Analysis of corrosion failure and materials selection for CO2–H2S gas well

• Published in: Journal of natural gas science and engineering Vol. 86; p. 103734
• Main Authors: Zeng, Dezhi, Dong, Baojun, Zeng, Feng, Yu, Zhiming, Zeng, Wenguang, Guo, Yujie, Peng, Zhengde, Tao, Ye
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.02.2021
• Subjects: CO2-H2S corrosion; Failure analysis; Gas well; Materials selection; Residual corrosion life; CO2-H2S corrosion; Gas well; Materials selection; Residual corrosion life; Failure analysis
• ISSN: 1875-5100
• DOI: 10.1016/j.jngse.2020.103734

This paper analyzed the failure of gas wells in Northwest Oilfield and provided corresponding methods to solve the issue. In order to thoroughly investigated the failure factors, methods used in the experiment were material performance testing, SEM, EDS and XRD. Besides, a self-designed HTHP autoclave was used to simulate the real corrosion environment and thereby a new method to choose suitable materials was proposed. The experimental results showed that the chemical composition, metallographic structure, hardness, microstructure and non-metallic inclusion of the failed tubing were all qualified. As a matter of fact, the failure was caused by water-accumulation corrosion which occurred at 6447 m at the bottom of the wellbore, and by water-carrying corrosion occurred at 5086.4m. This paper concluded that the P110ss steel should be selected as tubing in the failed well at a depth of 5086.4m and nickel base alloy steel should be selected at 6447m. •Causes of gas well failure were analyzed and water-accumulated corrosion and water-carrying corrosion were defined.•A new high temperature autoclave was designed to simulate water-carrying and Water-accumulated corrosion in wellbore.•Suggestion of a material-selection method considering residual corrosion life.