A Hydromechanic-Electrokinetic Model for CO2Sequestration in Geological Formations

Abstract

In this contribution, a finite element model for simulating coupled hydromechanic and electrokinetic flow in a multiphase domain is outlined. The model describes CO2 flow in a deformed, unsaturated geological formation and its associated streaming potential flow. The governing field equations are derived based on the averaging theory and solved numerically based a mixed discretization scheme. The standard Galerkin finite element method is utilized to discretize the deformation and the diffusive dominant field equations, and the extended finite element method, together with the level-set method, is utilized to discretize the advective dominant field equations. The level-set method is employed to trace the CO2 plume front, and the extended finite element method is employed to model the high gradient in the saturation field front. The mixed discretization scheme leads to a highly convergent system, giving a stable and effectively mesh-independent model. The capability of the model is evaluated by verification and numerical examples. The numerical analysis shows that the streaming potential peak moves with the saturation front, and hence, measuring the streaming potential can be utilized for monitoring CO2 flow remotely.