Peculiarities of Hydrocarbon Generation at Great Depths in the Crust

Abstract

This article describes the peculiarities of hydrocarbon generation at great depths in the Earth’s crust. It is shown that all the conditions necessary for generation of oil and gas are kept at great depths in the crust in the zones of high pressures and temperatures. However, generation of hydrocarbons in such settings significantly differs from the processes of oil and gas formation at shallow depths. A complex system of mutual thermobaric factors and distribution of the oil and gas potential at great depths was revealed: the start of generation and the phase distribution of hydrocarbons in the section are largely affected by settling of abnormally high pore pressure, as well as by paleotemperatures that could differ considerably from the present-day ones depending on the age of deposits. It is shown that different thicknesses of catagenetic zones are related to the kinetic rate of oil and gas generation, which depends on the type of kerogen, the gradient of temperature change, pressure, lithology, and hydrogeological conditions of the host rocks, the sedimentation rate, and other factors.