Development and Performance Evaluation of a Novel Silica Nanoparticle-Reinforced CO2-Sensitive Fracturing Fluid with High Temperature and Shear Resistance Ability

In order to further increase the temperature and shear resistance of a conventional CO2-sensitive clean fracturing fluid, a novel silica nanoparticle-reinforced CO2-sensitive fracturing fluid system was developed. The system was prepared with the compositions of 2.0 wt % N-[3-(dimethylamino) propyl] oleamide, 1.5 wt % sodium p-toluene sulfonate (NaPts), and 0.025 wt % silica nanoparticles. The rheological properties, temperature resistance, shear resistance, sand-carrying capacity, gel-breaking property, and core damage property of the system were systematically studied and evaluated. Compared with the conventional CO2-sensitive fracturing fluid system, the silica nanoparticle-reinforced CO2-sensitive fracturing fluid system has a better viscosity increase effect, and the zero-shear viscosity increases from 2900 to 3500 mPa·s. By adding and removing CO2, the viscosity of the system can be repeatedly converted from high to low, and the reusable property can be realized. After introducing silica nanoparticles, the temperature resistance ability of the clean fracturing fluid increases from 100 to 130 °C, the sand-carrying effect increases by 23%, rapid and thorough gel breaking occurs, and core damage is less than 13%. We expect that this study can broaden the application of the CO2-sensitive clean fracturing fluid in low permeability, high-temperature reservoirs and provide a theoretical basis for field applications.