Richard W. Volk, 1971. "Petroleum Potential of Eastern Colorado, Western Nebraska, Southeastern Wyoming, and Northeastern New Mexico", Future Petroleum Provinces of the United States—Their Geology and Potential, Volumes 1 & 2, Ira H. Cram
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The southeastern most district in the northern Rocky Mountains includes 85,000 sq mi (220,000 sq km) in eastern Colorado, western Nebraska, southeastern Wyoming, and northeastern New Mexico. The dominant structure is the Denver basin, but the Las Animas arch is an important factor in local accumulations and, with the Raton basin, merits careful study for future potential. Pre-Mississippian systems offer little promise of future discoveries because source beds are lacking, and the Triassic-Jurassic section also is unfavorable. Mississippian, Permian, Pennsylvanian, and Cretaceous reservoirs offer the best possibilities, in that respective order of increasing importance. Subsurface information is scant in most of the district for the pre-Cretaceous rock section, and comparatively little of the area has been explored for stratigraphic traps. The original reserve of 2.2 billion bbl of oil in place conceivably may be doubled, but an addition of only 410 million bbl is rated as "probable." Future gas reserves may be 980 billion cu ft ("probable" and "possible") and, speculatively, even greater.
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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.