Effect of Total Pressure on the Corrosion Behavior of L360NS Steel in the CO2/H2S/O2 System

In order to clarify the effect of total pressure on the corrosion behavior of steel in the CO2/H2S/O2 system, the high temperature and high pressure reaction vessel, scanning electron microscope and its accompanying energy spectrometer, X-ray diffractometer, 3D optical profiler, and other instruments were employed to research the effect of the different total pressur on the corrosion behavior of L360NS steel in CO2/H2S/O2 system. Results showed that when the total pressure changed within the range of 0.2~1.5 MPa, the uniform corrosion rate of L360NS steel increased with the increase of total pressure. The reason might be that the increase in total pressure led to an increase in gas content in the solution, which accelerated the corrosion reaction kinetics and exacerbated corrosion. Moreover, the bottom of the corrosion product film was a mixture of wedge-shaped and granular products, while the surface was granular. The product composition was FeCO3, Fe2O3, FeS, and FeS2. Besides, with increasing the total pressure, the number of corrosion pits increased in the form of vertical and horizontal extension, and the local corrosion degree became deeper, which was due to the uneven protection of the substrate by corrosion products such as FeCO3, Fe sulfides, and Fe2O3 oxides.