Revisiting Precipitation-Hardened Martensitic Stainless Steels for Wireline Service in Highly Sour Reservoirs with Elemental Sulfur (C2026-00014)

Manuel Marya

The sour-service performance of three precipitation-hardened (PH) martensitic stainless steels —17-4PH (UNS S17400) at 115 ksi (793 MPa) and 160 ksi (1103 MPa), and 13-8PH (UNS S13800) at 190 ksi (1310 MPa) specified minimum yield strength — was re-evaluated through three autoclave tests. Despite declining favor for sour applications, these corrosion-resistant alloys have demonstrated long-term success in wireline operations, attributed to short service durations, sub-yield tensile stresses, and improved inspection protocols. This study investigates their stress tolerance under 5-week cyclic exposure to sour environments, with hydrogen sulfide (H₂S) and carbon dioxide (CO₂) partial pressures up to 1000 psi (68.9 bar), temperatures reaching 450°F (232°C), brine pH between 2.75 and 3.50, and optional elemental sulfur (S⁰). Results indicate: (1) extensive pitting, particularly in 17-4PH; (2) 17-4PH at 115 ksi resists sulfide stress cracking up to 40–50% SMYS at pH 3.50; (3) 17-4PH at 160 ksi shows cracking resistance only up to ~35% SMYS regardless of S⁰; and (4) 13-8PH consistently fails beyond ~20% SMYS. These findings underscore the importance of a nuanced understanding of PH martensitic stainless steels to ensure their safe use in sour environments beyond the traditional NACE MR0175/ISO15156 scope.