A Quantitative Framework for Wall Deposition of Hydrate Particles in Water-Dominant Flow

Understanding the mechanism of hydrate blockage formation in water-dominant flow is increasingly important due to growing interest in natural gas hydrate production, refrigerant applications, and carbon capture and storage. This study proposes an updated framework to predict the wall deposition of hydrate particles in water-dominant systems alongside the established approach of hydrate deposition from entrained water droplets in the gas phase. The model, developed based on the updated framework, calculates the hydrate deposition rate while considering the particle size distribution, which evaluates the migration velocity (to the wall surface) and adhesion force for each hydrate particle size. Flow simulations of water-dominant flow with the model were conducted, specifically for the water production line of the second offshore methane hydrate production test in Japan in 2017. The simulation results provided reasonable predictions, consistent with the actual production test. The model and simulation results suggested the importance of hydrate adhesive force and water velocity on deposition rate. In the simulations, the hydrate particles could not stick to the pipe wall (unable to adhere) when the water velocity was high enough (greater than 0.7 m/s based on the adhesion force of hydrate particles in water), which resulted in higher drag and lift forces acting on the particle on the wall surface. The lower adhesive force in the water-dominant systems (compared to gas-dominant systems) resulted in much less wall deposition. This work provides new insights into the fundamentals of hydrate deposition in water-dominant systems.