Influence of Nanoparticles and Surfactants on Stability and Rheological Behavior of Polymeric Nanofluids and the Potential Applications in Fracturing Fluids

Water-based fracturing fluids are widely used in hydraulic fracturing to stimulate reservoirs. However, a novel fracturing fluid system needs to be developed for use in complex and challenging environments due to the high temperature and pressure reservoir conditions. In this study, the polymeric nanofluid hydrolyzed polyacrylamide (HPAM)/sodium dodecyl sulfate (SDS)/nanoparticles (NPs) was prepared with a polymer acrylamide (AM)-sodium acrylate (SA)-octadecyl dimethyl allyl ammonium chloride (C18DMAAC) and amino modified multiwall carbon nanotubes (CNT-NH2) by hybrid nanotechnology. It was found that this polymeric nanofluid improved the viscosity of the basic polymer solution and still exhibited excellent stability at 90 °C, and the surfactant played an important role in the dispersion of nanoparticles in polymer solution. The rheological studies showed that the synergistic effect of surfactants and nanoparticles improved the viscoelasticity and temperature and shear resistance of the polymeric nanofluids, which showed an increased modulus at 1.0 Pa, and the shear viscosity remained above 70 mPa s at 90 °C. In addition, the addition of nanoparticles altered the wettability of the reservoir rock, thus changing the distribution and flow of fluid in the reservoir. The drag reduction rate of this polymeric nanofluid was up to 60.7%, and the fluid loss coefficient decreased to 1.46 × 10–5 m/min1/2. Therefore, the polymeric nanofluids composed of surfactants, nanoparticles, and polymers hold potential applications in the oilfields to improve the hydraulic performance of fracturing operations.