CFD Simulation of Factors Affecting Gas Hydrate Particle Deposition in Gas Wells

Abstract

Abstract Hydrate deposition has significantly reduced production and generated associated financial losses. Gas hydrate wellbore deposition research mostly considers the cohesiveness of hydrate particles and their adhesion to pipe walls, but the virtual mass force, pressure gradient force, and other forces between particles are not taken into account. This study improves the hydrate particle deposition model by taking into consideration the uneven distribution of hydrate particles in the wellbore caused by gravity. The momentum equation of the hydrate aggregate incorporates the pressure gradient force and virtual mass force. To predict the amount of hydrate deposition on the production tubing, the natural gas-water flow is simulated using an Eulerian-Lagrangian framework and the shear stress turbulence model. Lastly, a sensitivity analysis is executed to scrutinize the impact of a multitude of factors on the deposition quantity of hydrate aggregates on the production tubing. These factors encompass the Saffman lift force, virtual mass force, pressure gradient force, random collision, aggregation, fragmentation, and wall roughness. The simulation results emphasize the significant role of the Saffman lift force in the deposition of hydrate particles. Neglecting this force leads to a substantial deviation from the actual results. As the particle flow rate and wall roughness increase, there is a marked increase in the amount of hydrate particle deposition. Conversely, an increase in particle density results in a decrease in the amount of particle deposition. Specifically, when the particle flow rate escalates from 2m/s to 4m/s, the average deposition amount surges by 81.9%. An increase in wall roughness from 0.1mm to 0.5mm results in a 15.8% increase in the average deposition amount. When the particle injection amount rises from 5e-7kg/s to 5e-5kg/s, the average deposition volume amplifies by a factor of 98. However, when the particle density increases from 900kg/m3 to 2000kg/m3, the average deposition volume diminishes by nearly 32%. These findings provide valuable insights into the dynamics of hydrate deposition. The results of this study will improve current understanding of the regulations governing hydrate deposition in gas wells and contribute to the safety of wellbore flow. They also have significant implications for the prevention and management of gas hydrate wellbore.