The Fracture Reason of Repaired Tubing in a Western Oilfield

The fracture reasons for repaired tubing in a western oilfield were systematically analyzed by means of nondestructive testing, chemical analysis, metallographic observation, mechanical property testing, fracture analysis, crack analysis and corrosion product analysis. The results showed that the failure of repaired tubing was caused by stress corrosion cracking. Before the tubing was repaired, stress corrosion cracks had existed on the internal surface of tubing. By the influence of stress and high CO₂ and Cl^- content in injected waste water, the cracks expanded and thus caused the tubing fracture in later service.