A fully coupled thermo-hydro-mechanical model for simulating hydro-carbon reservoirs

In an oil reservoirs, the mechanical stresses, the thermal stresses and the fluid pressures can effect on each other and create a completely coupled phenomenon. Reservoir deformations due to thermal and mechanical stresses can cause the changes on effective stress and effect on the rate of production. Similarly, fluid pore pressure and temperature variations can effect on the deformation of reservoirs. Since these phenomena are mutually interacting with each other, considering the effects of temperature, fluid pore pressure and deformation on reservoir production requires the simultaneous simulation of heat, geomechanical and flow equations. In this article, first, the history of thermo-hydro-mechanical modeling is described. Then, the governing equations include three sets of mass equilibrium, momentum equilibrium and energy balance equations are presented for a non-isothermal deformable porous medium that is saturated by three phases of water, oil, and gas. These equations are related to each other and are solved in the form of partial differential equations. Due to being coupled of governing equations and the complexity of their boundary conditions, this equation is usually solved numerically. Different numerical methods have been used for solving which have different positive and negative points. Finally, the numerical solution of coupled thermo-hydro-mechanical equations is described in a finite volume and finite element methods and the examples of porous media simulation are presented. The examples show the ability of the proposed model.