Abstract
Super martensitic stainless steels (13Cr and 15Cr steels containing Ni and Mo) were developed for OCTG (Oil Country Tubular Goods) materials for high temperature sweet (slightly sour) environments. Corrosion performances of these CRAs (Corrosion Resistant Alloys) were evaluated and compared with those of 13%Cr and 22Cr duplex stainless steels for high temperature sweet gas environments, such as those in Minami-Nagaoka wells, based on application temperature limits claimed by steel makers and actual field results of 13%Cr tubing strings.
The test results were compared with the evaluation results by J-Tube Mate (Corrosion performance evaluation software) and effects of acetic acid, formation water production (high Cl- concentration) at high temperatures were discussed. Effects of alloying elements such as Cr and Mo on pitting potential at ambient temperature were also discussed.
