NUMERICAL SIMULATION OF MULTIPHASE FLOW IN A POROUS MEDIUM IN THE PRESENCE OF HEAT AND MASS TRANSFER BETWEEN PHASES

Abstract

The work is focused on unstable displacement of a viscous liquid from a porous medium in the presence of chemical interactions between phases. When a viscous liquid is displaced by a less viscous liquid or gas, the Saffman−Taylor instability develops at the displacement front: the less viscous liquid breaks through the layer of the more viscous liquid being displaced, forming "viscous finger" channels in it. With the development of instability, the initially flat interface is perturbed, and the area of contact between the phases increases. This phenomenon must be taken into account when modeling the displacement process with chemical reactions between phases, since the extension of the contact line between the reacting phases leads to an increase in the rate of the chemical reaction. The article provides a mathematical model for describing the process of oil displacement by the thermogas method: when oil is displaced by a mixture of heated water vapor and gas, which enters into an exothermic chemical reaction with oil, resulting in a decrease in oil viscosity and formation CO2, which leads to better displacement. Also, the mathematical model implies the possibility of accounting for subgrid instability by including additional flow terms into the equations. The results of computational experiments based on the described mathematical model are presented.