Study On The Applicability Of Low Salinity Water Flooding In Bohai B Oilfield

Water-flooding is a most economical and feasible development way.It is widely used in various oil fields in China.Currently,Bohai B oilfield is the same as other oil fields on offshore which injection water is mainly produced sewage,seawater and mixed water injection of effluent.However,the amount of produced sewage is far from insufficient for development,and more injection water needs to be added.In addition,mixed injection water is highly mineralized and easy to corrode pipelines.Meanwhile,it has high requirements for equipment and poor economic efficiency.According to literature reviews,many studies have been found that low salinity water can increase crude oil recovery.Thus,low salinity water is adopted as injection water in Bohai B oilfield to improve oil field status and increase oil field recovery.Low salinity water flooding means the salinity of the injected water contains total dissolved solids of low concentration,which is controlled to be under 5,000mg/L.To study the applicability of low salinity water-flooding in Bohai B oilfield,the range of applicable mineralization and the mechanism of increasing oil recovery,the following research is done in this paper:1.Cores were prepared according to the specific conditions of the Bohai B Oilfield.In order to study the effects of low salinity water flooding on enhanced oil recovery and the effect of clay minerals on recovery,measurement of relative permeability curve and low salinity waterflooding laboratory experiments were carried out.Considering the influence of clay minerals,the effect on increasing oil recovery by injection of water with low salinity is studied,and the applicability of low salinity water injection in Bohai B Oilfield is validated.2.By changing the composition and concentration conditions of salinity water,the change rules of Zeta potential and wettability of different rock mineral surfaces under different brine conditions were studied.At the same time,the effect of mineral surface charge on the wettability of mineral surface was also analyzed.3.The Zeta potential value and wettability of rock minerals under different salt ion composition and concentration conditions obtained from mathematical statistics are compared with experimental data.It is proved that the mechanism of low salinity water injection in Bohai B Oilfield is mainly to improve the recovery factor by changing the thickness and wettability of the double electric layer,the mechanism conforms to the addition rule.Finally,the mineralization of low salinity water injection in B oilfield on Bohai is approximately 20%of the formation water combined with all the experimental data.