Modeling agglomeration and deposition kinetics of hydrate particles under horizontal multiphase flow conditions

Abstract

Natural gas hydrate is considered a critical energy source for the future due to its vast global reserves. To explore the impacts of hydrate particle growth, agglomeration and sedimentation on the flow assurance of oil and gas transportation pipelines during hydrate extraction, this study employs Computational Fluid Dynamics (CFD) and extended discrete element method (EDEM) to develop a three-dimensional model under horizontal multiphase flow conditions. The model simulates hydrate particle growth and distribution, as well as their adhesion and deposition on the pipe wall under varying particle volume fractions within the pipeline. Furthermore, it examines the effects of particle diameter and various fluid compositions (oil, water, and gas) in horizontal pipelines on hydrate slurry flow characteristics. Results indicate that hydrate layer formation begins at a particle volume fraction of 20 %. When the volume fraction reaches to 30 %, the frequency of particle-wall collisions and pressure drop increase significantly. Deposition prevention during this critical phase enhances pipeline flow assurance. Variations in pressure drop correlate with particle mass fractions; agglomeration-induced volume expansion gradually shifts the dominant forces from adhesion and friction to inertia, thereby reducing the propensity for wall adhesion. In gas-dominated systems, transition zones exist within the velocity range of 0.28 to 0.42 m/s, where particle population stabilize at (2.99 ± 0.16) % under dynamic equilibrium conditions. These preliminary findings offer theoretical support for analyzing the challenges associated with hydrate particle agglomeration and deposition in oil and gas pipelines.