Effect of CO₂/H₂S and Applied Stress on Corrosion Behavior of 15Cr Tubing in Oil Field Environment

• Main Authors: Xuehui Zhao, Wei Huang, Guoping Li, Yaorong Feng, Jianxun Zhang
• Format: Article
• Language: English
• Published: MDPI AG 2020-03-01
• Series: Metals
• Subjects: tubing steel; stress corrosion cracking; high-temperature/high-pressure; pitting corrosion
• Online Access: https://www.mdpi.com/2075-4701/10/3/409
• ISSN: 2075-4701

The corrosion behavior of a 15Cr-6Ni-2Mo martensitic stainless steel (15Cr stainless steel) in a CO₂/H₂S environment was investigated by conducting high-temperature/high-pressure immersion tests combined with scanning electron microscopy and metallographic microscopy. The presence of H₂S decreased the corrosion resistance of the 15Cr tubing steel. The critical H₂S partial pressure (<i>P</i>_H2S) for stress corrosion cracking in the 15Cr tubing steel in the simulated oil field environment with a CO₂ partial pressure of 4 MPa and an applied stress of 80% <i>&#963;</i>_s was identified. The 15Cr tubing steel mainly suffered uniform corrosion with no pitting and cracking when the <i>P</i>_H2S was below 0.5 MPa. When the <i>P</i>_H2S increased to 1 MPa and the test temperature was 150 &#176;C, the pitting and cracking sensitivity increased. The stress corrosion cracking at a higher <i>P</i>_H2S is attributed to the sulfide-induced brittle fracture.