Geomechanical Modeling and Minimum Fracture Pressure Prediction of CO2 Storage Reservoir Caprock in the Lloydminster Area

Abstract

Abstract Acknowledging the critical imperative to reduce CO2 emissions globally, there is a heightened drive towards adopting the preferred CCUS technology to achieve sustainable greenhouse gas reduction. CCUS requires a reliable caprock integrity to prevent CO2 migration and ensure the success of the injection program. Nevertheless, the impact of mineralogical alterations on caprock integrity continues to elude comprehensive understanding through research. This study investigates the evolution of caprock integrity resulting from long-term CO2 storage-induced mineralogical changes. A 2D Voronoi model is developed to predict the minimum fracture pressure of sideritic shale caprocks with varying mineral compositions in the Waseca heavy oil formation, Canada. The numerical simulations are validated against geomechanical test results, showing good agreement. Sensitivity analysis reveals visible variations in the plastic deformation process due to CO2-water-rock reactions and mineral transformations. Results indicate that caprocks with higher hard minerals, such as quartz, exhibit higher minimum fracture pressures. Additionally, positive interactions between siderite and feldspar intensify cementation within the pore structure. This study provides valuable insights into the mineralogical change effects on caprock integrity and offers a reliable framework for assessing caprock integrity during long-term CO2 storage.