Storage compliance in coupled CO2-EOR and storage

CO2 storage compliance refers to the safe and consistent storage of a captured anthropogenic CO2 slug in an underground geological structure. This paper investigates the storage compliance in coupled CO2 enhanced oil recovery (EOR) and storage projects. Storage compliance requires an oilfield operator to maintain sufficient CO2 injection and storage capacities throughout an industrial-scale CO2 capture and EOR-storage operation. We investigate the uncertainty in two operational parameters that may raise a compliance consideration: annual captured CO2 from the power plant and CO2 injection loss in the oilfield. The objective is to maintain sufficient CO2 injection and storage capacities and maximize the economic benefits from the EOR-storage operation. We formulate and optimize the storage compliance problem using the method of optimization with Monte Carlo simulation. The results show that appropriate adjustment of the water-alternating-gas (WAG) ratio increases both the compliance and the economic benefits. Also, a CO2 storage back-up in a saline aquifer allows the oilfield operator to implement more profitable EOR-storage designs. A risk-seeking operator may practice the saline aquifer back-up option to simultaneously maximize the benefits and mitigate the risk of storage capacity shortage. Finally, EOR-storage operation is less efficient than aquifer storage in terms of storage efficiency, and considerably more profitable in terms of tangible economic benefits.