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Gas reserves in the Medina Group of northwestern Pennsylvania were investigated for fracture-porosity and stratigraphic control with remote sensing and geophysical tools. Lineaments were mapped on Landsat MSS band 7 (scale 1:250,000), and RBV (scales 1:125,000 and 1:500,000) images, and low-altitude photographs (scale 1:20,000). Zones of high estimated-net gas reserves were noted along French Creek, between Meadville and Franklin, Pennsylvania. A lineament, which bisects the French Creek lineament and is oriented N55°E, also parallels and overlaps gas-pool trends. The largest gas pool underlies an area devoid of lineaments mapped on Landsat imagery.
The dominant lineament orientations measured from the high- and low-altitude imagery coincide when compiled for the entire study area. This relationship is not evident for individual 7.5^prime quadrangles. Coal cleat orientations, available in the New Lebanon, Sandy Lake, and Kennerdell quadrangles, are not parallel with the dominant lineament orientations. Joint orientations, available in the Meadville quadrangle, coincide with dominant lineament orientations in the area.
The gamma-ray log was used to establish stratigraphic parameters and to approximate lithologies. Sandstones were subdivided into "qualities" representing degrees of shaliness. Other variables derived from this log with respect to the Medina Group include: depth below sea level, formation thickness, net-sandstone thickness, and Cabot Head Shale thickness. The Whirlpool Sandstone Member was not included in this analysis. No statistical correlation was found between the above variables and estimated-net gas reserves. Visual inspection reveals trends common to the isopach maps and estimated-net gas reserves. Thus, stratigraphic control probably is important to hydrocarbon-pool location and geometry, with the proper combination of variables yet to be identified.
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