Geologic CO2 Storage Optimization under Geomechanical Constraints

Summary In this study, an ensemble-based optimization framework has been applied to optimize CO2 injection strategies in a case study representative of storage in depleted gas reservoirs. An optimization problem was formulated for a realistic synthetic case study aimed at investigating the potential value of optimization in the context of CO2 storage. Time-varying yearly CO2 injection rates of multiple injection wells were optimized to maximize the net present value (NPV) of the CO2 storage activities while honoring geomechanical constraints associated with fault stability based on the shear capacity utilization indicator. The results of multiple optimization experiments show that when the constraints are imposed the CO2 injection allocation is more balanced across the injectors and over time. This leads to slightly lower NPV for almost the same amount of CO2 injected in optimized case, but it allows us to identify safe injection strategies that still achieve the storage objectives. These results confirm the potential of numerical optimization as a tool to assist CO2 storage practitioners to design safe injection plans.