MIC Corrosion Wet Gas

[ing_arg]

I am analyzing a wet gas pipe whose fluid comes from the upper outlet of a three-phase separator, followed by two compression phases. In the water extracted from the triphasic separator, the presence of APB and SRB bacteria was detected. Is the presence of bacteria a threat to the wet gas pipe? Are they able to be transported together with the gaseous phase and then grow from the condensed water?

Thank you!

 

[SJones]

The bacteria aren't a threat in themselves, the interaction with other corrosion mechanisms is. But, you say that you are collecting water from a wet gas pipe (even after two stages of compression - probably with three scrubber vessels minimum), so one would expect some form of corrosion control is being instituted to take care of matters.

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.

 

[ing_arg]

Steve thanks for your reply. The study is pre-operational and the simulations reflect the condensation of water inside the line with water hold up of up to 50% at low points. Regarding other damaging agents in the system, only the presence of CO2 is expected with a concentration of 6% molar

The use of periodic cleaning pigs is foreseen but I had doubts as to whether the microbiological issue should be considered (use of biocides) due to the absence of liquid water at the outlet of the separator. According to my previous ideas the bacteria could not be transported together with the gas phase but I wanted third opinions. Thank you very much for answering!

 

[EdStainless]

Is there risk of water accumulating anywhere along the pipeline? if so then you need to plan for MIC control.
The bacteria will easily be transported in damp gas.

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P.E. Metallurgy, consulting work welcomed

 

[ing_arg]

Ed thanks for your reply. Do you have any paper to share with me regarding this issue? I was looking for days and all I find are failures associated with pipelines with production water inside. I could not find a single failure analysis in wet gas ducts where the water inside comes from condensation. Also i did not find any publication associated with MIC failures in dry gas pipelines, which is possible according to the reference standard (NACE TM0212)

 

[SJones]

NACE Corrosion 2004, Paper 04592
NACE Corrosion 2016, Paper 7194

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.

 

[CH. Lee]

thumbs up for the efforts to sample for APB and SRB in the produced water; the 3-phase separators are normally equipped with demister at the gas outlet, there are changes mists and droplets of liquid can be carried over into the gas phase, in theory, the bacteria can grow and colonise in this gas pipe, however, as the wet gas passes through the scrubbers, compressors and aftercoolers; changes of the presence of bacteria in a compressed gas is essentially zero (bacteria are not air-borne, even if they do for a short distance, the high temperature in compressors would eradicate them). Unless there is entry point of contaminant via ingress of water or chemical injection, or condensate is spiked back with the gas prior to exporting the dried gas in the pipeline; but changes are not high in my opinion.

Presence of bacteria in the production fluid is alarming, though not uncommon. I would be investigate the source and cause of these bacteria in the production fluids. Contamination in reservoir is more alarming to me.

CH. Lee, PhD P.E
Lead Materials and Corrosion Engineer
Intecorr Consultancy

http://www.intecorr.com

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