Investigation of Indigenous Microbial Enhanced Oil Recovery in a Middle Salinity Petroleum Reservoir

Culture-based techniques were applied to analyze the diversity of indigenous microbial communities in the Qinghai middle salinity petroleum reservoir (QH-MSPR). The results of the most probable number (MPN) method indicated there was an abundance of indigenous microbes (10(5)-10(6)MPN/ml). Two isolations (BIOS682) from the QH-MSPR were identified as Brevibacillus agri and Brevibacillus levickii. The study showed that BIOS682 enhanced the degradation rate of Huatugou crude oil. The viscosity and freezing point of crude oil after treatment by BIOS682 were all decreased. The results of TLC and FTIR spectrum analysis of the biosurfactant produced by BIOS682 indicated that it was identical to that of lipopeptide. The core-flooding tests showed that the incremental oil recoveries were 7.05-10.15%. Thus, BIOS682 may provide a viable application of microbial enhanced oil recovery (MEOR).