Environmentally Assisted Cracking Testing of High Strength 15Cr Steel in Sour Well Environments

As a new corrosion resistant alloy (CRA), high strength 15Cr martensitic stainless steel (0.03C-15Cr-6Ni-2Mo-1Cu) offers an OCTG material for the completion of HTHP deep water wells and large bore gas wells, due to a combination of high specified minimum yield strength (SMYS) of 125 ksi without cold drawing, good notch toughness, and superior CO₂ corrosion resistance. This paper describes an experimental investigation of the resistance of 15Cr steel to environmentally assisted cracking in simulated sour oil and gas well environments at three different temperatures including 75°F, 200°F, and 400°F. Multiple heats of this material are tests at the extremes of strength/hardness and minimized alloy content per the alloy specification. The limit of use of the 15Cr steel in sour well environments are presented and discussed in detail.