Numerical Simulation Study on Sedimentary Characteristics of Nondiagenetic Hydrates.

Abstract

This study investigates the effects of flow velocity, hydrate volume fraction, and sand content on the deposition characteristics of noncementing hydrate particles in pipelines using ANSYS Fluent. Simulations analyzed key locations within the pipeline to reveal the influence of flow parameters and fluid composition on hydrate deposition behavior. Results demonstrate that flow velocity significantly impacts hydrate deposition: at low flow velocities, particles tend to form thick deposition layers on the pipe wall; as the velocity increases, fluid shear forces suppress deposition; however, at high flow velocities, intense momentum fluctuations lead to particle redeposition in pipe bends and constricted areas. An increase in hydrate volume fraction markedly enhances deposition, especially in low-flow regions and areas with geometric changes in the pipeline. The presence of sand particles alters the fluid flow characteristics, locally increasing fluid momentum, which can inhibit hydrate deposition under certain conditions. Additionally, higher sand content significantly reduces pipeline pressure drop, with a 5% increase in sand content lowering pressure drop by approximately 3-5%. In bends, the average hydrate particle diameter is 10-15% larger than in straight sections, and the increased localized deposition significantly raises resistance, making bends high-risk areas for hydrate accumulation. Simulation results align well with experimental findings. This study provides numerical insights into the deposition mechanisms of noncementing hydrates in pipelines and offers theoretical support for pipeline design and operational optimization.