Failure Analysis of Well-Logging Steel Wire in a Gas Injection Well

The fracturing of well-logging steel wire occurred during downhole operation in a gas injection well in China. The failed well-logging steel wire material was austenitic stainless steel manufactured by cold drawing. In this study, the failure cause was investigated based on visual inspection, chemical composition analysis, metallographic observation, mechanical performance testing, SEM and EDS analysis. The results showed that the failure reason was primarily Cl−-induced stress corrosion cracking which made the steel wire unable to bear the normal load of well-logging operation. The steel wire had experienced SCC during previous operation in a production well where downhole mediums contained high Cl− concentration, and then cracks-containing steel wire was used for this operation. Most of the cracks initiated within surface scratches caused by cold drawing where corrosion pits were present. In addition, cold drawing process of steel wire had a significant influence on SCC propagation mode, and the secondary cracks mainly extend along deformed austenitic grain boundaries in cold drawing direction.