The great importance of the major or giant oil and gas fields of the United States to the economy and strength of both the petroleum industry and the nation cannot be overemphasized. Such oil fields provided 50.7 percent of the United States production in 1966. It is estimated that they will yield almost 58 percent of the country's ultimate oil production and that they contain approximately 57 percent of the nation's crude reserves.

Accompanying this paper are 26 figures and 2 tables which give pertinent data on the 259 oil and 47 gas giants found in the United States. An important fact shown by these charts and tables is that the rate of discovery of new giant fields is declining steadily in nearly all regions of the country.

Most of the major fields were discovered by deliberate exploration for structural traps. Some structural tests found, usually by accident, other subtle stratigraphic or paleogeomorphic accumulations. Although only few such accumulations have been found--most of them accidentally--the rate of discovery of stratigraphic and paleogeomorphic traps has been relatively persistent through the years. This persistent though "accidental" discovery rate indicates that many more such accumulations must be present throughout the country.

If exploration is to succeed in finding new reserves for even the near future, geologists and management will have to place a greater emphasis on the search for the subtle traps with large accumulations. The requirements to find these large reservoirs are (1) the focusing of exploratory thinking on the geologic conditions under which such traps and accumulations form, and (2) the purposeful and deliberate drilling of more stratigraphic and paleogeomorphic wildcat tests.