Fully Coupled Thermo-Hydro-Mechanical Modeling by COMSOL Multiphysics, with Applications in Reservoir Geomechanical Characterization

Abstract

In recent years, there has been a fundamental shift in the way researchers were looking at geomechanical and porous media. Because of the complex nature of geomaterials and presence of solid and fluid within a single system it is crucial to consider all the physics involved within the geomaterial system. As part of this research a fully coupled thermo-hydro- mechanical model based on COMSOL's built-in application modes and PDE application mode is developed. The model consists of a three-phase flow model designed as a set of coupled PDE application modes that when coupled with Heat Transfer Module and Structural Module, forms a thermo-hydro-mechanical model. The coupled application modes entail their own relevant boundary conditions depending on the analysis. A Transient elasto-plastic analysis from Structural Module along with necessary formulation is implemented to define the appropriate yield criteria for the shear and tensile failure of the rock. To account for inherent heterogeneity in rock properties, a probabilistic distribution of mechanical and hydraulic properties through external script and interpolation functions available in COMSOL is used. The integrated non-isothermal flow and geomechanical analysis, using the powerful COMSOL multiphysics interface, yields astonishing results indicating the importance of geomechanics in petroleum engineering problems. The results from the analyses demonstrate the impact of geomechanical properties on multiphase flow behavior and vice versa.