Adaptability Evaluation And Water Flooding Scheme Design Of Low-Salinity Water Flooding In Chang 6 Reservoir Of Wuliwan

Compared with conventional water flooding,low salinity water flooding can change reservoir wettability and effectively reduce residual oil saturation,thereby improving the oil displacement efficiency of injected water,so it has been widely used in oil fields at home and abroad.However,the mechanism of low salinity water flooding is complex and requires high compatibility with reservoirs.Therefore,it is necessary to demonstrate and apply the applicability of different reservoir characteristics.Firstly,based on the reservoir characteristics of Wuliwan Chang 6 reservoir,the applicability of the reservoir with low salinity water flooding is analyzed.The results show that the reservoir is suitable for low salinity water flooding.Then,considering the influence of salt components,a mathematical model of low salinity water flooding is established,combining with three-phase mass conservation equation,the displacement law in porous media is analyzed.The simulation results show that the oil displacement efficiency of low salinity water injection is obviously higher than that of high salinity water.Secondly,the applicability of low salinity water displacement method to improve oil displacement efficiency in Wuliwan Chang 6 Oilfield is demonstrated through laboratory experiments,relative permeability curve and water displacement efficiency experiments.Moreover,the critical salinity range of low salinity water displacement is determined through reservoir sensitivity evaluation and oil displacement efficiency experiments.Finally,using reservoir numerical model to simulate different salinity water flooding schemes,the results show that there are differences in oil displacement efficiency between different salinity water flooding schemes,and within a certain range,the lower salinity,the higher oil displacement efficiency;At the same time,according to the salinity gradient design,the reasonable threshold value of low salinity water flooding in Wuliwan Chang 6 Oilfield is determined,and based on the reasonable threshold value,we developed a low-salinity water flooding scheme,which is suitable for the reality of Wuliwan Chang 6.The low salinity water flooding scheme with reservoir characteristics provides important reference value for field application.