Mechanism Of Microbial Enhanced Oil Recovery

A large number of production wells in oil fields located in east parts of China has already entered into the high water cut, and it now confronts with the difficulty and great pressure in such aspects as difficult exploitation, high cost and low recovery. MEOR (microbial enhanced oil recovery) has some characteristics such as abroad application, simple technics and good benefits compared with other traditional tertiary EOR technologies. It becomes the favorable EOR method. Its application and development will play a vital rule in crude oil increase and petroleum industry sustainable development of our country.The thesis was supported by National Natural Science Foundation of China (grant: 59974014), Sci. & Tech. Innovation Foundation for Youth in CNPC (grant: [1999] No39) and key Sci. & Tech. project of Dagang Oilfield Company (grant: 99KG05-05).The content of this thesis was divided into four parts: the first part is literature summarization; the second part is microbial metabolites and biological effect; the third part is research of physical simulation of MEOR; the last part is conclusion.For the aim at field technical problems and the heart theory, mechanisms of microbial waterflooding used thermophilic-facultative bacteria utilizing hydrocarbons as sole carbon-source have been firstly studied. It covers the physicochemical and biochemical process of bacteria with crude oil, the effect of microbial metabolism and metabolic products on interfacial performance, the growth and migration of bacteria in porous medium as well as contributive metabolites on oil recover. The primary contributions of this research are:1. For the first time, a systematic method for studying the mechanism of microbial waterflooding has been established, which was a difficult problem in the regarding field.2. A hypothetical structure of Rhamnolipid metabolized by microorganism N80 has been suggested.3. Components of metabolic products related to microorganisms used thermophilic-facultative bacteria utilizing hydrocarbons as sole carbon-source were outlined and a new model for the contribution of MEOR of metabolites has been developed.4. By adding the molecular sieve to cavity at chromatogram, series results of crude oil before and after degradation have been investigated systematically, including freezing point and viscosity.5. It is revealed in half-quantitative about microorganism "in situ growth" effects and wettability on interfacial performance in MEOR. A micro-model of oil film denudation was developed.6. The law of growth and migration of bacteria in porous medium has been found. Build the new methods of mechanism of MEOR. These methods provided a evaluation system for MEOR efficiency research.The results of this thesis will definitely provide a support for development of novel bacteria species and application of microbial waterflooding with both theoretical and technical support; they will also play a vital role in industrialization of microbial enhanced oil recovery in our country. The research results in this thesis have already used to design MEOR field trials of Guan-69 block in Dagang Oil Field, the field trials are carrying on in Guan-69 block now.