Feasibility Study On Enhanced Oil Recovery By Low Water Mineralization In XM Oilfield

At present, as the exploitation of oil fields, water injection has been an important method to enhance oil recovery, especially for the low permeability oilfields. Injecting water can increase the formation pressure, supply formation energy, besides, injection water can displace crude oil and prompt the wells produce more crude oil, thus enhancing oil recovery. The nature elastic energy of low permeability oilfields in our country is generally small, and most of these oilfields have taken the water injection development method to keep the pressure and supply the formation energy. However, as the time of injecting water becomes longer, the effect of water injection becomes worse gradually, even brings some adverse effects. For example, the underground reservoir was destructed, the moisture of production wells becomes high, even up to90%; on the other hands, the salinity of injection water is so high that causing the wellbore and the bore hole scaling etc. which is unfavorable to oil production. When generating these results, which cannot bring benefits to the oil fields, but decline the production yield, at this time, water injection plays a contrary effect.In addition to the geological characteristics and reservoir characteristics of the oilfield, the most important condition which directly determines the development effect is "inject sufficient and favorable water". Injecting sufficient water is the water injection amount should be adapt to that of the production liquid, and keep the formation pressure in a reasonable level. Injecting favorable water means enhancing the efficiency of water drive reservoir, improving the water injection degree of the geological reserves, which and achieve better development results. Injecting low salinity water is an effective method to enhance oil recovery.This paper is mainly about the water injection problems of Fuyang reservoir of XM oilfield, which is a low porosity, low permeability and strong heterogeneity reservoir. Now, it is difficult for the injection wells to inject water, the injection pressure is high, the oil wells are not effect and the production is low. About these problems, proposing a new water injection program, low salinity water injection, which is a method to decrease the salinity of the injection water. Normally, the salinity is below5000mg/L. At present, there is no depth study about low salinity water injection in our country. In this paper, through a lot of research of low salinity water injection at home and abroad, including experimental and theoretical literature, have a comprehensive analysis of the mechanism of low salinity water injection to improve oil recovery. On this basis, make full use of reservoir simulation technology to compare the high-salinity and low salinity water injection development effect, and validate that the low salinity water injection can improve the waterflooding effect of oilfield. Finally, for the actual development of XM oilfield, put forward a reasonable low salinity water injection project.