Synergistic effects of CO2 and H2S on stress corrosion cracking of stainless steel 254SMo in extremely aggressive oilfield environment

Abstract

Synergistic effects of CO₂ and H₂S on stress corrosion cracking of stainless steel 254 SMo in extremely aggressive oilfield environments were explored through experiments and water chemistry modelling calculations. Fracture morphology reveals transition from ductile fracture to plastic fracture characteristics. Initiation of fracture was attributed to pitting corrosion, and depth of the pits was consistent with the Gumbel distribution. Presence of CO₂ and H₂S exhibits a coupling effect on stress corrosion cracking of stainless steel 254 SMo. Ionization of H₂S promoted by CO₂ produced more HS⁻ and S²⁻ with increasing temperature and pressure, accelerated pit generation on the surface, and increased susceptibility to stress corrosion cracking.