Corrosion failure analysis of gas pipe on the gas wellhead in the Right Bank of the Amu Darya River

The CO₂ partial pressure in the B gas field on the right bank of the Amu Darya River is 0.6 MPa, and the inner wall of the throttling section of the gas production wellhead is seriously corroded. Electron microscopy, energy spectrum analysis, XRD composition analysis, metallographic analysis, hardness analysis and dynamic analysis were carried out. The results show that the main component of corrosion is FeCO₃, containing other components such as Ba and Si. The hardness of the corroded pipe meets the material performance requirements, and natural gas contains acidic components such as CO₂. The main reason for the failure of the pipe is that the CO₂ in the natural gas leads to electrochemical corrosion on the inner wall of the carbon steel pipe under suitable temperature and humid conditions, and the throttling effect causes a strong scouring effect of the fluid, contributing to the failure of the formation of protective film on the inner wall of the throttling pipe section by corrosion inhibitor, with the difficulty of corrosion product to form a complete film. The sediment carried by the fluid from the bottom of the well intensifies the erosion of the throttling pipe section, which forms an erosion pit, and the metal of the inner wall of the pipe is exposed to a corrosive environment, increasing the corrosion rate greatly. Suggestions for the treatment of corrosion-resistant alloy surfacing materials have been proposed.