Dynamic Assessment of Basin-scale Pressure Dissipation and Impact on Storage Capacity Using Accelerated Methodology

Abstract

Storage capacity of closed or semi-closed aquifer systems is constrained by build-up of overpressure. Estimation of pressure- constrained storage capacity of a basin-scale resource should be obtained by dynamic simulation of multi-site CO2 injection. The limitation on pressure can occur near the injection where overpressure is greatest, or further away where the basin is shallower. Pressure build-up and dissipation can be impacted by heterogeneity and far-field boundary conditions, which may involve significant uncertainty. The impact of uncertainty in heterogeneity on pressure-constrained capacity is not very well understood due to the computational burden of basin-scale simulations. In this study, we quantify the uncertainty of storage capacity due multi- site injection within a large-scale heterogeneous aquifer system using ensemble-based methods. The approach is accelerated by employing simplified vertical equilibrium methods for the forward model. We find that uncertainty in large-scale heterogeneity results in a wide distribution of estimated capacity, however the estimated mean is less sensitive to variation of the geostatistical model. The effect of average permeability and change in boundary conditions has a greater impact on the estimated mean than variation in the underlying geostatistical model. This implies that for large-scale systems, heterogeneity is important to take into account, but precision in the geostatistical model is less important than other basin-scale quantities.