Static Proppant Settling Velocity Characteristics in High Viscosity Friction Reducers Fluids for Unconfined and Confined Fractures

Measuring proppant settling velocity in high viscosity friction reducers (HVFRs) plays a critical key for evaluating proppant transport in hydraulic fracture treatment. Settling of particles is governed by several factors such as fluid rheology (viscosity and elasticity), proppant size, retardation confining walls effect, and fracture orientation. The objective of this experimental study was to determine how these factors would influence particle settling velocity in hydraulic fracturing applications. The experiments were conducted in unconfined and confined fluid conditions. Fracture cell was designed in certain ways to capture the impact of fracture orientation by 45°, 60°, and 90° on settling velocity. Results showed HVFR provided better proppant transport capability than regular FRs used in slickwater. Proppant settling velocity using HVFR was decreased by 80%. Results obtained from confined fluid experiments showed that proppant settling velocity decreased due to the confining walls exert retardation impact. The wall retardation was also reduced as the fracture width increased. Changing fracture orientation from vertical position (90 degree) to 45 degree led to high reduction in proppant settling velocity.