Studies of Biosurfactant for Microbial Enhanced Oil Recovery by Using Bacteria Isolated From the Formation Water of a Petroleum Reservoir

Pseudomonas aeruginosa WJ-1, an indigenous rhamnolipid (RL)-producing bacterium, was isolated from petroleum-reservoir brines. The authors studied the effects of carbon and nitrogen sources, and the ratio of carbon to nitrogen (C/N, wt/wt) on RL production. The results demonstrated that waste sunflower oil (at 80 g/L) and NaNO3 was optimum carbon and nitrogen source. The optimized C/N ratio was 8. RL production in 3,000 L intelligent fermenter showed that the maximum yield of RL was 50.2 g/L under optimum conditions. The surface tension of culture decreased from 67.59 to 24.5 mN/m. Physical simulation experiments on microbial enhanced oil recovery showed that the maximum oil recovery of strain WJ-1 and its biosurfactant in sand-packed column was 23.02%.