Particle clustering dynamics in dense-phase particle-fluid slurries

This study investigates clustering mechanisms during flow and transport of dense-phase particle–fluid slurry, evaluating the slurry’s complex internal composition effects on particle conveyance. Dense-phase particle–fluid flow and transport are affected by frequent particle–particle collisions, leading to development of particle clusters. Particle conveyance and irregularities of particle placement in fractures due to clustering influence is a topic of interest for proppant injection used during hydraulic fracturing for enhancement of geothermal and hydrocarbon reservoirs. A micromechanical (particle-level) approach using the Discrete Element Method coupled with computational fluid mechanics (DEM-CFD) reveals interesting underlying mechanisms which govern overall slurry conveyance. In this study, qualitative clustering shapes and quantitative clustering characteristics are related to variances in the Durand-Froude number and injected particle volumetric concentrations. Furthermore, this study compares coupled DEM-CFD model results with simplified particle transport evaluations used in some hydraulic fracture simulation software. Results show that particle deposition dynamics do not fully follow predictions based on simplified evaluations at higher injection volumetric concentrations. In most of these cases, conveying particle suspension concentration is non-linear in behavior that differs from the anticipated particle behavior described by simplified evaluations. Overall, this work improves understanding of flowing particle slurry structure and slurry clustering influence on flow and transport.