Screening Of Microbial Strains And Evaluation Of Microbial Enhanced Oil Recovery In Dingbian Block

Microbial enhanced oil recovery(MEOR)utilizes bacteria and their metabolites products to improve the recovery of crude oil from reservoirs.The mechanism of MEOR is to decrease interfacial tension in the oil-water-rock system,improve mobility ratio of the reservoir fluids,increase displacement efficiency and conformance factor,decrease crude oil viscosity by biological degradation,etc..The microbiological activities take place in a geological environment such as a reservoir,the petroleum geological,geochemical,mineralogical,hydrological,reservoir fluids components and the interaction between the geological and biological components of the environment hanve profound effects on biological growth,activity and metabolite.The screening of microbial vaccines should fully take account of the environmental conditions present in a given reservoir.This paper presents a group of screen standards for MEOR in oil fields.According to the reservoir formation condition of the test field,a primitive strain releasing bio-surfactants,a primitive strain degrading petroleum hydrocarbon and an exogenous strain releasing biopolymer were separated and screened,and the three strains were identified.Then,the article researched the three strains of growth and metabolism in high salinity condition respectively,research showed that the three strains could adapt to a higher salinity,For different strains,the compatibility of nutrient medium was studied,the results proved that the three strains could nomally grow up and not influent each other in mixed nutrient medium.Finally,aiming at the special low permeability reservoir Dingbian Block of Yanchang Pereoleum Group,the problem of how to further enhance oil recovery after water flooding.Oil displacement experiment is carried in laboratory.By simulating reservoir conditions such as temperature 50 ? and so on,researched on the displacement effect of three microorganism S.M.P in the Dingbian natural core columns.Analyzed oil displacement mechanism of the three microorganism S?M?P through combining injection pressure and the recovery curve in the core.When mass concentration of microorganism M was 10%,slug size was 0.5 pore volum,recovery could reach 9%.The results demonstrated that microorganism M has a good adaptability for low permeability,micro-fractures fixed side block.