Geologic CO2 sequestration and permeability uncertainty in a highly heterogeneous reservoir

Abstract To understand the implications of permeability uncertainty in basalt-hosted CCS reservoirs, this study investigates the feasibility of industrial-scale CCS operations within the Columbia River Basalt Group (CRBG). It is generally accepted that plausible constraints on in situ fracture-controlled permeability distributions are unknowable at reservoir scale. In order to quantify the effects of this permeability uncertainty, stochastically generated and spatially correlated permeability distributions are used to create 50 synthetic reservoir domains to simulate constant pressure CO 2 injections. Results from this research illustrate that permeability uncertainty at the reservoir-scale significantly impacts both the accumulation and distribution of CO 2 . After 20 years of injection the total volume of CO 2 injected in each simulation ranges from 2.4 MMT to 40.0 MMT. Interestingly, e-type calculations show that the mean CO 2 saturation over the ensemble of 50 simulations is concentric around the injection well, however, ensemble variance shows an ellipse of uncertainty that trends parallel to the long axis of CRBG permeability correlation (N40°E). These results indicate that a priori knowledge of permeability correlation structure is an important operational parameter for the design of monitoring, measuring, and verification strategies in highly heterogeneous CCS reservoirs.