Corrosion rate prediction of oil flowing in pipe lines by using computational fluid dynamics

Abstract

The transportation of crude oil by pipelines has been reported as the most important process in petroleum industry. The pipe line corrosion problem is a very complex phenomena arising from the concurrent activation of several chemical reactions, one of the most popular instant of corrosion in the two phase flow oil water containing CO2 dissolved in water in pipe lines. The pipe line internal corrosion is under a synergistic effect o f electrochemical reactions, mass transfer and wall shear stress exerted by fluid flow and the effect o f flow velocity. In this work, computational fluid dynamics (CFD) simulations were performed to determine wall shear stress in oil-water two phase fluid flow in pipelines for two types of crude oils (different viscosities) at flow velocities of 0.2, 0.3, 0.5 and 1 m/s. The CFD based empirical model is able to predict corrosion rate of pipelines, with the modelling results validated by actual measurements. The input parameters to ANSYS Fluent are (viscosity, density and fluid flowing velocity), and the output of computer simulation is the wall shear stress. From the computer simulation results, the maximum value of wall shear stress occurs at the maximum value of velocity. From that the corrosion rate in the pipeline was determined by applying the corrosion rate equation at two different values of CO2 partial pressure. From the results, the wall shear stresses for the two crude oils were in different values depending on the properties of the crude. The result showed that corrosion rates for both crudes increased with increase in flow velocity and CO2 partial pressure. This study concluded that the ANSYS capability to predict the corrosion rate of the pipeline for two types of crude oil after determining the wall shear stress with different values of velocities.