可重复利用NaOA/Na_3PO_4黏弹性胶束压裂液微观结构与流变特性研究

采用电解质Na3PO4溶液诱导阴离子表面活性剂油酸钠(Na OA)形成蠕虫状胶束体系。利用冷冻断裂蚀刻透射电子显微镜技术(FF-TEM)和流变学方法,研究了Na3PO4在不同质量分数条件下诱导Na OA形成胶束体系的微观结构、流变特性、破胶行为以及重复利用等性能。通过对体系动态模量、剪切黏度、复合黏度等物理量的测量分析,发现该胶束体系在较宽的频率范围内呈现蠕虫状网状结构和优良的黏弹性能。通过内相破胶剂研究了该体系的破胶行为,并结合流变特性测试,证实了该胶束体系具有重复利用的可行性。与目前已成熟应用的羟丙基瓜胶(HPG)压裂液冻胶及其破胶液微观FF-TEM对比分析显示,Na OA/Na3PO4黏弹性胶束体系具有清晰的网状结构,在温和条件下能够实现和HPG经强氧化破胶后相当的破胶效果。上述结果表明Na OA/Na3PO4黏弹性胶束体系能够作为可重复利用清洁压裂液体系,应用前景广阔。

Research on microstructure and rheological properties of recyclable NaOA/Na3PO4 viscoelastic micelle fracturing fluid

The electrolyte Na3PO4 solution is used to induce anionic surfactant NaOA to form wormlike micelle system. By using freeze-fracture transmission electron microscopy (FF-TEM) technology and rheology method, the research about Na3PO4 which induces NaOA to form micelle system under different mass fractions， was conducted on the functions like microstructure, rheological properties, gel breaking behavior and recycling. By measuring and analysis of physical quantities about dynamic modulus, shear viscosity, compound viscosity, etc. of the system, it was found that this micelle system shows wormlike net structure and good viscoelastic performance in a broad frequency. Using gel breakers, the gel breaking behavior of the system was studied, and combined with the test on rheological properties, it is proved that this micelle system is good for repeated use. Through comparison with the now maturely used hydroxypropyl guanidine gum (HPG) fracturing fluid and microcosmic FF-TEM of its breaking fluid, it shows that the NaOA/Na3PO4 viscoelastic micelle system has clear net structure and can achieve the breaking effectiveness equal to HPG after breaking by strong oxidant under moderate conditions. The above results show that the NaOA/Na3PO4 viscoelastic micelle system can be used as recyclable clean fracturing fluid system and has a broad application prospect.