A new study led by researchers from the Institute of Applied Ecology, Chinese Academy of Sciences indicates that a bacterial strain isolated from Xinjiang oil reservoir can efficiently produce biosurfactant under anaerobic (oxygen-free) or high pressure conditions and thus is promising for applications in microbial enhanced oil recovery (MEOR).

MEOR refers to a set of integrated technologies involving the use of microbial activities and metabolites to enhance crude oil recovery.

“Stable growth and efficient production of biosurfactant by functional bacteria in oil reservoirs are indispensable for MEOR process”, Dr. ZHAO Feng and Prof. ZHANG Ying, the leading scientists of this study, remark at the beginning of their new paper.

To develop MEOR technology, Dr. ZHAO Feng, Prof. ZHANG Ying and their colleagues isolate two biosurfactant-producing bacterial strains (Bacillus amyloliquefaciens 702 and Pseudomonas aeruginosa 709) from Xinjiang Oilfield, China. They investigate the biosurfactant production by the two strains under aerobic conditions (oxygen-needing), anaerobic conditions and high pressure (10 MPa) conditions. They also compare the oil recovery efficiencies enhanced by the two strains using the core flooding tests.

The researchers find that strains 702 and 709 can aerobically produce 1582.4 mg/l and 8237.5 mg/l of biosurfactant at 39℃. Under anaerobic or high pressure conditions, strain 709 can still efficiently produce biosurfactant, but strain 702 can only produce less than 100 mg/l of biosurfactant. The result of core flooding tests suggests that in-situ production of biosurfactant by strain 709 and 702 may increase oil recovery efficiency by 7.04% and 1.10%, respectively.

The researchers thus conclude that strain P. aeruginosa 709 is “more suitable and advantageous for in-situ MEOR applications.”

The study entitled “Biosurfactant production under diverse conditions by two kinds of biosurfactant-producing bacteria for microbial enhanced oil recovery” has been published in Journal of Petroleum Science and Engineering.

The work is financially supported by the National High Technology Research and Development Program of China (also called 863 Program).