AUTHOR=Gao Peike , Li Guoqiang , Li Yanshu , Li Yan , Tian Huimei , Wang Yansen , Zhou Jiefang , Ma Ting 

TITLE=An Exogenous Surfactant-Producing Bacillus subtilis Facilitates Indigenous Microbial Enhanced Oil Recovery

JOURNAL=Frontiers in Microbiology

VOLUME=7

YEAR=2016

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2016.00186

DOI=10.3389/fmicb.2016.00186

ISSN=1664-302X

ABSTRACT=<p>This study used an exogenous lipopeptide-producing <italic>Bacillus subtilis</italic> to strengthen the indigenous microbial enhanced oil recovery (IMEOR) process in a water-flooded reservoir in the laboratory. The microbial processes and driving mechanisms were investigated in terms of the changes in oil properties and the interplay between the exogenous <italic>B. subtilis</italic> and indigenous microbial populations. The exogenous <italic>B. subtilis</italic> is a lipopeptide producer, with a short growth cycle and no oil-degrading ability. The <italic>B. subtilis</italic> facilitates the IMEOR process through improving oil emulsification and accelerating microbial growth with oil as the carbon source. Microbial community studies using quantitative PCR and high-throughput sequencing revealed that the exogenous <italic>B. subtilis</italic> could live together with reservoir microbial populations, and did not exert an observable inhibitory effect on the indigenous microbial populations during nutrient stimulation. Core-flooding tests showed that the combined exogenous and indigenous microbial flooding increased oil displacement efficiency by 16.71%, compared with 7.59% in the control where only nutrients were added, demonstrating the application potential in enhanced oil recovery in water-flooded reservoirs, in particular, for reservoirs where IMEOR treatment cannot effectively improve oil recovery.</p>