Abstract：In order to study the feasibility of enhancing oil recovery rate in Qinghai oil field with hypersalinity, the composition of indigenous microorganism community was analyzed by MPN counts, the nutrient packages for emulsification were evaluated, the acid production was studied and the sequence of 16S rDNA and the saturated hydrocarbon of oil samples were analyzed. Results show that the main microbial populations in the reservoir are saprophytic bacteria, hydrocarbon-oxidizing bacteria, fermentative bacteria and nitrate reducing bacteria. The indigenous microorganisms can use nutrition added for emulsification through acid production; its cell concentration can reach 107cells/mL, and the surface tension is reduced from 57.44mN/m to 38.5mN/m. The pH value of the fermentation liquor with nitrogen source is decreased from 7.19 to 6.56, and the pH value of the fermentation liquor added with carbon and phosphorous source remains unchanged, so the optimal nutrient was the nitrogen source (0.1% yeast and 0.1% peptone), which was used for all subsequent experiments. The total DNA was extracted, 16S rDNA universal primers were applied for gene amplification, and the results were sequenced and analyzed. The species isolated were confirmed to be Bacillus sp. and Halomonas sp.; the saturated hydrocarbon was catalyzed selectively (C11~C20, C28, C33), which exhibited a great potential to enhance oil recovery rate.
2011, Vol. 29 
