Comparative numerical study on the co-optimization of CO2 storage and utilization in EOR, EGR, and EWR: Implications for CCUS project development

Carbon capture, utilization, and storage (CCUS) and the geological sequestration of carbon dioxide (CO2) have become effective means of mitigating CO2 emissions and combating global warming. Currently, two main issues influence the implementation and progress of major CCUS technologies (e.g., CO2 geo-storage combined with CO2-enhanced oil recovery (CO2-EOR), CO2-enhanced gas recovery (CO2-EGR), and CO2-enhanced deep saline water/brine recovery (CO2-EWR)): high development costs and negative environmental impacts. Additionally, certain operating and reservoir critical parameters could influence the performance of CCUS technologies, making it difficult to design an optimal development scheme. In this study, a comparative numerical simulation analysis on the co-optimization of CO2 storage and utilization in EOR, EGR, and EWR was performed. A geological model based on the Bakken formation was built, and the influence of critical reservoir parameters (reservoir permeability, porosity, initial reservoir pressure, injection pressure, and production pressure) was observed through sensitivity analysis. The following results were obtained: (1) For CO2-EOR, the CO2 storage capacity increases with operating pressure above the minimum miscibility pressure. (2) Based on the best-case scenario, the CO2 storage capacities of EWR, EOR, and EGR were 189.4 × 106 scf, 252 × 106 scf, and 97 × 106 scf, respectively. (3) According to the best-case analysis, the recovery factor of EWR, EOR, and EGR were 5.2%, 91%, and 12%, respectively. (4) By comparing the best-case storage capacity and recovery factor, the optimal CCUS process was the CO2-EOR technology. The research results will guide future decisions on the development of CCUS projects.