Mechanism Of Microbial Enhanced Oil Recovery In Daqing Oilfield

The concept of Microbial Enhanced Oil Recovery (MEOR) was advanced in the 50's of last century. Up to now, almost thirty countries in the world have done related researches and pilot trials. It is regarded as"one of the EOR technologies with the best future"because of such advantages as low cost, high adaptability and no harm to the reservoir, environment-friendly and so on. Both the laboratory study and field tests show that MEOR will play a more and more important role in the sustainable development of a mature oil field.The study aims at the conditions of Daqing oilfield, and considers the key problems of the MEOR. The characterization and research methods of microorganism were established by a traditional, modern instrumental analysis and chemical analysis methods. On this basis, the laboratory studies and the pilot trial of microorganism flooding were conducted and finally acquired a good result.A method is established here to study microbe flooding, via which the oil recovery bacteria could be attained, as well as the nutrition formulation and the technology parameter, which are essential for the microorganism flooding.The research method for microbial chemiotaxis was established. The motorial phenomena and processes of chemotaxis, the principle and method of activation were deeply studied. The microbial chemiotaxis of different initial bacteria concentration and different time was observed. At the same time, a large number of video for characteristics of bacterial chemo taxis by video capture system. Microbial chemiotaxis and adhesion were researched. The motorial phenomena and processes of chemotaxis, the principle and method of activation were deeply studied. The regulating method of different microbial chemiotaxis has been validated. Firstly, the microbial chemotaxis movement was promoted through the change of molecular signals; secondly, the proliferation of crude oil to the aqueous phase through the carrier.The influence of enzyme and genes on it was studied. The correlation between signal protein and chemiotaxis was proved by mobility capabilities and mutant gene cloning experiment.The metabolic pathway of docosane and fluorine, which degraded by microorganism, were determined by identification of intermediate metabolites and examination of isotope labeled metabolin. According to structural identification of intermediate, docosane was metabolized by microorganism in the form of terminal oxidation and generated docosanol, then further oxidized to acid, and underwentβ-oxidation process, generated stearic acid and hexadecanoic acid.There were two metabolic pathways in Fluorene degradation: (1) 9-fluorenone was generated by 9 site 2 step mono-oxygenation. (2) By 3, 4-dioxygenase, open-loop, and continuous two-step oxidation, (E)-3-(2-hydroxyphenyl) acrylic acid was generated after oxidative decarboxylation, oxidative ring cleavage reaction, in which polycyclic aromatic hydrocarbons were decarboxylation degradated byα-oxidation. The microbial degradation pathway of alkanes and aromatic hydrocarbons was further verified by the analytical results of polar oxygenated compounds in crude oil.Aiming at these phenomenas such as the nature of crude oil got worse after microbial degradation, the viscosity increased, rheology reduced, the process and degree of degradation were needed to control . After treatment, we had acquired good effect.The lab research and pilot test of the microbial enhanced oil recovery were guided by mechanism research. The microbial huff and puff injection trials of the 93 test wells had been carried out in Chaoyanggou, Pubei, Xingnan and Gaotaizi oil field. The microbial flooding field test of 2 injection and 10 extraction was conducted in Block 50 in Chaoyanggou oilfield. The total success rates of huff and puff injection of microorganism was 74.3%. The average increasing oil amount of single well was 143t, and the cumulative incremental oil was 12.5 thousand tons. 8 out of 10 wells showed significant oil production response. The per-month produced fluid increased from 957t to 1456t in the test area, water cut decreased from 46.8% to 40.3%, per-month oil production increased from 361t to 843t. Considering decreased factors, the total incremental oil is about 14 thousand tons.MEOR has been implemented in Daqing Chaoyanggou oil field and so far attained response of oil production and water decrease. The study performed here is specifically based on the characteristics of the Daqing reservoirs, nevertheless, the conclusions arrived at in this dissertation show the success and great potential of MEOR both in theory and in technology. It is of great significance not only to the application of MEOR in Daqing oil field but also to those oil fields with similar features like Daqing oil field.