Dudley H. Cardwell, 1971. "Future Petroleum Potential of West Virginia, Virginia, and Maryland", Future Petroleum Provinces of the United States—Their Geology and Potential, Volumes 1 & 2, Ira H. Cram
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All Paleozoic systems are represented in the contiguous states of West Virginia, Virginia, and Maryland, and constitute a section ranging up to more than 25,000 ft (7,620 m) in thickness. The regional dip on the basement is southeastward, but the numerous folds and faults increase in intensity toward the southeast.
Production is mainly gas, and most is from the Appalachian Plateau province. Trapping is predominantly structural in the east and combined stratigraphic-struc- tural in the west. Reservoirs are usually sandstone, but some production is from chert, limestone-dolomite, and shale.
Pennsylvanian and Upper Mississippian rocks add to the prospects of the deeper objectives. The Greenbrier has limited potential. The prolific "Big Injun" still has good possibilities for increased reserves with the application of new completion techniques. Additional reserves can be expected in the Berea, and there are secondary possibilities in the Weir. The Devonian shale section, very productive in eastern Kentucky, has numerous possibilities in adjacent West Virginia. Extensions of production from the Benson can be expected principally northwest of the present producing area. The Oriskany and associated Huntersville and Helderberg still have good prospects in the eastern part of the area and in east-central West Virginia. Additional discoveries can be expected in the "Newburg"-Williams- port. The Keefer is a secondary target for wells projected to the Tuscarora. The Tuscarora, although generally containing low-Btu gas, is still an exploratory target in many areas. The poorly explored Cambrian- Ordovician, comprising a large volume of sedimentary rock, is believed to have numerous prospects in the area. Although the deep Paleozoic exploration will be costly, a single discovery of economic size in these rocks would be a development of major importance to the industry.
Figures & Tables
The geology of the entire United States, including the continental shelf and slope, was studied by petroleum geologists to determine its petroleum potential. Prospective areas of the 11 regions were assessed qualitatively and, usually, quantitatively.
The prospective basinal area covers approximately 3.2 million sq mi (statute; 8.3 million sq km) and contains approximately 6 million cu mi (25 million cu km) of sedimentary rock above basement or 30,000 ft (9,144 m). Other less prospective areas are, in the aggregate, large.
The prospective area has not been explored adequately. Many high-potential areas are indicated by the geology and extent of exploration, particularly in parts of Alaska, California, Colorado, Louisiana, Mississippi, Montana, New Mexico, North Dakota, Oklahoma, Texas, Utah, and Wyoming, and in parts of the offshore of Alaska, California, Louisiana, and Texas. The prospective Atlantic, Florida, and Alaska continental shelves, and the entire continental slope, barely have been touched by drilling, and other prospective areas and depths on land and the continental shelf remain largely unexplored.
Estimates of potential crude oil reserves of the basinal area only, exclusive of known reserves, range from 227 to 436 billion bbl of original oil in place. The potential probably exceeds the mean of 332 billion bbl. Approximately 32 percent of the oil in place would be recoverable at known rates of recovery. Ultimately, the rate of recovery may reach 60 percent.
Estimates of potential natural gas reserves exclusive of known reserves range from 595 to 1,227 trillion cu ft of recoverable natural gas. The gas potential also probably exceeds the mean of 911 trillion cu ft.
The ultimate petroleum potential of the United States, including known reserves, may exceed 432 billion bbl of crude oil, 1,543 trillion cu ft of natural gas, and 49 billion bbl of natural gas liquids.
Finding and developing the large petroleum potential will require a great amount of drilling because a significant percentage of the visualized undiscovered crude oil and natural gas is in stratigraphic traps, combination stratigraphic and structural traps, reefs, and complex structural situations. Estimates of future domestic demand call for accelerated exploration. To the extent that policies of industry and government militate against accelerated exploration, particularly drilling, a high percentage of the petroleum resources of the United States will not be reduced to possession.