The Studing On The Mechanism Of Microbial Flooding And Analysis Of Microflora In Typical Reservoir

This paper mainly focuses on the discovering the primary aspects in microbial enhanced oil recovery (MEOR) technology, including distribution of microorganisms in the oil reservoir, structure of microbial community, microbial growth and metabolic activities under aerobic and anaerobic conditions in the porous media, microbial induced crude oil emulsification and viscosity-reduction mechanism.The results from this study can further contribute to the development and insight of MEOR technology.As for the distribution of microorganisms in the oil reservoir, on the basis of understanding the characteristics of different microbial consortia in the oil reservoir, three types of distribution model are classified, according to the potential of microbial stimulation: ⅰ) for those reservoirs of 60 ℃ and below, high quantity of microbe species ensures the MEOR application, ⅱ) for those reservoirs from 60 ℃ to 75 ℃, the quantity of microbe species exhibits certain potential for MEOR application, ⅲ) for those reservoirs of 75 ℃ and above, the microbial quantity cannot fulfill the MEOR application. The classification put forward a guiding significance for screening the reservoirs for MEOR.Most probable number (MPN) method and library of 16SrRNA clones method are employed to discover the microbial communities in both water-flooding and after polymer-flooding oil reservoirs in Daqing oilfield. The eubacteria are identified as Thauera, anaerobaeterium, Pseudomonas, Acinetobacter, Rhodococcus ruber and Enterobacter. The archaea belong to Methanosaeta, Methanospirillum and Methanosarcina. The biosurfactant-producing strain, Rhodococcus ruber RH-1, and an anaerobic methanogenesis community are obtained from the enrichment.Microscopic transparent model is used to study the microbial-flooding micromechanism of Rhodococcus ruber RH-1 and anaerobic methanogenesis enrichment. Sand package models are also carried out by aerobic bacteria and anaerobic enrichment to study the microbial growth, metabolites and the effect of crude oil emulsion simulation during the experiment. The main displacement mechanisms for Rhodococcus ruber RH-1 are hydrocarbon degradation, biosurfactant production and crude oil emulsification while the anaerobic enrichment shows that of methanogenesis ability.Based on the analysis of production fluid of field test, the microbial induced crude oil emulsification is carried out by analyzing the effects of crude oil type, microbial concentration and water cut. The microbial emulsion liquid phase diagram is established and the limit concentration and water cut are proposed, which provides a novel method for evaluation the microbial induced crude oil emulsification and viscosity-reduction.