History of Petroleum Geology and Its Bearing Upon Present and Future Exploration

Abstract

In virtue of the fact that oil and gas are non-replenishable natural resources, the petroleum industry in any region can undergo only a unidirectional evolution. It must have a beginning, a period of ascent, a period of decline, and an end. The petroleum industry in the United States is the most advanced in this respect of any of the major oil-producing regions of the world. According to industry statistics, the United States passed the peak in its rate of oil discovery about 1956, and the peak in its proved reserves at about the end of 1960. During the post-war period from 1945 to 1956, the number of new-field wildcat wells required to make one profitable oil or gas discovery increased from 26 to 52--a 50-per cent reduction in the effectiveness of our exploratory efforts Because well locations are made on the basis of where we think oil (or gas) ought to be, and because our standard procedures are yielding diminishing successes, it behooves us to re-examine the premises on which these procedures are based. This can be done most informatively by reviewing the origin of these ideas. The history of petroleum geology began with formulations of the anticlinal accumulation of oil by three different geologists as early as 1861--within 18 months after the Drake discovery. During the next half century this basic idea underwent many vicissitudes, because oil was found in a great variety of structural positions. The period of 1910-1935, which can be regarded as the Golden Age of petroleum geology, was a period of fundamental and provocative inquiry into basic uestions of origin, migration, and entrapment of oil and gas. Then followed a period of stagnation based on the illusion that the answers to fundamental problems were known. As a consequence, the practice of petroleum geology degenerated into deadening routines of putting rock geometry on maps, and drilling the geometric highs. This state of complacency has been disturbed during recent years as the result of a renewed inquiry originating in industry research laboratories concerning the physics of the rock-water-oil system, and showing that stable accumulations of oil and gas are possible in plunging noses and structural terraces, homoclinal dips, and even in the deep, structurally negative parts of geosynclinal basins. As yet, however, this knowledge does not appear to have exercised much influence on the thinking or practices of rank-and-file petroleum geologists. Because the oil discoveries resulting from conventional practices, many of which are based on invalid premises of hydrostatics, have passed the point of diminishing returns, and because it is physically possible that large undiscovered accumulations of oil exist which now would be found only by accident, or not at all, perhaps the time has come when petroleum geologists should abandon their preoccupation with over-simple ideas of structural and stratigraphic traps, and return to a recognition that the basic problems of petroleum geology are inseparable from the physical behavior of oil and gas in a combination rock-water environment.