIA

Controls on natural gas production in northern West Virginia from the Gordon Sandstone are well documented, but is poorly understood in southern West Virginia. Correlation of Gordon sediments, via geophysical logs, across the state indicate that the occurrence of Gordon siliciclastic sediments is genetically related. Highly productive Gordon sediments in northern West Virginia were deposited in shallow marine to fluvial environments; moderately productive Gordon sediments in southern West Virginia were deposited as continental shelf sheet sands. The shelf sediments’ geophysical signature can be traced across the state, however varying ratios of sand to silt led to variable Gordon thicknesses across the study area. Geophysical log data are utilized to determine net thickness of the Gordon, individual sand body thicknesses, porosity and permeability. Bulk density and neutron porosity values were used as a proxy for determining porosity per well locale. Permeability was defined per sand body and determined by the input of porosity values into a linear regression model that compared measured porosities against measured permeability values from a previous study conducted by the Department of Energy. Gordon characteristics vary across southern WV: thickness varies ~25ft to 0ft, porosity varies both vertically and laterally within the Gordon interval from ~6% to ~16%, permeability values vary from ~5mD to ~150mD. Porosity and permeability are related to grain size and the degree of sorting of the sediments that comprise the Gordon interval and sub-intervals. The study aims to determine whether the controls on natural gas production are related to the stratigraphy or to structural influence. Mapping the Gordon suggests that the occurrence of natural gas in southern West Virginia is related to the stratigraphy rather that post-depositional deformation.