Coupled Analysis of CO 2 Injection Induced Stress Variation in the Caprock

Abstract

Caprock stability is crucial to be assessed in the carbon dioxide underground storage. The CO₂ injection not only generates pressurization but also induces thermal stresses because of the difference in injected CO₂ and in situ temperature. Exhibiting the combination of both effects, the caprock stability needs to be investigated. Numerical simulations are carried out to investigate the effects of thermo-mechanical coupled properties on the caprock stability. The results indicate that for a given geometrical configuration and a given temperature difference between injected CO₂ and reservoir, the deviatoric stress may increase or decrease, depending on the combination of thermal-hydro-mechanical properties: thermal expansion coefficient, stiffness and Poisson’s ratio. Therefore the effects of material properties on the caprock stability should be addressed in a combined way for CO₂ injection problems.