MEOR Study Of The Low Permeability Reservoir For Outer Skirts In West Daqing Oilfields

MEOR is a kind of tertiary recovery technique to improve recovery factor. The mechanism of MEOR is using its characteristic and metabolizing substance to degrade beak viscidity, remove wax and plugging, improve the oil fluidness and improve formation pressure, so as to improve recovery factor.The enzyme ,produced during the metabolize of the microbe, can crack the hydrocarbon and wax, can reduce the viscidity and freezing point, so as to reduce the flow resistance of the oil, to improve the oil fluidness ,thus improve output and recovery factor. Microbe can produce CO2, N2, H2 and CH4 during its metabolizing. All these gases can holding and improve formation pressure, and can dissolve in the oil, thus to reduce its viscidity, to improve the output. Microbe can produce some kinds of chemical substances, such as biology polymer, biology surface active agent, small molecule organic acid and good wine. When microbe injected into the water-oil displacement layers , its thalli and metabolizing substance can tune to deposit ,which having high plugging function and its seal off ratio can get to 99%. This is good for heterogeneity pool's effect of plugging and profile. And can improve the output and recovery factor. Biology polymer can control the mobility ratio of the high permeable sections, adjust injection profile, improve sweep area, improve recovery factor. One of its metabolizing substance---β—amrita polyvinyl sugar enzyme has good hydration for, is a effect kind of fracturing fluid gel-breaking.In order to improve the oil fluidness, reduce the pressure-loss of the area near the well, we have selected suitable microbe according to the geological and fluid characteristics of Oil Product NO.9 of Daqing Oilfield since 2001. Now, we have more than 80 kinds of microbes, including microbial vis-beaking, wax removal and plug removal, the second fracturing fluid gel-breaking. Analyzing the mechanism of MEOR, we used single well microbial treatment technology,which includes microbial vis-beaking, wax removal and plug removal, the second fracturing fluid gel-breaking techniques, and microbial flooding test. Oilfield testing got good effect. It can be taken for development of other low permeability oil field as a reference.