Abstract: The amount of hydrocarbons expelled from argillaceous sediments (or kerogen) under elevated temperatures and pressures is estimated through the experiment which simulated the conditions of geopressure, geotemperature, the contact of source bed and reservoir, and the anaerobic environment. It provides a basis for the appraisal of oil/gas resources. In addition, according to the result of the simulation, the mechanism of primary migration is discussed.