The Study Of Reducing Injection Water Pressure And Improving Injection Capcity Of High Pressure Water Injection Wells Of Chang8Reservoir In Huanjiang Oilfield

Natural elastic energy of low permeability reservoir is generally small in our country. Flood is the most common exploitation way to maintain the producing energy and increase ultimate recovery of reservoir. In the present and the future for a long period, the flood development will continue to be the main form of oilfield development.However,the injection pressure of the injection wells always rise year by year,some injection wells’ pressure rise so rapidly that injection wells can not reach the quantity of injection,which seriously influences the effect of oilfield water injection development.Huanjiang oilfield encountered such a problem in the process of water injection development.Therefore, in order to solve the problem,this paper was make The study of reducing injection water pressure and improving injection capcity of high pressure water injection wells of Chang8reservoir in Huanjiang oilfield.First of all, we get to know the original states of the reservoir by means of the conventional core analysis,whose states mainly include these aspects:lithology,mineral composition,pore distribution,core permeability,cement composition,clay content and so on.Then we learn about the potential damage factors of the reservoir; Based on this factors, we find out the sensitivity degree of velocity sensitivity, water sensitivity, salt sensitivity, acid sensitivity by the experiment on core sensitivity, the results show that poor reservoir property is one of the causes of high pressure in Huanjiang oilfield of Chang8reservoir. Secondly,we do the experiments of water quality analysis of injection water and formation water and then do the test on the compatibility of injection water and formation water,the results show that the incompatibility of the formation water and injected water is the main cause of high pressure.Then, based on the study of reservoir property and reservoir flow properties, and combined with the present Huanjiang oilfield injection-production technology, this paper summarizes the causes of high pressure of water injection wells. Finally, according to the causes of high pressure of water injection wells to do the research about the acid fracturing system, the paper selects acid formulation and acid additive which appropriate Huanjiang oilfield, and makes the effect evaluation.