Water flushing in the oil sand slurry hydrotransport pipeline: parametric insights from integrated in-situ measurement and CFD modelling

• An industrial scale CFD model is developed for a water flushing of hydrotransport pipeline. • The 3D model is validated with seven different set of in-situ measurements for single and multisolid in the system. • Effect of water flow velocity, PSDs and pipe geometry on water flushing has been investigated. • An optimized operating condition for hydrotransport pipeline flushing system is provided through the CFD simulations. The deposition of solid particles is a critical challenge in long-distance pipeline transportation within the oil and gas industry, as it can cause severe flow restrictions and eventual system failure. To address this, the present study investigates the water flushing process as a mitigation strategy through a combination of field measurements and computational fluid dynamics (CFD) simulations. An unsteady Eulerian mixture multiphase model incorporating the kinetic theory of granular flow (KTGF) is developed to capture the solid–liquid interactions during flushing. The model is validated against site data, showing good agreement with an uncertainty of less than ± 20%.The study systematically examines the effects of flow velocity, particle size distribution (PSD), and pipeline geometry on solid removal efficiency and water consumption. Simulations are conducted for velocities ranging from 3-6 m/s, four PSDs with particle sizes between 75-355 μ m, and pipe diameters of 24-29 inches. Results indicate that an optimal combination of 4 m/s flow velocity, a PSD enriched with coarser particles (PSD2), and a larger 29-inch pipe yields the most effective flushing performance under the considered operating conditions. Flow visualization provides detailed insights into particle mobilization and transition mechanisms across regimes. Furthermore, a mathematical correlation between water consumption (WC) and solid removal efficiency (R) is established, enabling quantitative assessment of the trade-off between resource use and cleaning effectiveness. The findings offer a validated CFD framework and practical guidelines for optimizing water flushing operations, ensuring stable slurry transport and extending pipeline service life in industrial applications.