A New Coupled Approach to Simulating Fault Reactivation During CO₂ Sequestration

Carbon Capture and Storage (CCS) is considered an important means to reducing CO₂ emissions. One of the key technical risks associated with large scale CCS implementation is the potentially induced fault reactivation. To assess this risk, a coupled numerical approach was established by integrating three different software packages over four steps. Firstly, a field-scale structural geological modelling was conducted using the JewelSuite based on available geological, geophysical, and logging data. Secondly, dynamic CO₂ injection was simulated using the reservoir simulator IMEX to predict reservoir pressure build-up. Thirdly, the pressure build-up and the associated reservoir uplift were simulated in the Finite Element software Abaqus. Finally, the Finite Element output database was re-imported into the JewelSuite to delineate the risk areas of fault reactivation. The feasibility of this new approach was tested on a real geological site featuring two faults. The results suggest that, for a given fault setting, the horizontal well placement and bottom hole injection pressure (BHIP) are two critical factors in determining the risk of fault reactivation. To minimise the risk, horizontal wells should not be placed within the intermediate region between faults. Where the borehole placement cannot be optimised, the critical BHIP should be estimated and controlled during operation.