The Effect of Gravitational Compaction on the Structure of Sedimentary Rocks

Abstract

ABSTRACT Many oil field structures have been attributed either to lateral variation in the compressibility of sedimentary strata or to the settling of sediments over buried hills. So far few or no experimental data have been published as a basis for such theories. In recognition of this need, a study is made of the compressibility of clays and shales, and a table is obtained showing the relation of the porosity of shale to the overburden. The amount of closure due to the settling of mud or shale over a hill 100 feet high is then calculated, and the character of structures produced by vertical compaction is outlined. As a practical application of these quantitative data two areas in Kansas are considered. Finally, the porosity of argillaceous sediments is suggested as an index of pressure metamorphism.