黏弹性表面活性剂的流变性质

Rheology of Surfactant Used in Viscoelastic Fracturing Fluids

合成出一种新型的16-4-16,2Br^-型双季铵盐黏弹性表面活性剂,考察了其形成胶束凝胶的能力,测定了体积分数为2%的Gemini16分别与NaSal、NH4Cl水溶液形成胶束凝胶的黏度随剪切力、温度、溶液环境的变化,还考察了Gemini16/NaSal、Gemini16/NH4Cl复配体系的流变性质。结果发现该表面活性剂体系的黏度随其浓度的增大而显著增大;使用最高温度则随着平衡反离子浓度的增大而升高;在较高温度下（40℃）胶束成胶快,且黏度稳定,4%的体系胶束黏度随温度升高有下降趋势,但50-80℃时下降幅度小,在80℃以上急剧降低;体系的表观黏度随pH值的增大而增大,pH值小于6时不增黏,pH值在6-8时迅速增黏,pH值在8-14时,增黏减缓;Gemini/NaSal的弹性模量占优势,趋向于弹性凝胶体;而Gemini/NH4Cl的弹性模量和黏性模量相差不大,弹性不占绝对优势。Gemini16/NaSal复配体系有更高的适用温度,并且有相对更高的黏度值。

A new 16-4-16,2Br-quaternary ammonium surfactant was synthesized in laboratory.The capacity of this surfactant to generate micelle was studied.The change of the viscosities of micellar gels generated with a 2%(V/V) Gemini16 and NaSal and NH4Cl,with the variation of shear strength, temperature,and the environment was investigated.Also investigated was the rheology of the complex Gemini 16/NaSal and Gemini16/NH4Cl systems.It is found that the viscosity of the surfactant compound system increases with the increase in the concentration of the surfactant.The temperature stability increases with the increase in the concentration of the counter ions.Micelles are generated faster at higher temperatures(say,40 ℃),and the viscosity of the system is comparatively stable.A 4% surfactant system has a mcellar viscosity that decreases with temperature,and a small decreasing magnitude is found at temperature between 50 and 80 ℃,and the viscosity decreases dramatically above 80 ℃.The apparent viscosity of the system increases with pH elevating and at pH less than 6 no apparent viscosity increase can be found.Apparent viscosity increases very fast at pH between 6 and 8 and at pH between 8 and 14 the increase of the apparent viscosity becomes slowly.Gemini/NaSal system has a greater elastic modulus and tends to be a elastic gel,while the Gemini/NH4Cl system has elastic modulus and viscous modulus that are almost the same.An organic counter ion compound system has higher temperature stability and higher viscosity.