Petroleum evaluation of Ordovician black shale source rocks in northern Appalachian basin
A preliminary appraisal of the Ordovician black shale source beds in the northern part of the Appalachian basin shows that the sequence is composed of the Upper Ordovician Utica Shale and its correlatives. The shales range in thickness from less than 200 ft in the west to more than 600 ft in the east along the Allegheny Front. Structure contours indicate that the shales plunge from 2,000 ft below sea level in central Ohio and to about 12,000 ft below sea level in central and northeastern Pennsylvania. Geochemical analyses of 175 samples indicate that the sequence has an average total organic carbon content (TOC) of 1.34%. Conodont alteration indices (CAI) and production indices indicate that the stages of maturation range from diagenetic in the less deeply buried western part of the basin, which probably produced mostly oil, to catagenetic in the more deeply buried eastern part of the basin, which probably produced mostly gas. Potential for continued hydrocarbon generation is poor in the east and fair to moderate in the western part of the basin. If the authors assume that these rocks have produced hydrocarbons, the hydrocarbons have since migrated. Using an average TOC of 1%, an organic carbon to hydrocarbon conversion factor of 10%, and a volume of rock within the oil and gas generation range as defined by CAI values of 1.5-4, the Ordovician shale could have generated 165 billion bbl of oil or equivalent. If only 1% of the 165 billion bbl was trapped after migration, then 1.65 billion bbl of oil or equivalent would be available for discovery.
- Research Organization:
- Geological Survey, Reston, VA (USA)
- OSTI ID:
- 5877897
- Report Number(s):
- CONF-8809345-
- Journal Information:
- AAPG Bull.; (United States), Vol. 72:8; Conference: AAPG Eastern section meeting, Charleston, WV, USA, 13-15 Sep 1988
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
APPALACHIAN BASIN
PETROLEUM DEPOSITS
SOURCE ROCKS
BLACK SHALES
GEOCHEMISTRY
GEOLOGIC TRAPS
MATURATION
ORDOVICIAN PERIOD
SEDIMENTARY BASINS
BITUMINOUS MATERIALS
CARBONACEOUS MATERIALS
CHATTANOOGA FORMATION
CHEMISTRY
ENERGY SOURCES
FOSSIL FUELS
FUELS
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC FORMATIONS
GEOLOGIC STRUCTURES
MATERIALS
MINERAL RESOURCES
OIL SHALES
PALEOZOIC ERA
RESOURCES
020200* - Petroleum- Reserves
Geology
& Exploration