Geological CO2 storage: Incorporation of pore-pressure/stress coupling and thermal effects to determine maximum sustainable pressure limit

Abstract

Abstract Ensuring geomechanical integrity is a critical factor in the successful operation of geological CO 2 storage. Injecting pressurized cold CO 2 into a reservoir will trigger two geomechanically coupled phenomena, hydro- and thermomechanical coupling, which should be taken into account when determining the maximum sustainable pressure limit. In this regard, we briefly introduce poroelastic and thermally induced stresses as cold fluid is injected into a geologic formation. We then propose new equations that incorporate pore-pressure/stress coupling and thermal stress effects to calculate for various stress regimes—including normal-, reverse-, and strike-slip faulting—the maximum pressure limit before reactivation of preexisting fractures. The suggested equations are tested for a case study in the literature in which the maximum pressure limit was estimated based on complex numerical simulations. Lastly, sensitivity analysis based on these suggested equations sheds light on how sensitive the maximum pressure limit is to several input parameters, including saturated rock density, Biot's coefficient, Poisson's ratio, initial total horizontal-to- vertical stress ratio, temperature drop, and Young's modulus.