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

Abstract The sour-service limits 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 (13-8Mo, UNS S13800) at 190 ksi (1310 MPa) specified minimum yield strength (SMYS), were re-evaluated through three pressurized autoclave tests. Despite declining in sour service, these corrosion-resistant alloys (CRAs) have had long-term success in wireline operations, attributed to short service durations, low elastic tensile stresses, and improved inspection protocols. This study evaluates the safe and allowable tensile stresses for these CRAs under 5-week cyclic exposures to hydrogen sulfide (H2S) and carbon dioxide (CO2), with partial pressures up to 1000 psi (68.9 bar), temperatures reaching 450°F (232°C), and brine pH ranging from 2.75 to 3.50, both in the presence and absence of elemental sulfur (S8), to determine their resistance to cracking. Results indicate: (1) extensive pitting, particularly in 17-4PH at low pH with S8; (2) 17-4PH at 115 ksi resists sulfide stress cracking (SSC) up to 40-to-50% SMYS at pH 3.50; (3) 17-4PH at 160 ksi shows cracking resistance only up to 25-to-35% SMYS regardless of S8; and (4) 13-8PH consistently fails beyond ~20% SMYS, even at pH 3.50 without S8. These findings highlight the critical need for a comprehensive understanding of both PH stainless steels and wireline equipment to ensure the reliable use of these CRAs in sour environments, often extending outside the conventional boundaries set by NACE MR0175/ISO 15156.