Development of Numerical Model to Assess Internal CO2 Corrosion of Oil and Gas Pipelines

A comprehensive numerical model, developed for computing the corrosion rates generated by CO₂ saturated aqueous solutions, is used to study top-of-the-line corrosion in wet gas pipelines. The fundamental fluid flow is characterized by numerical solutions to Navier-Stokes conservation equations for mass, momentum and energy, accompanied by models to capture turbulence generated by the flow. The corrosion rates are then computed by modeling the electrochemical processes occurring at the metal substrate such as the cathodic reduction of carbonic acid, hydronium ions and anodic oxidation of the metal component. The developed model is first validated against experimental data for CO₂ saturated single phase aqueous solutions and is later extended to model corrosion behavior in gas dominated multiphase flows across various flow network configurations. Elaborate details of the multiphase flow behavior such as time dependent distribution of liquid/gas phasic fractions are provided. The effects of modulated superficial velocity of gas and liquid components as well as the temperature on the overall corrosion rates are monitored and satisfactory trends against available experimental data is observed.