Enhanced oil recovery techniques are usually controlled by the cost associated with them as the fluctuation in the oil price, over the last years, is now commercially accepted. Microbial Enhanced Oil Recovery (MEOR) is one of the technologies that can potentially be implemented with an exceptionally low operating cost. Apart from economical interests of MEOR, microbial bio-products are found to be more environmentally friendly. Besides, some of the bio-products are more chemically stable in reservoir conditions of high temperature and salinity.

In this study, biosurfactants produced by Bacillus licheniformis species isolated from oil contaminated soils from different parts of the Sultanate of Oman were investigated. Eight different production media using different sugars as carbon source such as: glucose, sucrose and cane molasses were tested on three of the potential strains to select the best medium that maximized the production of biosurfactants which was supported by the interfacial tension (IFT) reduction. All isolates were tested on their potential media to screen for the best biosurfactant producer among the available strains. It was found that the strain W19 gave the maximum IFT reduction (from 46.6 to 3.28 mN/m) in 16 hours of incubation when grown in medium 7.

Further studies on W19 were done to test the interaction of biosurfactant produced by this strain with porous media in core flooding experiments as a tertiary recovery stage. The results showed high potential of using this bacterium during ex situ MEOR applications where 10% of residual oil was recovered after injecting the biosurfactant solution. Further recovery was observed after concentrating the same biosurfactant solution where additional 13% of residual oil was recovered.

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