Screening, Identification And Performance Of Oil Recovery Microbes Study

Microbial enhanced oil recovery (MEOR) is a technique to utilze microorganisms and their metabolic products to improve the recovery of crude oil from reservoir rocks. Bacteria are the only microorganisms that have been proposed for enhanced oil recovery process. They are small in size,grow exponentially and tolerate dicky environments such as: high temperature ,high water salinity and high pressure.They can enhance oil recovery by producing metabolic compounds such as gases, acids, surfactants and polymers. In this study, bacteria strains were isolated and their capabilities for crude exploitation were inverstigated.Three facultative anaerobic bacteria strains DY-32, RD18 and YD2 were isolated from oil-contaminated wastewater in Daqing oilfield . According to the studies on morphology, physiology, biochemistry, and 16S rDNA sequence, the strain RD18 was identified respectively as Pseudomonas aeruginosa, and strains DY-32 andYD2 were identified respectively as Bacillus subtilis.The toleration abilities of two strains RD18 and YD2 to temperature and salinity and the utilization and change of crude oil were researched. The results indicated the two strains could grew well in glucose media in the temperature range of 30℃-40℃, and they could grew using crude oil as single carbon source and reduced oil viscosity. The toleration abilities of B. subtilis YD2 to high temperature was better than P. aeruginosa RD18 and could grew at 40℃-45℃. B. subtilis YD2 have higher oil degradation rate than RD18 at most temperature conditions, and it have the highest oil degradation rate(15.6%) at 40℃. Whereas P. aeruginosa RD18 is the best in the ability of oil viscosity reduction and it have the highest oil viscosity reduction rate(37.52%) at 40℃. The salinity could influenced obviously the growth, oil degradation and oil viscosity reduction of the two strains and high salinity is a restrictive factor. The optimal salinity was 2%, and strain RD18 have the highest oil viscosity reduction rate(38.5%) and YD2 have the highest oil degradation rate(19.2%) at 2% Nacl. The optimal test were done to find the the best kinds and dosage of nitrogen source for seeding media. The results showed that 0.05% of yeast extraction is optimal. To strain YD2, the 0.1% of cottonseed powder is also fit. The optimal test of nitrogen source for oil degradation and oil viscosity reduction media showed the addition of inorganic nitrogen source could not improved the oil degradation of two strains, but the addition of urea could improved slightly the oil viscosity reduction of strains RD18 and YD2.