Sand Transport and Deposition Behaviour in Subsea Pipelines for Flow Assurance

Sand transport through tubing and pipeline could cause a series of problems to flow assurance, if not properly managed or controlled. The most serious problem is the accumulation and erosion in multiphase flow pipelines and the surface equipment. Therefore, the importance of understanding the transport and deposition behaviour of sands through multiphase flow pipelines cannot be overemphasized. This study presents the sand transport and deposition characteristics in the complicated multiphase flow pipeline. The numerical result shows that the slurry velocity presents a uniform distribution in the multiphase flow pipeline at the sand concentration of 5% and the sand diameter of 50 µm. However, the slurry velocity at the bottom of the pipeline is significantly smaller than that at the top when the sand concentration and diameter reach 30% and 300 µm, respectively. It indicates that the sand deposition at the bottom of the pipe declines the slurry velocity and transport capacity. The deposition thickness is approximately 10% of the pipe diameter even at the low concentration of 5% sand with a small sand diameter of 50 µm and a high slurry velocity of 1.8 m/s. The sand deposition reaches about 30% of the pipe diameter at the same low concentration and high slurry velocity when the sand diameter increases to 300 μm.