Charles S. Hill, 1971. "Future Petroleum Resources in Pre-Pennsylvanian Rocks of North, Central, and West Texas and Eastern New Mexico", Future Petroleum Provinces of the United States—Their Geology and Potential, Volumes 1 & 2, Ira H. Cram
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In-place pre-Pennsylvanian petroleum resources now known within the boundaries of the National Petroleum Council's Region 5 (North, Central, and West Texas and eastern New Mexico) total 15 billion bbl of crude oil. Projections suggest that 4.9 billion bbl remains to be found. This estimate indicates that for oil this region is about three fourths developed. The bulk of these resources is in two major zones— pre-Simpson and Silurian-Devonian. Total pre-Pennsylvanian rock volume is 68,500 cu mi (285,440 cu km). Average crude oil resources, therefore, are 290,000 bbl per cubic mile.
Known in-place nonassociated gas resources total 23.4 trillion cu ft, and an estimated 51.94 trillion remains to be found. Therefore, gas production is still in the early Stages of development, about one third of the gas resources having been discovered. Discoveries of associated and dissolved gas total 9.57 trillion cu ft, and about 3.22 trillion cu ft remains to be found. This gas is closely associated with oil development and has a similar production history.
Potential calculations of petroleum hydrocarbons disseminated in nonreservoir rocks and of gas dissolved in subsurface waters have been made, although it is realized that they may never rate as reserves.
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.