Study On Scheme Optimization And Evaluation Methods Of Original Microbe Flooding In Sa-Nan Oilfield Transition Belt

With the problem of bad oil flooding effect in Sa-Nan oilfield, original microbe flooding laboratory experiment study is brought into production.The study results show: oil layer contains bacterium which is suitable for original microbe flooding such as hydrocarbon degradation bacterium, producing methane bacterium and nitrate deoxidization bacterium and so on. The nutriment formula verified by the study can effectively restrain the growth of detrimental bacterium and arouse the growth of beneficial bacterium. The growth curves of microbe at diverse nutrient solution concentration conditions are measured. In the range of experimental concentration,nutrient solution concentration has no effect on the growth and propagation of microbe.The microbe that degrades the oil can grow and propagate in the given nutrient solution. As the nutrient solution concentration increases, the oil viscosity reducing ratio improves. In the given nutrient solution condition, the selected microbe can produce organism surface active agent. But it produces a few amount of surface active agent. The oil-water interfacial tension changes little.Results of injected original bacterium flooding experiment show: as the amount of original microbe increases, the enhanced scope of recovery improves. When the injection rate of original bacterium is 0.2 and 0.3PV respectively, the enhanced oil recovery is 4.95 and 6.08 percentage point respectively. Under the same total amount condition, the slug injection and continuous injection manner of nutrient solution have little influence on the enhanced scope of recovery.Based on the study of geology character of original microbe experimental area, the fine reservoir numerical simulation model of original microbe experimental area in Sa-Nan transition belt is established. At the same time, water flooding history match is carried on and the match error is less than 1.6%, showing that the established model is basically the same as the real model. Remaining oil distribution study show: the recovery degree of Sâ…¢is 42 percentage. Its development effect is good and the remaining oil saturation is low. The recovery degree of Sâ…¡is 27.9 percentage. Its development effect is the worst and the remaining oil saturation is relatively high.Numerical simulation study results of single factor influencing microbe flooding show: as the activator concentration rises,the enhanced recovery value increases. But after the concentration increases to some extent, the enhanced recovery scope will decrease. As the injection period increases, the enhanced recovery value decreases. The bigger the injection slug is, the more enhanced recovery value is. After the injection slug increases to a given extent, the enhanced recovery scope decreases.With crosscut design method, using the activator concentration, injection period and injection PV number as parameters, 16 sets injection schemes of three parameters and four levels are established. Based on the present remaining oil distribution data and laboratory experiment data, original microbe flooding numerical simulation study and optimize scheme design are carried on. Using fuzzy comprehensive evaluation model, taking recovery and economic assessment constraint condition into account, the results are analyzed, showing that the best scheme is activator concentration of 5 percentage, injection period of 30 days and injection rate of 0.3PV.