Impact of Biosurfactants, Surfactin, and Rhamnolipid Produced from Bacillus subtilis and Pseudomonas aeruginosa, on the Enhanced Recovery of Crude Oil and Its Comparison with Commercial Surfactants

The continuous production of crude oil over the past several years has matured numerous oil reservoirs worldwide. The current study aims to increase the recovery of low-waxy-crude oil using biosurfactants produced by microorganisms. Ex situ biosurfactant-induced microbial-enhanced oil recovery (MEOR) is addressed in this work, and the substantial findings will be useful to predict its performance in reservoirs. Experiments were carried out to investigate the performance of MEOR in porous media using synthetic surfactants and biosurfactants. Mass spectrometry results show that the microorganisms Pseudomonas aeruginosa and Bacillus subtilis produced biosurfactants, such as rhamnolipid and surfactin with molecular weights of 1016 and 355 Da, respectively. The results indicate that higher-oil-recovery efficiency can be achieved using biosurfactants. The concentration of 200 ppm surfactin showed 15.43% of enhancement in oil recovery, whereas 200 ppm rhamnolipid exhibited 15.47% increase in the recovery of oil. However, at the same concentration, cetyltrimethylammonium bromide and sodium dodecyl sulfate enhanced the recovery of crude oil by 7 and 8.82%, respectively. The efficiency of biosurfactants in subsiding the interfacial tension between the crude oil and water system in porous media was observed to be the main cause for improved oil recovery. Enhanced oil recovery even at low concentrations and stability at high salinities, pH values, pressures, and temperatures make surfactin and rhamnolipid excellent candidates as biosurfactants and offer good prospects for their use in MEOR.