Compatibility assessment of rhamnolipid biosurfactant with reservoir fluids and minerals of sandstone

Abstract

As Indonesia’s mature oil fields decline, biosurfactant-based Enhanced Oil Recovery (EOR) offers a sustainable alternative. This study evaluates the compatibility of rhamnolipid biosurfactant with reservoir fluids and mineralogy of sandstone using Buff Berea Sandstone Sample. Tests were conducted at 0–7.5% rhamnolipid concentrations in brines with salinities of 5000–30,000 ppm NaCl. Rhamnolipid remained stable at high salinities and 60 °C. Mineralogical analysis confirmed quartz dominance (>70%) with reactive silicates influencing biosurfactant retention. IFT decreased significantly with increasing rhamnolipid concentration, most notably between 0% and 1.5%, with greater reduction in light oils. Viscosity increases were prominent in medium oil at medium–high salinity, reaching 18–20 cP, indicating improved mobility control. pH remained stable (5–6), safe for reservoir applications. Contact angle tests showed light oil had higher wettability (15.07°) than medium oil (25.05°), with medium oil offering higher mobilization potential under surfactant-assisted recovery. Results demonstrate rhamnolipid’s strong potential as an efficient, environmentally friendly EOR agent, with chemical and mineralogical compatibility supporting its application in Indonesian oil fields. This integrated evaluation provides insights into biosurfactant behavior in realistic geological conditions.