Double-Network Structure Slickwater Reinforced by Silane-Modified Nanofibers: Enhancing the Sand-Carrying Performance

Slickwater fracturing fluid has gained wide attention in hydraulic fracturing due to its advantages, such as low pipeline friction and minimal formation damage. However, its low viscosity leads to poor sand-carrying performance, affecting the effectiveness of fracturing operations. There is an urgent need to develop a new slickwater system with an excellent sand-carrying performance. In this study, cellulose nanofibrils (CNFs) were modified via alkylation to prepare silane-modified nanofibers (denoted as S-CNFs). The successful preparation of S-CNFs was confirmed by Fourier transform infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The research results indicate that S-CNFs have an excellent dispersion stability. S-CNFs were then introduced into the conventional slickwater to develop the S-CNFs-reinforced slickwater, which meets industry standards in terms of drag reduction and core damage evaluation. Through rheological tests, the S-CNFs-reinforced slickwater shows excellent strength and temperature shear resistance. Additionally, the system also shows the wider elasticity-dominated range in the viscoelasticity test, confirming the improvement in proppant-carrying capacity. Compared with the conventional slickwater, the S-CNFs-reinforced slickwater transports proppants deeper into fractures in the dynamic proppant-carrying experiment. It reduces the area of sand banks in simulated fractures by 16.4% and the residual sand amount by 14.8%. Scanning electron microscopy (SEM) was employed to observe the formation of the double-network structure constructed by polymers and S-CNFs in the S-CNFs-reinforced slickwater. This double-network structure confirms the intrinsic mechanism of the enhanced sand-carrying performance. These findings exhibit that S-CNFs can significantly improve rheological properties and sand-carrying capacity, providing a theoretical foundation for the further development of modified nanofiber-based slickwater fracturing fluids.