Numerical simulation of viscoelastic slickwater jets in hydraulic fractures

Large-scale slickwater fracturing is a key technique for unconventional reservoir stimulation, where the flow behavior of viscoelastic slickwater fracturing fluid within fractures critically impacts both fracture propagation and proppant transport. However, conventional models struggle to characterize the polymer stress characteristics of viscoelastic fluids. This study employs the finitely extensible nonlinear elastic with Peterlin closure, which accounts for the nonlinear finite extensibility of polymer molecules, and introduces a Laplacian term to ensure numerical stability, establishing a fracture geometry model with main and branch fractures. Simulations investigate the flow characteristics of viscoelastic fluids under perforation injection conditions at different velocities and Weissenberg numbers, as well as changes in the flow field within main and branch fractures. The analysis reveals significant turbulent drag reduction due to polymer stress, where elastic stretching enhances flow stability through elastic energy storage. When velocity exceeds the elastic suppression threshold (under the numerical simulation conditions in this study, the fluid velocity threshold is 4.5 m/s, which corresponds to a flow rate of approximately 7 l/min per hole), the fluid transitions to a turbulent regime, hindering fluid entry into branch fractures and resulting in a characteristic trend of initial increase followed by decrease in branch fracture flow division. These findings provide theoretical support for selecting slickwater properties during proppant transport operations.