A numerical feasibility study of CO₂ foam for carbon utilization and storage in a depleted, high salinity, carbonate...

Carbon Capture, Utilization, and Storage (CCUS) offers a viable solution to reduce the carbon footprint in the petroleum industry, and foam injection presents a promising method to achieve this while simultaneously increasing oil recovery. In this work, we studied the feasibility of CO₂ foam for co-optimizing enhanced oil recovery and CO₂ storage in a high-salinity carbonate formation. The simulated hydrodynamic model is a depleted formation containing 30% residual oil, with three mechanisms for CO₂ storage: solubility, residual, and mineralization trapping mechanisms. The results showed that after 20 years, oil recovery during foam injection was 2.7 times higher than CO₂ injection, and the CO₂ stored during foam flooding was 38% higher than CO₂ injection. Notably, foam injection also increased CO₂ storage capacity by 2.6 times, indicating the potential to store around 2 gigatons of CO₂ in the simulated model. This was attributed to the ability of foam to significantly reduce gas mobility and thus form isolated bubbles through its Jamin effect. Residual trapping was the dominant trapping mechanism, contributing to over 70% of the total CO₂ trapped, attributed to the reduction in the dissolution of CO₂ in brine due to the high salinity of the aqueous medium. CO₂ mineralization was also studied, showing the least trapping efficiency and the dissolution trend of all the carbonate minerals. This study illustrates a novel CO₂ utilization and storage technique in which CO₂ is concurrently sequestered while enhancing oil recovery in a depleted oil reservoir by injecting CO₂ as foam. The relevance of this study lies in its potential to provide a dual benefit of reducing greenhouse gas emissions and boosting oil production, offering a sustainable approach for the petroleum industry.