The application of basin modeling of oil and gas systems based on the capillary-gravity concept

Abstract

ANNOTATION Oil and gas reservoirs exhibiting low reservoir properties often have significant deviations in structure of hydrocarbon reservoirs they contain, based on anticlinal theory of oil and gas accumulation. First, these deviations are related to sharp fluctuations found in water-oil and water-gas interfaces and failure to subordinate the shape of deposits to structural factor. When dealing with such objects, geologists often have to assign unreasonable structural deflections, various impermeable seals of tectonic or sedimentary origin whose presence is not always confirmed by seismic and drilling data. The reason for such difficulties is that anticlinal theory does not consider capillary forces counteracting hydrocarbon migration to be key to reservoir formation. Any oil and gas reservoir is a multiphase pore system with countless contacts, both between different fluids and in host pore space. As per molecular physics laws, the major role in oil and gas water distribution in such systems is controlled primarily by capillary properties of the environment such as capillary pressure at water-oil interface, interfacial tension magnitude, pore channel radius and wetting behavior of solid phase. Due to capillary forces, sharp fluctuations at water-oil interfaces and significant shifts of oil and gas reservoirs relative to vaults of anticlinal structures are observed