Experimental Evaluation of Carbonated Water Flooding Using Microfluidics and Coreflooding for Simultaneous EOR and CO ₂ Storage in Sandstone Reservoirs

High Resolution Image Download MS PowerPoint Slide Carbon capture and storage (CCS) in depleted oil and gas reservoirs offers a sustainable pathway to mitigate greenhouse gas emissions through secure, long-term CO 2 sequestration. Understanding CO 2 –brine–oil interactions at the pore and core scales is critical for predicting the fate of injected CO 2 and optimizing storage efficiency. This study presents integrated microfluidic and coreflooding experiments to evaluate carbonated water/brine flooding (CWF) in both model and crude oil systems under varying pressure and salinity conditions. At low pressure (150 psig), CWF showed negligible change in residual oil saturation ( S or ) after waterflooding (WF). However, at elevated pressure (700 psig), S or decreased by approximately 12–15%, demonstrating enhanced oil recovery (EOR) potential. CO 2 flooding further reduced residual oil saturation at both low and high pressures. Interfacial tension (IFT) measurements revealed a linear decrease with increasing pressure and a linear increase with salinity for CO 2 -saturated brine–oil systems, whereas produced water–crude oil systems exhibited no significant pressure dependence. Coreflooding experiments confirmed that carbonated water injection enhances oil recovery with increasing pressure, and low-salinity systems outperform high-salinity counterparts. At low pressure (150 psig), increasing salinity reduced the total solubility trapping of CO 2 in both brine and oil. In contrast, at high pressure (700 psig), increasing salinity enhanced total solubility trapping, a trend with significant implications for storage capacity estimates in hydrocarbon-bearing reservoirs. These findings elucidate the interdependence of CO 2 -EOR driven by oil swelling, viscosity reduction, and IFT reduction, and CO 2 storage through solubility trapping, offering practical insights to optimize CCS and carbonated water injection strategies in hydrocarbon-bearing reservoirs.