Molecular scale understanding on the oil-water-calcite wettability: role of acid component and effect of CO<sub>2</sub>.

This study employs molecular dynamics simulations to investigate the interplay between CO2, adsorbed organic acids, and the calcite surface, which significantly impacts carbon capture, utilization, and storage (CCUS) processes. The results demonstrate that CO2 can displace adsorbed butyric acid from the calcite surface, reducing the water contact angle and restoring hydrophilicity. This wettability shift is attributed to the formation of hydrogen bonds between CO2 and the carboxyl groups of the acid, disrupting its interaction with the calcite. These molecular-scale insights provide a fundamental understanding of the interfacial phenomena involved in CCUS and enhanced oil recovery operations.