The Thickening Mechanism Of Temperature-Resistant Anionic Gemini Surfactant Cleaning Fracturing Fluid

With the continuous development of low permeability oil and gas reservoirs,the performance requirements of fracturing fluid are also getting higher and higher.In recent years,the developed fracturing fluid has solved the traditional fracturing fluid,,The residue of the shortcomings.Clean the fracturing fluid thickener mainly for specific surfactants,surfactant thickening effect directly affect the performance of clean fracturing fluid.The anionic gemini surfactants have lower critical micelle concentration and loss of formation rock adsorption;and the water solubility is good,and the permeability of the formation is basically harmless;it can form a micrometer structure with little curvature at low concentration,Obviously,the potential for reducing the amount and cost of cleaning the fracturing fluid is huge.At present,the research on clean fracturing fluid at home and abroad is mainly aimed at the experimental study on the preparation of viscoelasticity,damage,rheology,friction resistance and high precision of fracturing fluid.The mechanism of the viscosity of surfactants is better at the initial stage.The mechanism of temperature,concentration,additives and the viscosity of nano-particles surfactant solution is rarely reported.Therefore,it is of great significance to study the thickening mechanism of temperature-resistant anionic gemini surfactant cleaning fracturing fluid.In this paper,the relationship between the temperature resistance,the molecular structure and the solution viscosity of the anionic gemini surfactants were investigated by reference to SY/T5107-2005.The effects of concentration,additives and nanoparticles on DS10-2-10 and DS18-3-18 solution viscosity.The micelles of self-assembled micelles of different molecular structures of anionic gemini surfactants were characterized.The micelles of DS10-2-10 and DS18-3-18 solutions were characterized by different concentrations,additives and nanoparticles.The The results showed that the sensitivity of DS10-2-10 was the best,DS18-3-18 was the same,DS10-3-10 and DS18-3-18 were the best Self-assembly to form sheet micelles,indicating that the sheet micelle has a strong temperature resistance.According to the order of the thickening effect of the solution,the micelles formed by the self-assembly of the surfactant in the solution were worm-like,flaky,rod-like,spherical and lamellar.The more the number of worm-like micelles,The larger the density of the spherical micelles contributes to the viscosity of the solution is larger than that of the smaller spherical micelles.DS10-2-10 in the concentration of 0.2-2.5% change process,the solution formed by the self-assembly of the micelles through the rod-like to the process of change,and the sheet micelle size gradually increased,DS10-2-10 solution The concentration of DS18-3-18 in the process of DS18-3-18 was 0.05%,0.1%,0.2%,1% and 2%,and the agglomerated state of DS18-3-18 molecules in solution was subjected to flaky micelles.The results show that the DS18-3-18 is self-assembled in solution after adding 4% DS18-3-18 NaCl,sodium benzoate,dodecyl alcohol and sodium dodecylbenzene sulfonate.Into the sheet of micelles change,the solution viscosity also changes accordingly.After adding 0.3% nano-SiO2,the agglomeration of nano-SiO2 occurs in the solution,and many of the SiO2 are clustered together and attached to the sheet micelles formed by DS18-3-18 self-assembly,which hinders the relaxation of the lamellar micelles,Macroscopically showed a significant reduction in solution viscosity.