Plant‐Derived Biosurfactant–Saltwater Synergy for EOR in Carbonate Reservoirs

ABSTRACT Sustainable methods for enhanced oil recovery (EOR) are essential to increase hydrocarbon extraction from oil‐wet carbonate reservoirs. This research investigates a biosurfactant derived from Baccharis oxyodonta , an eco‐friendly agent that alters interfacial properties when used with saltwater. FTIR analysis identified saponin‐related functional groups. The critical micelle concentration (CMC) was found to be 5000 ppm through conductivity and surface tension tests. Interfacial tension (IFT) dropped from 38.1 to 12.42 mN/m at the CMC, a 67% reduction. Adding salinity further decreased IFT to 8.15 and 8.93 mN/m at optimal NaCl and CaCl 2 levels, respectively. Wettability changed from strongly oil‐wet (172.5°) to intermediate‐wet (114.78°). These findings highlight the potential of biosurfactant–saltwater systems for sustainable EOR in carbonate reservoirs.