Characteristics and Field Application of Bio-Surfactant Produced by Bacillus subtilis BIT-BS002

A bio-surfactant high-producing bacteria strain was isolated from heavy oil sample from Liaohe oilfield.It was identified as Bacillus subtilis according to its morphological,physiological,and biochemical characteristics and 16S rDNA sequence analysis and named as BIT-BS002.The bio-surfactant produced by BIT-BS002 was characterized by FTIR and TLC analysis,and its structure consists of a cyclic peptide sequence linked to a fatty acid.It could reduce the surface tension of cultured medium from 54.88 to 26.99 mN/m after cultured for 24 h under 50 ℃.The emulsion separation rate of kerosene and liquid paraffin after treated by BIT-BS002 were 100% and 94%,respectively.The results also showed the heavy oil viscosity reduction rate was 81.93%,and residual oil was recovered from sandstone cores over 14.75% compared to water flooding only.The field test of strain BIT-BS002 already achieved good results in MEOR huff and puff,and the oil recovery was 3.86 times more than before the construction.