The Petroleum System--From Source to Trap

MAGOON, LESLIE B., U.S. Geological Survey, Menlo Park, CA, and WALLACE G. DOW, DGSI, Houston, TX

Sedimentary basins, petroleum systems, exploration plays, and drillable prospects may be viewed as separate levels of petroleum investigations, all of which are needed to better understand the genesis and habitat of hydrocarbons. Each level emphasizes particular exploration aspects, for example, (1) sedimentary basin--stratigraphic sequence and structural style; (2) petroleum system--genetic relationship between a source rock and an accumulation; (3) exploration play--geologic similarities of a series of traps; and (4) drillable prospect--individual trap. Except for the "petroleum system," these terms are widely utilized by petroleum geologists.

A petroleum system encompasses a hydrocarbon source rock and all generated oil and gas accumulations and includes all the elements that are essential for an oil and gas deposit to exist: source rock, overburden, reservoir, seal, and trap. All these elements must be in place temporally and spatially such that the processes required to form a petroleum deposit can occur. The processes include the generation, migration, and accumulation of hydrocarbons. The system has a stratigraphic limit, geographic extent, duration time, and preservation time. The procedure to identify, name, and classify a petroleum system is discussed. Its name combines the names of the source rock and the reservoir rock and also expresses a level of certainty--known, hypothetical, and speculative. As examples, the etroleum systems in the Cook Inlet area are discussed.

AAPG Search and Discovery Article #91004 © 1991 AAPG Annual Convention Dallas, Texas, April 7-10, 1991 (2009)