Study on Stratified Water Injection Technology with Low Salinity in Tight Lithologic Reservoir in Yanchang Oilfield
Studies have shown that the injection of low salinity water(LSW)has the potential to enhance oil recovery.In this paper,the adsorption of silica nanoparticles(NPs)on sandstone and their effect on the fluid/rock interaction during LSW flooding were investigated.In isothermal static adsorption experiments on sandstone surfaces,nanoparticles exhibited higher adsorption affinity than kaolinite on quartz surfaces.As salinity increased,the adsorption capacity of nanoparticles increased.In the dynamic adsorption experiment,about 0.033 g of nanoparticles and tracer(about 0.13 g of lithium chloride)were injected,and the irreversible adsorption rate of NPs in the core displacement process was estimated to be about 35%,while the desorption rate of flooded cores was about 21.2%.The results of mass balance analysis showed that pH value had a certain effect on the adsorption/desorption process of nano-silica,and the increase of alkalinity was conducive to the desorption of nanoparticles.Compared with LSW and NP flooding alone,the adsorption of nanoparticles on the mineral surface during the LSW and NP composite flooding process reduced the dissolution of minerals.The surface force estimation showed that the combination of LSW and NPs reduced the repulsion between the mineral particles.The synergistic effect of combining the two technologies of LSW and nanoparticles reduced the probability of formation damage in sandstone reservoirs.
Oil floodingWater injection of geosalinityNanoparticlesEnhanced oil recovery
万方数据
维普
