Main control factors and prediction model of flow-accelerated CO2/H2S synergistic corrosion for X65 steel

Abstract

As an important infrastructure for offshore petroleum development, submarine pipelines are the lifeline of offshore petroleum resources development. However, the medium flow containing H2S and CO2 threatens the normal production of oil fields. Based on 18 groups of orthogonal experiments, considering CO2 partial pressure, H2S partial pressure, temperature, pH, chloride concentration and liquid flow rate, the general and local corrosion rate were obtained. The corrosion products were characterized with SEM/EDS and XRD. The main controlling factors and corrosion mechanism were explored. Under the experimental conditions, CO2 and H2S were the main controlling factors of general and local corrosion. With the increase of gas partial pressure, the corrosion rate increaseed gradually. Flow accelerated the synergistic corrosion mechanism and model were established. Within the working condition range, the prediction error was less than 20%, which was better than ECE prediction model. The results can improve the integrity management of submarine pipelines.