新型EOR方法：低矿化度水／CO2交替注入法——海水驱后的低矿化度水驱通过提升润湿性改造效果来提高采收率：注入CO2将碳酸盐岩和砂岩的润湿性向亲水性转变，使采收率进一步提高

本文提出了一种用于提升低矿化度水驱经济效果的新型提高采收率（EOR）方法，试验时测量了最小混相压力、界面张力和接触角．岩心驱替试验设计为海水驱＋低矿化度水驱＋连续注入CO2。结果表明：海水驱后的低矿化度水驱通过提升碳酸盐岩润湿性改造效果来显著提高采收率，在低矿化度水驱后注入CO2使碳酸盐岩和砂岩的润湿性向亲水性转变，进一步提高了采收率；低矿化度水中CO2较高的溶解度是残余油动用量增加的主要原因。为了使注CO2的成本最小化以及达到最佳波及效率，建议现场应用情况下使用低矿化度水／CO 2交替注入EOE方案。

Low salinity water-Surfactant-CO_(2) EOR

Coreflood,interfacial tension(IFT),contact angle,and phase behavior measurements were performed to investigate the viability of a hybrid of low-salinity water,surfactant,and CO_(2) flood enhanced oil recovery(EOR)process.Low-permeability carbonate reservoir cores were aged for eight weeks at reservoir temperature and pressure.Coreflood and contact angle between oil droplets and core surface measurements were performed.Additional contact angle measurements on sandstone and shale cores were also performed.The coreflood sequences were seawater flood,followed by low-salinity water flood,followed by surfactant floods until residual oil saturations to each flooding sequences and finally CO_(2) injection.Coreflood in low-permeability carbonate cores show that the hybrid EOR process produces incremental oil up to twenty-five percent beyond seawater flooding.Contact angle measurements on carbonate,sandstone and shale cores indicate that wettability alteration and IFT decrease are the main oil-mobilizing mechanisms in the hybrid EOR process.The hybrid EOR process mobilizes part of the residual oil because:(i)low-salinity brine improves wettability towards hydrophilic condition favorable for surfactant flooding;(ii)surfactant in lowsalinity water solubilizes some of the remaining oil as Winsor type II
microemulsion and lowers IFT between oil and water;and(iii)CO_(2) will follow surfactant to mobilize more of the remaining oil in the wettability-improved condition.