Formation of gas hydrates in systems with high water content is one of the major challenges facing the petroleum industry today. Conventional mitigation using thermodynamic inhibitors is expensive due to large water volumes, while the most recent flow management strategies (anti-agglomerants, cold flow, etc.) have not yet been adopted because the dynamics of hydrate slurry are insufficiently understood. The present contribution examines a flow of gas, hydrates and water using computational fluid dynamics (CFD). The model couples the effective viscosity of gas-water slurry with the average size of hydrate agglomerates and the adhesive force that binds them. The model was validated against experimental pressure drop, demonstrating tolerable discrepancies. According to the simulations, onset of hydrate plugging is most probably related to the formation of a viscous bed at the gas-slurry interphase at hydrate concentrations slightly above 15%. A simplified theoretical approach is proposed for engineering estimates of pressure drop in the hydrate slurry pipes. (C) 2018 Elsevier Ltd. All rights reserved.