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The AAPG/Datapages Combined Publications Database

AAPG Bulletin

Abstract


Volume: 52 (1968)

Issue: 3. (March)

First Page: 562

Last Page: 562

Title: Accumulation of Reservoir Fluids: ABSTRACT

Author(s): William C. Gussow

Article Type: Meeting abstract

Abstract:

The principle of differential entrapment, first published in 1953, is reviewed and updated, and geological evidence for selective trapping of oil and gas is illustrated with many kodachrome slides. This theory explains why many good traps are dry whereas adjacent structures are prolific oil fields. It explains why some traps are gas fields and contain no oil, and why gas is trapped downdip in some areas whereas oil occurs in synclines in other areas. The law of gravity explains the gravity distribution of gas, oil, and water in a reservoir, but differential entrapment explains why some oil reservoirs are stratified.

Oil and gas accumulations are modified under superimposed hydrodynamic conditions in accordance with the hydrodynamic gradient, causing tilted interfaces, spilling, and remigration. When folding and faulting are superimposed on a basin with oil and gas accumulations, the oil and gas usually remigrate into the new structures in accordance with the principle of differential entrapment, and these new accumulations conform to the existing hydrology.

Undersaturated oils, gas-oil ratios, and the origin and significance of saturation pressures are discussed.

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Copyright 1997 American Association of Petroleum Geologists