(17d) Detailed Flow Modeling of Erosion in Subsea Equipment

Particulate erosion is one of the common flow assurance problems in subsea and other upstream equipment. Erosion causes failure of equipment and is a safety hazard. A good understanding of the causes of erosion is essential before ways of mitigating them may be designed and verified. Erosion is caused by the interaction of fluid and particle flow with the walls of the equipment. The fundamental basis of erosion is the fluid mechanics of particulate flow in a fluid medium. Computational fluid dynamics has proven to be useful in understanding this multiphase flow and erosion. In this paper we demonstrate the importance of using appropriate boundary treatment for particle interactions with walls for a realistic prediction of particulate erosion.

Inclusion of microscopic surface roughness of walls affects post collision rebound of the particles and then it has an important influence on the areas of the equipment prone to erosion. While validating simulation results with experiments done by Mason et. al. it was found that ignoring surface roughness, incorrectly predicts the amount and extent of erosion. The other effect that is important to include is the change in the fluid domain due to equipment material removed by erosion. Change in fluid domain changes the particle fluid dynamics and thus impacts the new areas of equipment where erosion might start.

We present a CFD implementation of the above said effects in ANSYS CFX and ANSYS Fluent and its validation with the experimental data of Mason et. al. We then showcase the effects of this implementation on typical equipment found in subsea fields