Flow corrosion simulation study of local defects in CO2 saturated solution

The inner walls of oil and gas transportation pipelines are prone to the formation of localized pitting defects due to the presence of solid particles in multiphase flow. The continuous flow poses a risk of perforation leakage in the pipe wall. To investigate the development of defects under flow corrosion and assess the impact of flow, a multi-field coupling finite element model incorporating fluid dynamics, reactions, and mass transfer was developed. The flow corrosion of local defects with various depths in a CO₂-saturated solution was simulated. The calculation of mass transfer in corrosion is coupled with the precise flow field solved by large eddy simulation (LES) method. It has been observed that the distribution of corrosive substances is significantly affected by the flow due to local defects. Within these defects, the maximum concentration of corrosion product Fe²⁺ is observed on the upstream surface of defects. While the H⁺ accumulates at the downstream wall, which affects the corrosion rate. The local turbulent state is influenced by the depth of defects, and the interplay of the turbulence intensity with reflux velocity determines the mass transfer.