Implications of Temperature and Buffering Systems for Laboratory Testing of Alloy Steel and 13Cr Materials in Oil and Gas Production Environments

This paper describes the results of a laboratory study evaluating cracking resistance of 4130, 13Cr-L80, 13CrS-110, and HP2-110 materials in three different oil and gas well environments.  Sulfide stress cracking resistance was evaluated using tensile specimens stressed to 90% actual yield strength and double cantilever beam specimens.  Three environments were evaluated that included: (a) NACE Solution A with 15 psia H₂S; (b) a simulated oil well with 100,000 mg/L Cl^-, pH 4.5, 0.5 psia H₂S; and (c) a simulated gas well with 1,000 mg/L Cl^-, pH 3.5, 0.5 psia H₂S.  These three environments were further varied by evaluating at room temperature and at 40 F.  Also, the oil well and gas well simulated environments were tested using both an acetate and bicarbonate buffer solution for pH control.  

Cracking and corrosion observations are reviewed and implications of alloy sour service limits, effect of temperature, and effect of buffering agent in laboratory testing are discussed.  Findings of the current study are compared with previously presented studies to confirm or challenge assumptions on the role of temperature and buffering systems.