Poromechanical Simulations and Fault Stability Assessments for CO2 Storage

Geological carbon sequestration is a strategy to decrease the concentration of carbon dioxide in the atmosphere by permanently storing large quantities of CO2 in geological formations. During and post CO2 storage operations, it is crucial to maintain the integrity of the cap rock and prevent fault activation to reduce the risk of CO2 leakage or induced seismicity. To identify and mitigate these risks, a robust numerical simulator is required to simulate the poromechanical deformations of host formations induced by CO2 injections and account for the mechanical influence of faults. The objective of this study is to benchmark GEOS modeling capabilities to model carbon sequestration in faulted reservoirs. GEOS employs a finite volume discretization for the flow equations, coupled with a low-order finite element method for mechanics. Various approaches exist to capture the effects of faults on both flow and mechanics. In this study, faults are explicitly represented by surface elements located at the interface between 3D cells and contact constraints are enforced through the Lagrange multipliers method. We present the verification of the solvers against reference solutions and a numerical investigation evaluating the impact of key parameters, such as fault geometry, permeability, and loading conditions, on the reservoir response and fault stability. The presented results provide valuable insights into fault modeling capabilities in GEOS and its applications for CO2 injection and storage.