低渗透油藏表面活性剂/有机碱降压增注体系研究

Surfactant-Organic Alkali Decompression and Augmented Injection System in Low Permeability Reservoir

王增宝 王 静 仝 铭 武 凯 秦磊斌 吕慧轩

WANG Zeng-Bao WANG Jing TONG Ming WU Kai QIN Lei-Bin Lü Hui-Xuan

在50℃下，通过室内实验优选出一种化学降压增注体系，组成为：0.05%双子表面活性剂HA-1+0.1%乙醇胺MEA+0.1%甲醇。该体系可使油-水瞬时最低界面张力降至3.78×10-5 mN/m。考察了降压增注体系改变岩石润湿性的能力以及耐盐、耐温性能。结果表明，该体系可将油湿表面反转为水湿表面，33 h后模拟地层水与岩心表面的接触角从130°降至60°。NaCl加量为5000～20000 mg/L时，油水瞬时最低界面张力可达10-2~10-5 mN/m。CaCl2加量为50~200 mg/L时，最低界面张力可达10-3 mN/m数量级，平衡界面张力保持在10-2 mN/m数量级。该体系适用于Na+加量5000～20000 mg/L、Ca2+加量小于200 mg/L，温度为40~70℃的油藏。岩心驱替实验结果表明，注入降压增注体系后，水驱压力降低20%，降压效果明显。

A preferably kind of chemical decompression and augmented injection system was studied under the temperature of 50 centigrade in this paper. The basic recipe was obtained as follows: 0.05% dimeric surfactant HA-1, 0.1% ethanol amine MEA and 0.1% methanol, which could decline instantaneous minimum interfacial tension (IFTmin) between oil and water to 3.78×10-5 mN/m. The system’s performance on changing wettability, resistance to inorganic salts and temperature was investigated. The results showed that the system could convert the oil-wet surface to wet surface observably, and the contact angle between simulated formation water and core decreased from 130° to 60° after 33 hrs. When the dosage of NaCl was 5000—20000 mg/L, IFTmin could reach 10-2—10-5mN/m. While when 50—200 mg/L CaCl2 was added, IFTmin and equilibrium interfacial tension would reach 10-3 and 10-2 mN/m orders of magnitude, respectively. The system was suitable for the reservoir with the conditions of 5000—20000 mg/L NaCl, less than 200 mg/L CaCl2, and 40~70℃. The core displacement experiment results showed that the depressurization rate of the system could reach to 20%, and the system had a good decompression and augmented injection effect for low permeability reservoir.