Screening And Study Of Microorganisms For Enhancing Oil Recover Apply In High Mineralization Reservoir

Microbial Enhanced Oil recovery is a tertiary recovery method which take advantages of the growth and metabolites and some other activities of the microorganisms in the oil reservoir to change the reservoir conditions and oil properties.The oil reservoir which this paper researched belongs to high salinity reservoirs. It could provide a efficient means to improve the oil output in further exploitation.14 high mineralization-tolerant strains were isolated from the oil-water and sludges sanples after enrichment.Three strains?3-2,Kl,t'? for oil recovery were screened by emulsification,surface active and Oil leaching experiments.After morphological and physiological and biochemical identification, t'was initially identified as Candida Albicans.According to morphological, physiological and biochemical characteristics and molecular identification,3-2 and K1 were identified as Bacillus subtilis and Klebsiella pneumoniae.The fermentation medium of strain 3-2 and t'were optimized.The best combination of carbon and nitrogen sources experimental results show:When using soluble starch and peptone as the carbon and nitrogen source of strain 3-2,the reducing rate of high water surface tension increased obviously.Strain t' still used the initial medium.With the surface tension of high water reducing rate after adding the same amount of fermentation broth as the response value, the proportion of components in medium were optimized by response surface methodology,the results show:when strain 3-2 fermentation culture medium group contained soluble starch 27.26 g/L, protein peptone 5.71 g/L, yeast extract 0.8 g/1, the surface tension of high mineralized water after adding fermentation broth reduced 55.63%, and the rate was much higher than the initial fermentation medium,while the amount of bacteria in the fermentation broth was also obviously increased.When strain t' fermentation culture medium group contained sucrose 27.18 g/L, ?NH4? 2HPO41g/L, yeast extract 5.0 g/L, rapeseed oil 15.35 g/L, the surface tension of high mineralized water after adding fermentation broth reduced 50.92%,while the amount of bacteria was also obviously increased.The high mineralization adaptability and other characteristics just like reduce high mineralization water interfacial tension, change the oil content,reduce pH,reduce solidifying point, reduce viscosity,change carbon distribution of the oil had been analyzed.The result indicated:these strains had a better growth in the high mineralized environment,after mixed culture the water surface tension decreases obviously.Three strains with better capabilities of reduce the freezing point and viscosity on crude oil, the effect of t'was the most obvious, after being degraded by t'the freezing point of crude oil and viscosity were decreased by 14.33% and 26.35%.The strains for oil recovery can degrade asphaltene in crude oil faintly,but can make good use of and degradation of saturated hydrocarbon, the degradation ability of saturated hydrocarbons is t'> 3-2> K1.With the characteristics of saturated hydrocarbon carbon number distribution and of parameter analysis of crude oiland residual oil after microorganism degradation indicates:strain t' can make the light component of crude oil content increased;strain 3-2 can degrade saturated hydrocarbons nC₂₉, nC₃₁ and nC₃₃;the effect of strain K1 of crude oil is not obvious.