Thermo-hydro-mechanical model of rock behavior during the steam assisted gravity drainage process

Abstract

Steam assisted gravity drainage is an effective method of crude oil recovery. Injection of the hot steam into the reservoir leads to the substantial decrease of the oil viscosity and, therefore, increase its mobility. Effective application of this technique requires the development of a coupled mathematical model taking into account complex interaction between mechanical, thermal and hydrodynamic processes and allowing to assess the profitability of oil production in regions with complex geological and physical conditions. In this work, the coupled thermo-hydro-mechanical model of porous media is proposed. According to the model, the porous media is considered as a multiphase system including four components: hot steam, water, oil and solid skeleton. It is assumed that pores are completely filled with the two immiscible fluids (water and oil). The change in the oil viscosity is the result of the change in the temperature only. Volume changes of the solid skeleton are caused by the thermal expansion and change in the pore pressure. In turn, the volume changes lead to the alteration of the permeability and fluid velocity. The proposed model was applied to the simulation of the steam assisted gravity drainage process in the oil sand. The obtained results allowed us to analyze the influence of technological parameters (temperature of the injected steam, pressure of the injected steam) on the stress- strain state of the reservoir and the oil production rate.