Major corrosion factors in the CO 2 and H 2S coexistent environment and the relative anti-corrosion method: Taking Tazhong I gas field, Tarim Basin, as an example

摘要

Anti-corrosion techniques are studied to deal with the CO2and H2S coexistent environment of the Tazhong I gas field. Orthogonal experiment with five different factors and levels is carried out to compare the influence of the factors on the corrosion rate of the sulfur-resistant tubing. These five factors are pressure of CO2, pressure of H2S, temperature, content of Cl?, and water cut. It is found that CO2pressure is the major corrosion factor. The combination of sulfur resistance tubing and corrosion inhibitor is selected as the anti-corrosion method and the proper corrosion inhibitor named YU-4 is designed according to the result of orthogonal experiment. This anti-corrosion method was used in 12 wells of the Tazhong I gas field, achieving good results. The average corrosion rate of Well TZ83 decreased from 1.23 mm/a to 0.025 mm/a and the corrosion rate of Well TZ623 decreased from 0.370 mm/a to 0.016 mm/a.