3-D Leakage and Seismic Hazard Assessment for a Potential CO2 Storage Site in the Southern San Joaquin Basin, CA

Abstract We investigate the hazards of leakage and induced seismicity for a potential CO2 storage site in the southern San Joaquin Basin, CA. Total injection is scheduled for 12.3 MtCO2 with variable rates over 18 years followed by 100 years of monitoring. We extend our prior analysis from 2-D to 3-D to account for variations in rock properties and the state of stress with depth. The CO2 saturation and pressure fields are simulated in a 3-D reservoir model that is optimized to minimize the pressure change on faults and the overall size of the CO2 saturation plume. We estimate CO2 and brine leakage rates along faults and existing wells that intersect the storage formation using the NRAP OPEN-IAM tool. We construct a vertical stress profile for site from pilot well data and estimate the probability of fault slip using the Fault Slip Potential tool. Faults and existing wells that penetrate the storage reservoir allow for brine and CO2 leakage, but leakage rates to USDW are negligible. Faults that are well oriented for slip in the stress field and within the pressure plume of the injector present the greatest hazard of induced seismicity. In the optimal simulation case, the probability of slip on potentially active faults does not increase significantly over the storage period and decreases rapidly to pre-injection values during the monitoring period. This study improves our prior protocol for CO2 storage hazard assessment by considering how 3-D variations in rock properties impact the potential for leakage and slip on faults.