A 125 ksi grade high strength low alloy steel OCTG has been developed for mildly sour environments. This has been used for a “Fit For Purpose” production casing material in high pressure / high temperature wells.

In this paper, the prevention of oxygen ingress and pH stabilization during testing have been investigated for obtaining accurate SSC test results by NACE TM0177-2005 Method A in mildly sour conditions. Testing techniques have been developed in which the test equipment is contained within a nitrogen chamber and the test pH is stabilized by using an acetic acid / sodium acetate buffering system.

The SSC resistance of 125 ksi grade high strength low alloy steel has been evaluated using the above mentioned testing techniques under various H2S partial pressure and pH conditions. The SSC resistance limits are discussed in the relationship between H2S partial pressure and pH.

Subject
Test methods, Contamination, Sodium chloride, Acidity, Sodium chloride solution, Solutions, Bubbling, Nitrogen, Oxygen, Dissolved oxygen, Sulfide stress cracking, Hydrogen, Low alloy steel
Keywords:
sulfide stress cracking, low alloy steel OCTG, hydrogen sulfide, hydrogen
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2010
Association for Materials Protection and Performance (AMPP)
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