Fluid structure governing the corrosion behavior of mild steel in oil–water mixtures

Abstract

Corrosion was correlated with fluid-structure based on a comparative investigation of the corroded surface morphology of mild steel and the microscopic feature of oil–water mixture. It was found that the corrosion rate increased with increasing water cut and flow rate, while the corrosion morphology closely relied on the mixing state of oil and water. In high-pressure CO₂ saturated water-in-oil emulsions, the corrosion product particles grew gradually with enlarging water droplets at a low flow rate, but at a high flow rate an abrupt propagation of corrosion damage occurred when the water droplets were larger than a critical size, which could be attributed to the changed fluid behavior of water droplets near the steel surface. It provides a deep insight into the corrosion phenomena at the steel/fluid interface, which is helpful for the risk evaluation of aggressive multiphase fluids.