Microbial Enhanced Oil Recovery Using Biosurfactant Produced by Alcaligenes faecalis

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A bacterial strain (designated as Alcaligenes sp. MS-103) isolated from oil sample of the Aghajari oilfield in the south of Iran, was able to produce an effective extracellular lipopolysaccharide biosurfactant (1.2±0.05 g/l) on molasses as a sole carbon source. The highest surface tension reduction to level 20 mN/m was achieved by biosurfactant produced by cells grown on molasses under optimum conditions. The optimum values of carbon to nitrogen ratio (C/N), salinity, pH and temperature for biosurfactant production were determined as 60:1, 7.5%, 7.0 and 50°C, respectively. Biosurfactant flooding experiments were carried out on both fractured and unfractured carbonate cores. The highest recovery of residual oil among different experiments was about 10.7% in the unfractured cores. Oil displacement indicates that recovery of crude oil can be increased by 9.2% from fractured core with a permeability of 12 mD. The results showed that the biosurfactant produced by Alcaligenes sp. MS-103 has the potential for industrial applications and may be used in microbial enhanced oil recovery (MEOR).