Flowloop investigation into hydrate formation and slurry flow in the presence of micron-sized sand particles

Abstract

Hydrate flow assurance is critical to the exploitation of natural gas hydrate reservoirs. So far, hydrate formation and slurry flow behaviors in the presence of micron-sized sand particles are still unclear. Therefore, experiments of hydrate formation and slurry flow in the presence of micron-sized sand particles were performed in a high-pressure flow loop. The induction time and formation subcooling during hydrate formation process with micron-sized sand particles were studied, and cumulative formation probability under different formation subcooling with micron-sized sand particles was explored. Coupled with a semi-empirical hydrate formation kinetics model, hydrate formation kinetics parameters with micron-sized sand particles were calculated. The influence mechanism of micron-sized sand particles on hydrate formation was revealed. The calculation method for hydrate slurry viscosity under conditions of constant volume fraction and variable shear rate was derived. Combined with viscosity of hydrate slurry with micron-sized sand particles, the importance of the fractal dimension to the accuracy of slurry viscosity prediction was emphasized. Considering hydraulic factors, collision between hydrates or micron-sized sand particles and pipe wall, and friction between hydrates or micron-sized sand particles and pipe wall, the calculation method of flow resistance coefficient of hydrate slurry with micron-sized sand particles was established.