为提高泡沫驱原油采收率，通过室内岩心驱替实验研究了预注低矿化度水再进行泡沫驱的驱油效果以及 原油组成及注入水矿化度对该驱替方式驱油性能的影响。研究结果表明，低矿化度水驱能反转岩石润湿性，将 油湿岩石改变为水湿岩心。采用矿化度130000 mg/L的模拟地层水水驱至98%后注入2 PV的 低矿化度水（矿化 度2784 mg/L）再按气/起泡剂溶液体积流量1∶1交替注入氮气和质量分数为0.1%的起泡剂溶液2 PV，泡沫驱最 高封堵压力为0.242 MPa，低矿化度水驱后泡沫驱比水驱提高采收率14.20%。低矿化度水驱与泡沫驱能产生协 同作用，低矿化度水驱后续泡沫驱过程生成了稳定泡沫，提高了泡沫在多孔介质中的封堵能力，从而大幅度提高原 油采收率。随着原油酸性组分含量和注入水矿化度的降低，岩心亲水性会更强且泡沫驱性能更好。
In order to improve the oil recovery of foam flooding，the oil-flooding effect of low salinity water pre-flooding during foam injection was analyzed by indoor core-flooding experiments. The effect of crude oil composition and injected water salinity on oil displacement performance was investigated. The experimental results showed that the wettability of crude-oil aged oil-wet core appeared to be water wetting characteristic by low salinity water flooding. The core was flooded by the simulated formation water with a salinity of 130000 mg/L until the water cut was 98%，and then 2 PV of low salinity water with the salinity of 2784 mg/L was injected，and then 2 PV of nitrogen and foaming agent solution of 0.1% mass fraction was injected alternately in which the volume flow ratio of the gas/foaming agent solution was 1∶1. The maximum plugging pressure of foam flooding was 0.242 MPa. Enhanced oil recovery by up to 14.20% was observed with foam flooding after low salinity water flooding compared to water flooding. Low salinity water flooding and foam flooding could have a synergistic effect. The subsequent foam flooding process after low-salinity water flooding generated stable foam，which improved the foam's plugging ability in porous media，thereby greatly improving oil recovery. As the acidic contents of crude oil and the salinity of injected water decreased，the rock would be more hydrophilic and had better foam flooding performance.