Development of a coupled thermo-hydro-mechanical model in discontinuous media for carbon sequestration

Abstract

Geomechanical alteration of porous media is generally ignored for most shallow subsurface applications, whereas carbon dioxide (CO2) injection, migration, and trapping in deep saline aquifers will be controlled by coupled multifluid flow, energy transfer, and geomechanical processes. The accurate assessment of the risks associated with potential leakage of injected CO2 and the design of effective injection systems require that we represent these coupled processes within numerical simulators. The objectives of this study were to develop a coupled thermo-hydro-mechanical model into a single software and to examine the coupling of thermal, hydrological, and geomechanical processes for simulation of CO2 injection into the subsurface for carbon sequestration. A numerical model was developed to couple nonisothermal multiphase hydrological and geomechanical processes for prediction of multiple interconnected processes for carbon sequestration in deep saline aquifers. The geomechanics model was based on the Rigid Body-Spring Model (RBSM), a discrete method for modeling discontinuous rock systems. Poisson’s effect that was often ignored by RBSM was considered in the model. The simulation of large-scale and long-term coupled processes in carbon capture and storage projects requires large memory and computational performance. The Global Array Toolkit was used to build the model to permit high-performance simulations of coupled processes. The model was used to simulate a case study with several scenarios to demonstrate the impacts of considering coupled processes and Poisson’s effect for the prediction of CO2 sequestration. As a demonstration of the coupled model, a conceptual 3D model was used to explain the double-lobe uplift pattern observed in the Krechba gas field at In Salah (Algeria), a site that demonstrated the success of a CO2 sequestration effort into a deep saline formation.