Corrosion Behavior of P110 Steel in Vapor-Liquid Phase of H2 S/CO2 Coexistence System
For studying the corrosion behavior and mechanism of tubing in high temperature and pressure vapor-liquid phase of H2 S/CO2 coex-istence system, the dynamic corrosion simulation experiment of P110 steel for oil casing in CO2/H2 S coexisting system was carried out using the high temperature autoclave. The uniform corrosion rates and pitting corrosion rates of samples were calculated by the weight loss method, and the corrosion behavior characteristics of P110 steel in liquid phase and gas phase of CO2/H2 S coexistence system were analyzed and studied by XRD, SEM/EDS and 3D optical profile microscope. Results showed that the uniform corrosion rate and pitting corrosion rate of P110 steel in the liquid phase environment were 0.0263 and 0.2081 mm/a, respectively, which were higher than the uniform corrosion rate (0.0148 mm/a) and pitting corrosion rate (0.1569 mm/a) of P110 steel in the gas phase environment. Moreover, the corrosion products formed on the surface of P110 steel in the liquid phase environment were mainly red-brown powdery loose FeCO3 , and the corrosion products formed on the surface of P110 steel in the gas phase were mainly FeCO3 and black-brown dense and uniform FeS. FeS inhibited the further corrosion of the base material from corrosive medium of CO2 , H2 S and Cl. Besides, the corrosion of P110 steel in liquid and gas phases was mainly uniform corrosion, with localized pitting and a tendency towards localized corrosion.
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