The use of culture-based microbiological methods is slow and can only measure the few sulfate-reducing Bacteria (SRB) that can be cultivated. Faster and more accurate techniques for the diagnostics of microbiologically influenced corrosion (MIC) are therefore required.

This paper demonstrates the benefits of applying state-of-the-art molecular microbiology methods (MMM) to the identification and quantification of the microorganisms contributing to corrosion in oil production facilities. For quantification of troublesome microorganisms MMM can be applied directly to solid samples from the oil field without the need for culture media.

The corrosion mechanism was investigated in two different cases: (i) a piece of piping with high corrosion rates from the water outlet of a separator from the Halfdan oil field, and (ii) a similar piece of piping from the Dan oil field with much lower rates of corrosion. The chemical distribution of elements was analysed using X-ray diffraction and the levels of MIC causing microorganisms were determined with qPCR (a DNA-based quantification method).

The results showed that corrosion in the piping from Halfdan was caused by MIC. The results also showed that not only SRB were involved in the observed MIC. High numbers of sulfate-reducing prokaryotes (SRP) and methanogens were measured in material from the Halfdan separator with high corrosion rates. The methanogens were particular abundant close to the metal/scale interface. The data indicates that the high level of microorganisms in the Halfdan separator speeds up the corrosion process by efficiently consuming hydrogen released during dissolution of iron.

Finally, the paper discusses the strength of applying qPCR as a standardized, high-throughput routine monitoring tool for MIC diagnostics when developing more reliable integrity management programs in the future. This study has shown that the improved molecular microbiological approach to MIC is important when designing and testing remedial actions towards MIC in oil field systems.

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