NACE TM0177 Method D corrosion test is very frequently used for the determination of the fracture toughness of low alloyed steels in sour environments. The use of the standard NACE Solution A environment saturated by 1 bar H2S allows an efficient quality control of OCTG products for order release but does not provide KISSC values for well design in fit-for-purpose conditions. This is more especially true for 125 ksi grade which is essentially used in mild sour conditions. However the definition of the most reliable test condition is still lacking consensus more particularly regarding the appropriate test duration and pH buffering. Consequently an extensive DCB testing program has been performed on 125 ksi grade sour service casing and coupling in 0.07 bar H2S gas for solving these issues and for providing meaningful KISSC values.
Key words: Microbial Influenced Corrosion (MIC), well injection, produced water, biocide, monitoring, QPCR, vPCR, cATP, DNA, RNA, culturing, comparison methods, ultraviolet, chemical free disinfection, field trial.