针对高温高盐油藏研发了具有微观调控能力并可兼顾驱油效率的冻胶分散体软体非均相复合驱油体系,借助岩心流动实验和可视化实验,研究该体系特征及驱油机理。该体系由冻胶分散体和表面活性剂组成,适用于温度80~110 ℃、矿化度1×104~10×104 mg/L的油藏,具有低黏度、弱负电性、耐温耐盐的特点,能够聚结长大,使油湿表面润湿性发生反转,水湿表面润湿性减弱,高温老化后的界面张力仍小于1×10-1 mN/m。软体非均相复合驱油体系能够进入岩心深部对储集层进行微观调控,岩心渗透率级差越大,调控效果越好,其驱替效果明显优于表面活性剂驱油体系、冻胶分散体或聚合物-表面活性剂二元复合驱油体系。复合驱油体系在多孔介质中的调控行为有直接封堵、架桥封堵、吸附及滞留4种,其中的表面活性剂可强化复合驱油体系的深部运移和洗油能力,通过强化洗油机理、协同乳化机理、强化润湿反转及油带聚增机理提高洗油效率,冻胶分散体和表面活性剂的协同效应增强了复合驱油体系的驱替效率。图12参14
Considering high temperature and high salinity in the reservoirs, a dispersed particle gel soft heterogeneous compound (SHC) flooding system was prepared to improve the micro-profile control and displacement efficiency. The characteristics and displacement mechanisms of the system were investigated via core flow tests and visual simulation experiments. The SHC flooding system composed of DPG particles and surfactants was suitable for the reservoirs with the temperature of 80-110 ℃ and the salinity of 1×104-10×104 mg/L. The system presented good characteristics: low viscosity, weak negatively charged, temperature and salinity resistance, particles aggregation capacity, wettability alteration on oil wet surface, wettability weaken on water wet surface, and interfacial tension (IFT) still less than 1×10-1 mN/m after aging at high temperature. The SHC flooding system achieved the micro-profile control by entering formations deeply and the better performance was found in the formation with the higher permeability difference existing between the layers, which suggested that the flooding system was superior to the surfactants, DPG particles, and polymer/surfactant compound flooding systems. The system could effectively enhance the micro-profile control in porous media through four behaviors, including direct plugging, bridging, adsorption, and retention. Moreover, the surfactant in the system magnified the deep migration capability and oil displacement capacity of the SHC flooding system, and the impact was strengthened through the mechanisms of improved displacement capacity, synergistic emulsification, enhanced wettability alteration ability and coalescence of oil belts. The synergistic effect of the two components of SHC flooding system improved oil displacement efficiency and subsequently enhanced oil recovery.
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