Comparisons of Upper Devonian and Lower Silurian Tight Formations in Pennsylvania—Geological and Engineering Characteristics
Published:January 01, 1986
Christopher D. Laughrey, John A. Harper, 1986. "Comparisons of Upper Devonian and Lower Silurian Tight Formations in Pennsylvania—Geological and Engineering Characteristics", Geology of Tight Gas Reservoirs, Charles W. Spencer, Richard E. Mast
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Most Upper Devonian and Lower Silurian reservoirs in Pennsylvania have stratigraphic traps (pinch-outs, porosityture trends throughout western Pennsylvania probably influenced the migration of fluids and the diagenesis of sediments. Reservoirs comprise a variety of quartzose, lithic, and feld- spathic sandstones whose diagenetic histories included formation of authigenic clays, cementation, dolomitization, solution of cements and grains (resulting in secondary porosity development), and recementation. Permeabilities and porosities (most of which are secondary) tend to be low.
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Geology of Tight Gas Reservoirs
Tight gas reservoirs occur in low-permeability, gas-bearing formations that are present to some extent in all gas-producing basins worldwide. This is the first volume to bring together data on tight reservoirs for a variety of basins and different geologic settings. The papers in this volume discuss characteristics of some of the most significant tight gas areas in the United States; however, these data are equally applicable to many other recognized and unrecognized tight gas provinces in other nations. In general, tight reservoirs in the United States are grouped into tight gas sandstones and eastern Devonian shales. The Devonian shale sequences are dominantly marine shale but include some siltstone and sandstone. Tight gas sandstone formations of other than Devonian age are present throughout the United States and consist primarily of fluvial and marine sandstones and siltstones. In addition, gas also occurs in low-permeability marine carbonate reservoirs. The 14 papers in this volume cover such topics as: coal-bed methane and tight gas sands interrelationships; gas-bearing shales in the Appalachian basin; exploration and development of hydrocarbons from low-permeability chalks; and geologic characterization of low-permeability gas reservoirs.