Study On Enhanced Oil Recovery By Ion Optimized Water Flooding In XX Oilfield

Ion optimized water flooding is the inheritance and development of low salinity water drive.By adjusting the composition and concentration of ions in injected water,we hope to get higher water flooding recovery.Conventional oilfield water injection is generally used for secondary oil recovery for the supplementary energy of the reservoir.However,according to a large number of studies done by foreign scholars on the mechanism of ion optimized water flooding,ion optimized water flooding mainly improves the reservoir wettability by diffusing electric double layer and multi component ion exchange,and further enhancing oil recovery.Ion optimized water flooding can make use of the existing injection production well pattern,reduce investment and do not need a lot of chemicals and complex ground treatment measures.It is an economical,environmentally friendly,easy to operate and potential new technology for oilfield development.Some oil fields in other countries have carried out field test of low salinity water flooding.Some oil fields have achieved good results.For example,BP has applied field experiments in Alaska's Endicott oilfield,and even enhanced recovery by 26 percentage points.The paper carried out study on enhanced oil recovery by ion optimized water flooding in XX oilfield,the focus of the research is on the three aspects of the optimization of the injection water system,the physical simulation test of water flooding and the numerical simulation.First,based on the study of Zeta potential in clay minerals,oil/water and water/rock interfaces,the injection water system is selected based on the theory of diffusion double layer and the thermodynamic theory of oil/water/rock interface.Secondly,aiming at the injected water system,a series of water drive physical simulation experiments were carried out for core flooding experiment,CT tomography experiment,sensitivity analysis and so on,and the most suitable ion optimized water for XX oilfield was selected.Finally,the numerical simulation of the optimized ion optimized water is carried out to evaluate the influence of reservoir heterogeneity,injection amount,injection rate and injection timing on enhancing oil recovery by ion optimized water flooding.The results show that if the disjoining pressure of the oil/water/rock interface system is positive value,the force between oil/water interface and water/rock interface is repulsion and the wettability of reservoir rock is more inclined to water wet.Conversely,if the disjoining pressure of oil/water/rock interface system is negative value,the force between oil/water interface and water/rock interface is attraction and reservoir rock is more likely to be oil wet.The ultimate recovery of low salinity water obtained by diluting 20 times and diluting 100 times of the formation water under the secondary oil recovery mode is equal to that of the tertiary oil recovery mode,ion optimized water flooding has the best injection time.The ion optimized water flooding can obviously enhance oil recovery under the secondary oil recovery mode and tertiary oil recovery mode,the lower salinity water obtained by 100 times the formation water dilution is the best to enhance oil recovery.The ion optimized water flooding is more suitable for the region with relatively weak heterogeneity in the longitudinal direction.In a certain range,the greater the injection amount and injection rate,the higher the recovery.The recovery in fiftieth years of low salinity water is injected when the water content is 80%by formation water flooding is apparently higher than that of when the water content is 95%by formation water flooding and secondary oil recovery mode of low salinity water flooding.