Screening and performance evaluation of microbial enhanced oil recovery strains from shale oil reservoir
A strain of biosurfactant-producing bacteria Y2 was isolated from shale oil reservoirs.It was i-dentified by 16s rDNA gene sequencing.The strain's cultivation conditions were optimized and its stabili-ty was examined at different pH values,temperatures,and salt concentrations through surface/interface tension tests.The physicochemical properties of the biosurfactant produced by the strain were character-ized using FTIR and LC-MS analysis.The surfactant activity of strain Y2(Bacillus subtilis)was the best in the medium with glucose as carbon source and ammonium nitrate as nitrogen source.The surface ten-sion value of the Y2 strain was 27.61 mN/m,and its interface tension with shale oils JHW151 and JHW07121 were 0.062 mN/m and 0.047 mN/m,respectively.The surface-active agent produced by the strain was a mixture of C15-Surfactin and C16-Fengycin lipopeptides,which showed good surface activity stability in the range of 40～80℃and pH 1～11.However,the interfacial tension decreased with increas-ing NaCl concentration.It can be seen that the Y2 strain has good surface activity,which can effectively reduce the oil/water interfacial tension and improve the shale oil recovery,providing a potential and feasi-ble technical route for the efficient development of microbial displacement in Jimsar shale oil.
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