Abstract
A novel Bacillus licheniformis strain (DM-1) was isolated from a mature reservoir in Dagang oilfield of China. DM-1 showed unique properties to utilize petroleum hydrocarbons and agroindustrial by-product (molasses) for exopolysaccharide (EPS) production under oil recovery conditions. The DM-1 EPS was proven to be a proteoglycan with a molecular weight of 568 kDa. The EPS showed shear thinning properties and had high viscosities at dilute concentrations (<1%, w/v), high salinities, and elevated temperatures. Strain DM-1 could degrade long-chain n-alkanes up to C36. Viscosity reduction test have shown that the viscosity of the crude oil was reduced by 40% compared with that before DM-1 treatment. Sand pack flooding test results under simulated reservoir conditions have shown that the enhanced oil recovery efficiency was 19.2% after 7 days of in-situ bioaugmentation with B. licheniformis DM-1. The obtained results indicate that strain DM-1 is a promising candidate for in situ microbial enhanced oil recovery (MEOR).
Highlights
A novel Bacillus licheniformis strain (DM-1) was isolated from a mature reservoir in Dagang oilfield of China
BNP29, a strain of B. licheniformis isolated from a German oil reservoir, can improve oil recovery efficiency by up to 22.1% after in-situ microbial treatment[13], and ZR3, an engineered strain constructed from a EPS-producing strain and a thermophilic strain, can improve oil recovery by up to 11.3% of the OOIP over water flooding after 7 days in-situ bioaugmentation[14]
After the first water flooding, bacterial culture and nutrient solution were injected to the cores, and the oil recovery efficiency increased by in-situ bioaugmentation with DM-1 was examined.The results revealed that for the nutrients flooding, 6.9% oil recovery efficiency was achieved, while for the in-situ test with strain DM-1 and nutrients (BH medium and 2% molasses), the recovery was 19.2% of OOIP
Summary
A novel Bacillus licheniformis strain (DM-1) was isolated from a mature reservoir in Dagang oilfield of China. Sand pack flooding test results under simulated reservoir conditions have shown that the enhanced oil recovery efficiency was 19.2% after 7 days of in-situ bioaugmentation with B. licheniformis DM-1. Partially hydrolyzed polyacrylamide and its derivatives are the most widely used substances in polymer flooding and have been used in a lot of oil fields for large-scale oil production[8,9]. BNP29, a strain of B. licheniformis isolated from a German oil reservoir, can improve oil recovery efficiency by up to 22.1% after in-situ microbial treatment[13], and ZR3, an engineered strain constructed from a EPS-producing strain and a thermophilic strain, can improve oil recovery by up to 11.3% of the OOIP over water flooding after 7 days in-situ bioaugmentation[14]
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