Use of a Bio-ASP Solution Composed of an Inorganic Alkali, Surfactin, and Xanthan Gum for Enhanced Oil Recovery

The growing demand for environmentally sustainable enhanced oil recovery technologies has stimulated the development of alternative injection fluids. This study proposes and evaluates a novel biobased alkaline-surfactant-polymer (Bio-ASP) formulation composed of sodium carbonate, the biosurfactant surfactin, and the biopolymer xanthan gum, all derived from renewable resources. A full factorial 2³ experimental design with three central replicates (11 core flooding experiments) was employed to investigate the individual and synergistic effects of these components on sandstone oil reservoirs. The Bio-ASP solutions were characterized in terms of the density, pH, interfacial tension, and viscosity. Results revealed that the surfactin concentration was the main factor in reducing interfacial tension, while xanthan gum primarily controlled viscosity and mobility, both significantly improving the oil recovery factor. The optimized Bio-ASP system achieved up to 63% tertiary oil recovery, outperforming conventional ASP systems reported in the literature. These findings highlight the novelty and technical viability of a fully biobased ASP system, offering a more sustainable and scalable alternative for efficient exploitation of mature or low-productivity reservoirs.