During thermal impact with water or overheated steam on formation, kerogen thermal conversion can be initiated in the rock containing solid organic matter. At the first stage of this transformation liquids and gases, formed during the conversion, occupy the former kerogen volume. Subsequently water substitutes hydrocarbons in the pore volume. So the sophisticated process of rock pore space transformation occurs with changing porosity and permeability and it essentially depends on heating rate and exposure periods. Porosity and permeability are some of the most crucial and sensitive parameters of rock in numerical modelling of thermal enhanced oil recovery (EOR) methods. Experimental studies were conducted first on crushed and then on cylindrical Bazhenov formation core samples to obtain porosity and permeability changes at different exposure periods. The influence of heating rates and sizes of rock chips on the amount of hydrocarbons produced in the tests was evaluated. Time dependencies of porosity and permeability of Bazhenov formation cores were obtained from the tests conducted at 350 °С and 25 MPa. The experiments show that application of hydrothermal treatment method allows to improve filtration properties of Bazhenov formation cores. The results are to be applied to the numerical model of reservoir development with thermal EOR. It was determined that the results of the experiments conducted on cylindrical core samples significantly differ from the observed effects among crushed cores, both in terms of changes in porosity and permeability characteristics and the amount of the recovered synthetic hydrocarbons.
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