Researchers from the Institute of Applied Ecology of CAS isolated an indigenous strain, Pseudomonas aeruginosa DQ3 from Daqing oil reservoir production water. They found that the strain could anaerobically (non-oxygen needing) produce biosurfactant through bioaugmentation.

This study highlights that “bioaugmenting indigenous biosurfactant producer P. aeruginosa without air injection is promising for in-situ MEOR applications”.

MEOR, the Microbial Enhanced Oil Recovery, refers to a set of integrated technologies involving the use of microbial activities and metabolites to increase crude oil recovery.

Dr. ZHAO Feng, Prof. ZHANG Ying and their colleagues used oxygen-free bioreactor to simulate the oxygen-depleted conditions in oil reservoirs.

During bioaugmentation process, they investigated the changes in bacterial community composition and the production of biosurfactants.

Using high-throughput sequencing technology, the researchers found that Pseudomonas is one of dominant genera in Daqing soil reservoirs.

During the bioaugmentation process, the hazardous bacteria, such as iron bacteria and sulfate-reducing bacteria, they could be controlled at lower quantity level, while the populations (cells/ml) of the beneficial bacteria (hydrocarbon-degrading bacteria and biosurfactant-producing bacteria) could be kept stable or increased.

The bioaugmentation process changes bacterial community, but Pseudomonas is still one of dominant genera.

The bioaugmentation process also efficiently produces biosurfactant, decreases surface tension of culture from 62.9 mN/m to 33.8 mN/m and emulsifies crude oil with EI 24 values up to 58%.

The result of core flooding tests suggests that in-situ production of biosurfactant by strain DQ3 may increase oil recovery efficiency by 5.22%.

The researchers concluded that the bioaugmentation process of P. aeruginosa DQ3 under oxygen-free conditions could not only enhance oil recovery but it could also effectively control hazardous bacteria (e.g., sulfate-reducing bacteria).

The study entitled “Bioaugmentation of oil reservoir indigenous Pseudomonas aeruginosa to enhance oil recovery through in-situ biosurfactant production without air injection” has been published in Bioresource Technology.

The work is financially supported by the National Natural Science Foundation of China and the Program of Daqing Oilfield Company Ltd.