Study On The Mechanism Of Nano Particles And Wormlike Surface Function

The clean fracturing fluid has poor temperature resistance,rapid viscosity reduction at high temperature and large filtration loss.Nanoscale can improve the performance of the fracturing fluid and reduce the filtration of the clean fracturing fluid.However,the nanoparticles are easily aggregated,and it is difficult to perform the properties of nanomaterials.Therefore,it is of great significance to make surface modification of nanoparticles and compound clean fracturing fluid.In this paper the surface of nano SiO₂ was modified by 3-amino-propyl triethoxy silane?KH-550?and the hydrolysis process of KH550 was studied by electrical conductivity method.The modified effect was characterized by infrared spectrum and Zeta potential.The results showed that the best hydrolysis conditions of KH550 were as follows:the water/ethanol mixed solution was used as the solvent and the positive hydrolysis method was used.When the KH550 volume fraction was 10%,the hydrolysis effect of KH550 was the best.The best modification conditions of nano SiO₂ are:the reaction temperature is 70?,the ratio of SiO₂to KH550 is 1:4,the reaction 3H is at 3h,and the surface hydroxyl number is the smallest of2.2/nm².In this paper,the mechanical agitation method and ultrasonic oscillation method were used to disperse the nano particles evenly in the fracturing fluid,and the rheological properties of the viscoelastic surfactants were investigated by the rheology method,and the mechanism of the modified nano SiO₂ on the viscoelastic fluid was discussed.The results showed that 3%N-methyl salamyl sulfonate sodium?JXJ209?formed a high strength micellar network structure in 6%KCl salt water,and the zero shear viscosity could reach 44.06Pa�s.The zero shear viscosity of the composite system can be increased by 12.6 and 3.8 times with the mass fraction of 0.3%KH550-SiO₂ adding a vermicular micelle with a mass fraction of 3%to 4%of KCl.However,when the KCl mass fraction increased to 6%to 7%,the gain effect of nano began to weaken.Under low oscillation frequency,the thickening effect of KH550-SiO₂ on JXJ209/KCl viscoelastic micelles is obvious.Not only the relaxation time is prolonged,but also the viscoelasticity of the system is improved.In addition,KH550-SiO₂ can also improve the thermal stability of JXJ209/KCl wormlike micelles and anti filtration.The viscoelastic fluid with a formula of 3%209+5%KCl+0.3%KH550-SiO₂ is used to evaluate the performance of the fracturing fluid.The viscosity of the nanocomposite viscoelastic fluid remains at 25mPa�s at the shear rate of 170s^-11 and 100?.The viscosity is less than 5mPa�s and the core damage rate is only 8.9%after the gel breaking,and the performance evaluation of the fracturing fluid is excellent.