Petroleum Potential of Southern Coastal and Mountain Area, California
Cliffton H. Gray, JR., Michael P. Kennedy, Paul K. Morton, 1971. "Petroleum Potential of Southern Coastal and Mountain Area, California", Future Petroleum Provinces of the United States—Their Geology and Potential, Volumes 1 & 2, Ira H. Cram
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The southern coastal and mountain area occupies about 7,000 sq mi (18,130 sq km) in the southwestern corner of California. A narrow coastal strip of sedimentary rocks extends from the Mexican border northward to the vicinity of San Onofre, where it widens and continues north around the northern extremity of the Santa Ana Mountains and southeastward beyond Corona along the Elsinore trough. The rest of the area is a mountainous land underlain mainly by the great mid-Cretaceous batholith of southern California and by older metamorphic rocks. The coastal strip and the Corona vicinity, about 1,000 sq mi (2,590 sq km), are underlain by Late Cretaceous and younger sedimentary rocks, mainly marine. About 175 wildcat wells have been drilled in the area, but evidence of oil and gas is scant. Showings of oil and gas have been reported in a few wells, but petroleum has not been produced. Three possible future petroleum target areas are Corona, the eastern part of the Capistrano basin, and the San Diego coastal strip. The volume of possibly favorable sedimentary rocks has not been quantified, but scattered bits of evidence suggest that favorable Miocene and Pliocene strata, largely in the San Diego area, may aggregate about 50 cu mi (210 cu km).
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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.