Cyclic CO2-EOR in the Bakken Formation: Variable cycle sizes and coupled reservoir response effects

Furthermore, this study analyzed the combined effect of operational and geological parameters on the three responses of oil recovery, CO2 utilization, and CO2 retention factors. In particular, fracture spacing, fracture half-length, start time of operation, oil gravity, as well as injection pressure were identified as the most influential variables. Interaction effects of the mentioned variables with geological parameters of porosity, pay-zone thickness, and permeability were also studied. The range of operational values which yields the optimum responses for specific geological parameters were identified. The statistical approach also helped provide screening strategies for an optimized operation of a CO2-EOR process in an unconventional reservoir.