microbial enhanced oil recovery using biosurfactant produced by alcaligenes faecalis

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).