Rheological Characteristics of Viscoelastic Surfactant Fluid Mixed With Silica Nanoparticles

Since the surfactant can form rod-like micelles or even cross-link structures, viscoelastic surfactant (VES) fluid has unique rheological characteristics. The demerits of VES fluids have been proven after being applied as the fracturing fluid for several years. However, the fluid has high fluid loss and a low viscosity at high temperature, which limits the application to hydraulic fracturing. This paper focuses on the VES fluid mixed with nanoparticles which should be an effective way to maintain the viscosity at high temperature and high shear rate. The experiments were based on preparation of uniform and stable nanocolloids, which utilize Microfluidizer high shear fluid processor. Dynamic light scattering and microscopic methods are employed to investigate the stability and micro-structure of the VES fluid. The effects of temperature, shear rate and volume fraction of the nanoparticles on rheology of VES were studied. The SiO₂ nanoparticles could significantly improve the rheological performance of VES fluid, although the rheological performance at the temperature over 90 °C needs to be enhanced. The mechanisms of interactions between nanoparticles and micelles are also discussed later in the paper. At the end, the potential of VES fluid mixed with nanoparticles during application in fracturing process was discussed.