Experimental and Numerical Assessments of the Corrosion-Induced Failure of a J55 Tubing in an Ultra-Deep Gas Well

Severe corrosion in the carbon steel tubing led to fluid leakage and reduced output in an ultra-deep gas well. Analysis using microscopy, XRD, and corrosion testing showed that while materials met API 5CT J55 standards, large-scale wall thinning reduced the tubing’s pressure tolerance below service conditions. Corrosion products included FeCO₃ and Fe₃O₄, with protective scaling layers of CaCO₃ and crude oil residues. Once disrupted at depth-specific pH and hydrodynamic conditions, the corrosion of the tubing accelerated. Simulations of the localized corrosion rate showed peaks in the first 30 days due to high CO₂, low pH, and increased flow-induced shear stress.