Geological Model Predicting Optimum Sandstone Per Cent for Oil Accumulation

Abstract

ABSTRACT Statistical data on the average thickness of sandstones and the total ultimate recoverable oil for the 7241 reservoir sandstones in the United States suggest that the contact area between the sandstone body and the surrounding shales is the most important factor controlling the oil reserve. This may be understood if the main source of hydrocarbons was in the surrounding shales and they hydrocarbons were squeezed from them by compaction. The fluid-expulsion efficiency would generally increase as the contact area increases. On the basis of the above concept, two different models of sandstone-shale interbeds are considerd in this paper, in order to predict the optimum sandstone per cent for the occurrence of hydrocarbon accumulations. These two models suggest that the optimum sandstone per cent falls between 20 and 60; this is also documented by the statistical data of oil accumulations in different parts of the world.