基于假四子表面活性剂的pH响应型清洁压裂液的研制与性能评价

Preparation and Performance Evaluation of pH-responsive Clean Fracturing Fluid Based on Pseudo-tetrameric Surfactants

尹太恒 问晓勇 杜现飞 王成旺 闫朝雯 杨子浩

YIN Taiheng WEN Xiaoyong DU Xianfei WANG Chengwang YAN Zhaowen YANG Zihao

黏弹性表面活性剂压裂液又被称为清洁压裂液，由于其破胶完全、无残渣、地层伤害小等优点，已在水力压 裂领域受到广泛关注。但合成工艺复杂、成本高以及无法重复利用等问题限制了清洁压裂液的实际应用。基于 油酸酰胺丙基二甲基叔胺与丁烷四羧酸在特定pH条件下相互作用形成“假”四子表面活性剂，进而自组装形成 蠕虫状胶束的特性，构建了表观相态和流变学行为受pH调控的pH响应型清洁压裂液，系统研究了这种清洁压 裂液的pH响应行为，包括表观相态、黏度、流变学行为、pH响应循环性以及微观结构等，并评价了其耐温耐剪切 以及破胶性能。研究结果表明，通过调节pH，压裂液的零剪切黏度可达240 Pa·s 以上，并能够在高黏凝胶状态与 低黏水溶液状态间循环切换4 次以上。所构建的清洁压裂液在90 ℃、170 s-1条件下剪切60 min 后，黏度仍保持 在200 mPa·s 以上，具有良好的耐剪切性能。此外，该压裂液可在1 h 内实现完全破胶，且破胶液黏度低、无残渣。

Viscoelastic surfactant fracturing fluids，also known as clean fracturing fluids，have attracted extensive attention in the field of hydraulic fracturing because of their advantages such as complete gel breaking，no residues and low formation damage. However，the complex synthesis process，high cost and the inability to reuse have limited the practical application of clean fracturing fluids. In this paper，a pH-responsive clean fracturing fluid with pH-regulated apparent phase and rheological behaviors was constructed based on the mechanism of pseudo-tetrameric surfactant and wormlike micelles formed under specific pH conditions by N，N-dimethyl oleoaminde-propylamine and 1，2，3，4-butanetetracarboxylic acid. Then，the pH-responsive behaviors of the clean fracturing fluid，including apparent phase state，viscosity，rheological behavior，pH-responsive cyclicity and microstructure were systematically studied. Finally，the temperature and shear resistance，and gel-breaking performance were evaluated and analyzed. The results showed that the zero-shear viscosity of the fracturing fluid could reach more than 240 Pa·s，and it could switch between high-viscosity gel state and low-viscosity aqueous solution state more than four times by adjusting the pH value. The viscosity of the constructed clean fracturing fluid was still higher than 200 mPa·s after shearing at 90 ℃ and 170 s-1 for 60 min，indicating that it had good shear resistance. In addition，the fracturing fluid could be completely broken within one hour， and the gel broken fluid had low viscosity and no residues.

10.19346/j.cnki.1000-4092.2023.02.009