清洁压裂返排液复配驱油体系的构建及性能评价

Construction and Performance Evaluation of Surfactant Flooding System Based on Clean Fracturing Flowback Fluid

王 欢 由 庆 韩 坤 刘逸飞 方吉超

WANG Huan YOU Qing HAN Kun LIU Yifei FANG Jichao

针对现场压裂返排液中部分单一体系再利用效果不明显的问题， 通过考虑阴、 阳离子表面活性剂复配具有 协同效应的特点， 构建了一种基于清洁压裂液返排液的表面活性剂复配驱油体系， 通过分析体系降低界面张力 性能、 乳化性能， 优选了最佳的复配体系配方 0.2% RSH-2+0.012% AOS， 并评价了该复配驱油体系提高采收率效 果。结果表明， 纯返排液体系在质量分数 0.02%～0.5%范围内仅可将油水界面张力降低至 10-1 mN/m数量级， 而 0.2% RSH-2+0.012% AOS复配体系可降低油水界面张力至 10-3 mN/m超低数量级； 同时， 该复配体系乳化性能优 良， 油水比 1∶1的乳状液在静置 10 h后的析水率仅 30%。该复配体系在渗透率 0.0025 μm2的岩心中吸附性能优 良， 注入 124.5 PV时吸附达到动态饱和， 动态吸附量为 7.52 mg/g， 水驱后表面活性剂的滞留量只相当于动态饱和 吸附量的 1/4～ 1/3。该复配驱油体系具有较强的提高采收率能力， 在水驱基础上可提高采收率 11.8%， 能满足低 渗透油藏压裂后进一步提高采收率的要求。图 9参 25

Aiming at lower oil recovery increment of some clean fracturing flow-back fluid used in simple system， a method using the synergistic interaction between anionic and cationic surfactants was established to realize the reutilization of clean fracturing flow-back fluid in surfactant flooding， based on fundamental performance evaluation of flow-back fluid. The interfacial tension behavior， emulsification ability， adsorption behavior and enhanced oil recovery efficiency were studied systematically in laboratory. The results showed that the effective recipe of oil-displacing compound system was 0.2% RSH-2 + 0.012% AOS. The oi/water interfacial tension could only be lowered to 10-1 mN/m with single flow-back fluid， but could be further lowered to 10-3 mN/m through adding AOS with concentration 0.012%. The system had excellent emulsification performance， the water separation rate of the emulsion with oil-water ratio of 1∶1 was only 30% after 10 hours. Meanwhile， the dynamic retention amount was about one fourth to one third of the dynamic adsorption（about 7.52 mg/g） . The physical model experiments indicated that the oil recovery value could be enhanced 11.8% under optimal injection project， which confirmed its excellent performances on further enhanced oil recovery for low-permeability reservoirs after fracturing treatment.