Glycolipid Biosurfactants for Enhanced Oil Recovery in High-Wax Crude Oil Reservoirs: A Review

Abstract

High-wax crude oil presents a major challenge to enhanced oil recovery (EOR) because wax precipitation increases oil viscosity and restricts hydrocarbon flow. Although glycolipid biosurfactants have emerged as sustainable alternatives to conventional chemical surfactants, their effectiveness and mechanisms in high-wax crude oil systems remain insufficiently synthesized. This study reviews the application of glycolipid biosurfactants, particularly rhamnolipids and sophorolipids, for EOR in high-wax crude oil reservoirs, emphasizing interfacial tension reduction, wettability alteration, hydrocarbon mobilization, wax degradation, and stability under reservoir conditions. A narrative literature review was conducted using ScienceDirect, PubMed, and SpringerLink, primarily covering publications from 2015 to 2025. Studies were screened for relevance to glycolipid biosurfactants and their reported effects on interfacial tension, critical micelle concentration, emulsification, wettability, viscosity, biodegradation, stability, and oil recovery. Fourteen relevant studies were included and comparatively analyzed using descriptive quantitative comparison and qualitative synthesis. The reviewed studies indicate that glycolipid biosurfactants enhance hydrocarbon mobilization by reducing interfacial tension, shifting wettability toward more water-wet conditions, promoting emulsification, and enabling hydrocarbon degradation or dispersion. Sophorolipids demonstrated strong interfacial activity and stability under elevated temperature and salinity, with reported additional oil recovery of up to 27.27% in sandstone core experiments, while rhamnolipid-based systems achieved a reported 15.4% increase in oil recovery. These findings support glycolipid biosurfactants as promising sustainable EOR agents for high-wax reservoirs, while highlighting the need for pilot-scale validation, long-term stability assessment, adsorption studies, and techno-economic evaluation.