The failure of a J55 steel grade 178 mm (7 in.) production casing in gas storage well was investigated
using a multi-disciplinary approach. The rupture of the production casing was due to the metal loss by
corrosion with striated longitudinal grooving. Since the morphology of the striated grooves could not
solely be used to establish a microbiologically influenced corrosion (MIC) mechanism, the combined
metallurgical, chemical, and biological analyses were used. Scale samples were collected during
casing extraction for composition and biological analyses. Corrosion features and corrosion deposits
were characterized using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS),
X-ray diffraction (XRD), and Raman spectroscopy. Detailed examination of tunnel type corrosion
features was done using a combination of focused ion beam (FIB) for in situ micro-sectioning and/or
micro-metal removal, SEM, and EDS analyses. Most probable number (MPN), quantitative polymerase
chain reaction (qPCR), and microbiome population analysis by 16S, archaeal, and 18S amplicon
sequence analysis were used to identify the microbes abundantly present in the failed well. A broad
study involving other wells in the field lead to the conclusion that at some stage in the period of over 60
years of the life of this well, the activities of the methanogenic archaea caused the observed localized
corrosion leading to the production casing rupture.