Autogenic gas (self sourced) from shales - an example from the Appalachian Basin

Journal Article · Fri Jan 01 00:00:00 EST 1993 · United States Geological Survey, Professional Paper; (United States)

OSTI ID:7052186

Milici, R C ^[1]

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1. Geological Survey, Denver, CO (United States)

Black gas shales of Devonian and Mississippian age occur over much of the Appalachian basin, extending from eastern Tennessee north- and northeastward into Ohio and New York. In general, these shales were deposited along the distal margin of the Acadian Catskill delta in response to episodes of tectonic subsidence and regional transgression during the Acadian orogeny. A major trend of high organic carbon content in the black shales extends along the western side of the Catskill delta, from southwestern Virginia to the southern shores of Lake Erie. The high content of organic detritus in these Devonian and Mississippian black-shale source beds is probably related to high organic productivity in combination with moderate sedimentation rates along the distal margins of the Catskill delta. In general, organic matter in the black shales is more marine and oil prone on the western side of the basin, away from the major sources of siliciclastic input, than it is to the east. Thermal maturity trends follow depositional strike and isopachs of the Catskill delta and, thus, are related to depth of burial. Fracture porosity within the black shale sequence appears to have been affected mostly by regional decollement within discrete stratigraphic units that were, perhaps, overpressured during deformation. Shale gas is produced from relatively large fields in southwestern Virginia, eastern Kentucky, southwestern West Virginia, and southernmost Ohio. To the north, the strata rich in organic matter are thermally immature, and fields along the southern shores of lake Erie in Ohio and Pennsylvania are only marginally productive. To the east in northwestern West Virginia, the organic content of the shales is diluted by increased amounts of siliciclastics; organic matter is not sufficient to sustain long-term gas production, and shale-gas wells are short lived. 79 refs., 11 figs., 1 tab.

• OSTI ID: 7052186
• Journal Information: United States Geological Survey, Professional Paper; (United States), Vol. 1570
• Country of Publication: United States
• Language: English

Related Subjects

03 NATURAL GAS
APPALACHIAN BASIN
NATURAL GAS FIELDS
NATURAL GAS
PRODUCTION
RESERVES
GEOLOGY
BLACK SHALES
CARBONIFEROUS PERIOD
DEVONIAN PERIOD
ENERGY SOURCES
FLUIDS
FOSSIL FUELS
FUEL GAS
FUELS
GAS FUELS
GASES
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC STRUCTURES
MINERAL RESOURCES
NATURAL GAS DEPOSITS
PALEOZOIC ERA
RESOURCES
ROCKS
SEDIMENTARY BASINS
SEDIMENTARY ROCKS
SHALES
030200* - Natural Gas- Reserves
Geology
& Exploration