A detailed discussion of the geology and hydrocarbon potential of the Atlantic coastal plain, Atlantic offshore, and eastern Gulf of Mexico appears in the two following papers by J. Spivak and O. B. Shelburne (area north of Florida) and E. H. Rainwater (peninsular Florida and eastern Gulf of Mexico). This report is a brief summary of those papers, which cover the area shown in Figure 1.
On the Atlantic coastal plain and adjacent continental shelves in the Atlantic Ocean and eastern Gulf of Mexico, there is no gas production and the limited oil production is confined to a very small area in the southern part of the Florida Peninsula. In Florida, more than 300 exploratory tests have found only four oil fields in the past 26 years: Sunniland (1943); Forty-Mile Bend (1954); Sunoco-Felda (1964); and Lake Trafford (1969). The Forty-Mile Bend field was abondaned in 1956 shortly after its discovery. The Lake Trafford field was discovered in May 1969 and to date contains but one well. Production in all the fields, from a depth of approximately 11,500 ft (3,500 m), is from carbonate rocks in the Sunniland Limestone of Early Cretaceous age. Cumulative oil production in Florida since the first discovery in 1943 through December 31, 1968, amounts to only 15.31 million bbl of 20° gravity oil. Although there is a small amount of closure (less than 50 ft or 15 m) at the Sunniland field, the oil traps in the four Florida fields are more dependent on stratigraphy than structure.
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.