Fully Coupled Thermal-Hydraulic-Mechanical Reservoir Simulation with Non-Isothermal Multiphase Compositional Modeling

Abstract

Abstract We present the development and application of a multi-physical simulator for evaluating the combined thermal-hydraulic-mechanical behaviors of petroleum reservoirs. The simulator combines non-isothermal multiphase compositional modeling with coupled geomechanical simulation module. The simulator consists of two major modules, namely, the fluid and heat flow module and the geomechanical module. An isenthalpic flash calculation approach is implemented in the fluid and heat flow module. In the flash calculation module, a nested approach is adopted, in which PT flash calculations are conducted in the inner loop and temperature is updated in the outer loop. The iteration is continued until both the fugacity and energy stopping criteria are satisfied. An improved version of the Beltrami-Michell equation, called extended Beltrami-Michell equation, has been derived and implemented in the geomechanical simulation module to simulate heterogeneous and plastic behavior of formation rocks. The three normal stress components inside the stress tensor are solved simultaneously with the pressure and enthalpy in the fluid/heat module, ensuring the mass/energy conservation. The newly-derived extension of the Beltrami-Michell equation is capable of handling materials with changing mechanical properties. This way, the simulator is able to capture the phase change as well as the poro-mechanical effects on rock deformation induced by fluid injection/extraction. The multi-physics simulator is built on an object-oriented parallel simulation framework, with a speedup factor up to hundreds.