Coupled Thermo-Hydro-Mechanical-Chemical Modeling of Water Injection in Chalk Reservoirs

Abstract

Reliable prediction of the rate- and fluid-dependent evolution of elasto-plastic strain in chalk is essential to minimize the risk associated with sea-floor subsidence and subsurface deformation. Experimental observations show that physicochemical interaction between the aqueous solutions and rock surface causes the change of mechanical properties in chalk. Here, we quantify the experimental observations of hydrostatic pore collapse strength and bulk modulus of water-saturated chalk specimens as a function of temperature and sulfate concentration. Further, a wrapper is developed to couple the non-isothermal transport of the multi-phase flow simulator with the geomechanics simulator to consider the impact of the coupled interactions on fluid transport and reservoir deformation. In this study, the interplay between thermo-hydro-mechanical-chemical processes in chalk reservoirs is investigated by means of numerical experiments. Computational results suggest that reservoir pressure depletion, temperature changes, and water weakening play significant roles in controlling the reservoir's deformation and production. Our study also confirms that accounting explicitly for the coupled THMC processes in reservoir simulations of water flooding in chalk is required for reliable prediction of reservoir responses.

Keywords: compaction, subsidence, multiphysics, water weakening, ion adsorption, reactive flow