强化润湿表面活性剂复配体系构筑与性能评价

Construction and performance evaluation of compound surfactant system with wettability control

关键词:  助表面活性剂  润湿调控  界面张力  油膜剥离  提高采收率

Key words:  cosurfactant  wetting control  interfacial tension  oil film peeling  enhanced oil recovery

摘要:

目的 阴离子?非离子型表面活性剂具有改变岩石表面润湿性的能力，然而其降低油水界面张力能力有限。因此，对其复配一种助表面活性剂以实现油水与油固界面协同调控，旨在解决残余油开发困难的问题。方法 通过Williamson成醚反应，在非离子表面活性剂月桂酸二乙醇酰胺分子中引入磺酸根基团，合成强润湿调控主表面活性剂——月桂酸乙醇酰胺磺酸钠（HLDEA）。以降低油水界面张力为指标，复配表面活性剂壬基酚聚氧乙烯醚硫酸钠（NPES），得到最佳强化润湿高效驱油体系。对其降低油水界面张力性能、润湿调控性能、油膜剥离性能及驱油性能进行评价。结果 质量分数为0.3%的HLDEA+NPES体系可将油水界面张力降低至3.8×10^-3 mN/m，达到超低界面张力。此外，HLDEA+NPES分子可吸附至亲油岩石表面，将亲油岩心表面水下油滴接触角由41.34°增至162.53°，将疏水岩石表面调控为水下强疏油状态。75 ℃下，经HLDEA+NPES体系处理24 h，载玻片表面油膜面积减少75.3%，实现油膜整体剥离。结论 室内岩心动态驱油实验结果表明，HLDEA+NPES体系可将采收率提高至63.60%，在水驱基础上提高了28.74个百分点，在超低界面张力体系驱基础上提高了7.80个百分点。HLDEA+NPES体系可同时达到超低界面张力和调控岩石表面润湿性，具有应用潜力。

Abstract:

Objective Anionic-nonionic surfactants have the ability to change the wettability of rock surface, but their ability to reduce oil-water interfacial tension is limited. Therefore, a cosurfactant is compounded to achieve synergistic regulation of oil-water and oil-solid interface, aiming to solve the difficulty of residual oil development. Method Through the Williamson etherification reaction, a sulfonic acid group was introduced into the nonionic surfactant lauric acid diethanolamide to synthesize an enhanced wetting-regulated cosurfactant—lauric acid ethanolamide sulfonate (HLDEA). With the reduction of oil-water interfacial tension as the index, the surfactant nonylphenol polyoxyethylene ether sodium sulfate (NPES) was compounded to obtain the best enhanced wetting high-efficiency oil displacement system. The oil-water interfacial tension reduction performance, wetting control performance, oil film peeling performance and oil displacement performance were evaluated. Result The 0.3 wt% HLDEA+NPES system could reduce the oil-water interfacial tension to 3.8×10^-3 mN/m, which achieved ultra-low interfacial tension. Meanwhile, HLDEA and NPES molecules could be adsorbed to the surface of lipophilic rock, and the underwater oil contact angle increased from 41.34° to 162.53°, which regulated the surface of hydrophobic rock to a strong underwater oleophobic state. At 75 ℃, the oil film area on the surface of the slide was reduced by 75.3% after HLDEA+NPES system treatment for 24 h, and the overall peeling of the oil film was realized. Conclusion The results of indoor core dynamic oil displacement experiments showed that HLDEA+NPES system could increase the recovery rate to 63.60%, which increase by 28.74 percentage points on the basis of water flooding and 7.80 percentage points on the basis of ultra-low interfacial tension system flooding. The HLDEA+NPES system can simultaneously achieve ultra-low interfacial tension and wetting control of rock surfaces, which has practical application potential.