Stress Corrosion Cracking occurring in packer fluids is a growing problem for oil and gas production. There are many factors that affect the SCC downhole applications. Until recently however, there have been few published studies that evaluate the interaction of packer fluids and martensitic stainless steels.

The effects of steel chemistry, composition of fluid and environmental factors on SCC performance of martensitic stainless steel OCTG in the clear brine environment were studied. The combination of sodium thiocyanate and ammonium bisulfite was much more likely to induce SCC than the combination of amine based inhibitor and sulfur free oxygen scavenger. The leakage of CO2 and/or H2S into the packer fluid significantly accelerates the occurrence of tubing SCC. In the presence of thiocyanate ion the SCC susceptibility in the CaCl2 packer fluid was higher than in the CaBr2 fluid of same density. However, there was no significant difference in the critical halogen ion content for SCC between CaCl2 and CaBr2 solutions. In general, Zn based fluids prevented the occurrence of SCC in the packer fluid environment. Modified 13Cr-1 steel pipe with 1% Mo showed higher susceptibility for SCC than modified 13Cr-2 and new 15Cr steel pipe with 2% Mo.

The SCC occurs at high temperature and is accelerated especially in the anodic polarization condition. It seems that the mechanism for the SCC phenomena of martensitic stainless steel in the packer fluid is an active pass corrosion(APC) type SCC.

Subject
Sulfur, Piping, Halogens, Thiocyanate, Oxygen scavengers, Steel pipes, Amines, Fluids, Corrosion inhibitors, Steel, Stress corrosion cracking, Martensitic steel, High temperature
Keywords:
martensitic stainless steel, stress corrosion cracking, packer fluid, corrosion inhibitor oxygen scavenger, carbon dioxide, hydrogen sulfide
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2006
Association for Materials Protection and Performance (AMPP)
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