Synergistic Effects of Binary Surfactant Systems for Enhanced Oil Recovery in Carbonates

Abstract

Abstract This study investigates the use of binary surfactant systems for enhancing oil recovery (EOR) in carbonate formations, which have complex surface charges and harsh conditions (high temperature, high salinity) that limit the effectiveness of single surfactants. Binary surfactants form mixed micelles with lower interfacial tension (IFT) and higher solubilization capacity than single surfactants, thus improving their performance and synergism. We measured the critical micelle concentrations (CMCs) of various binary surfactant ratios and applied Rubingh's Regular Solution Theory (RST) to analyze their behavior and interactions. We found that the binary surfactants had lower CMCs than their individual components, which means less surfactant is needed to achieve optimal surface activity, reducing costs and environmental impact. The nonionic surfactant concentration was a key factor for synergism. We also conducted static adsorption and spontaneous imbibition tests to examine the effects of binary surfactants on oil recovery. We observed that the nonionic surfactant reduced the adsorption of the anionic and cationic surfactants by 53% and 28%, respectively, and increased the recovery factor to nearly 60%. Our results demonstrate the potential of binary surfactant systems for EOR in carbonate formations, as well as for CO2 sequestration and filtration optimization.