Study On Variation Of Indigenous Microbial Community And Enhanced Oil Recovery Under Simulated Reservoir Condition

In order to make the regulation on microbial community more effective in oil reservoirs, and to improve the microbial displacing oil theoretical based on community principles, indigenous microbial flooding experiments were carried out based on the indigenous microbial of Zhongyi block Ng3 in Shengli Oilfield. This paper studies the variation of microbial communities in different activating conditions and confirms the mainly influence factors. This will provide theoretical basis for the effectiveness of microbial regulation reservoirs, and lay the foundations for the full use of microbial enhanced oil recovery technology advantage, so that the performance of MEOR in oil fields could be improved significantly. The main results were summarized as follows:1. The static activation effect of carbon source, oxygen and porous medium on microbial population were studied by simulating zhongyi block Ng3 reservoir temperature and pressure environment of Shengli oilfield. The results show that the growth cycle, community structures and metabolic activities were significantly influenced by the carbon source. The common carbon sources such as glucose, corn starch hydrolysates and wheat starch, etc. can effectively activate reservoir microbial community and promote indigenous metabolism. The content of dissolved oxygen in activators significantly can influence the microbial community structure. A increase in the content of dissolved oxygen in the activators will raise the content of surface active substances of produced water, which reduce the surface tension of medial and improve the potential of oil emulsification ability. The space system of porous reservoir formation can provide advantages for various microbial activities. The permeability of porous media influences the microbial community structure obviously. With the increase of microbial growth environment permeability, microbial diversity and quantity are increased.2. The on-site implementation process was simulated by continuously flooding experiments . Displacement effect, community structure and metabolites were analyzed in this process. The results show that the indigenous microorganisms were activated in the short term of physical simulation experiments, and keep 106cells/mL for a long time. Attenuation of microbes appear obviously in continuous water flooding around 15 days, and can be used as the basis for optimizing on-site injection technology. The used activation system of corn starch hydrolysates can make the produced water rising trend restrained obviously, and show good water controlling oil increase role. Through the microorganism and metabolism product distribution for field test of cognition, so that we could know and optimize microbial flooding better in field.3. Porous media has a strong retention effect in microbial cells. The presence of oil-water interface will increase the retention of microorganisms to further clarify the microbial cells enriched in the oil-water interface. Microbial cells can significantly reduce the permeability of porous media, which has the feasibility of enhanced oil recovery. With the injection recovery, the majority of viable cells distribute in the near the entrance of corebarrel. The number and diversity of microbial have a slight decrease in the direction along the injection recovery.