H2S Levels in Natural Gas 1

[Trond]

Hi everyone,

We have offshore oil & gas platforms with some wells producing H2S. Recently it was found that one of our wells had reached 600 PPM H2S. We do not have H2S detectors on the platforms, and the well was therefore shut down. This to me seems a bit excessive. Whereas 600 PPM H2S inhaled will lead to rapid loss of conciousness, so will inhaling of pure natural gas!

Considering that these are wells in a well ventilated area, and any major releases would be picked up by inline pressure alarms and gas detectors in the area, would it not be safe to keep the system running with a H2S concentration of even more than 600 PPM?

Eagerly awaiting your words of wisdom

Trond

 

[Cmo]

Important,
Thanks for the info re your gas specs.
What Trond mentioned above is what I do. Chemical Engineer for a Canadian chemical company specializing in H2S sweetening. While your H2S concentration is feasible to treat via scavenging technology your volumes(200MMscfd) are significant. Ball park $/mcf to treat something along those line would be $2.5/mcf (cdn). In the past this same technology has been used to treat sales gas in the 1% range however it was associated solution gas, which meant the economic driver, was the oil not the gas itself. Further with smaller volumes (vent gas off of produced liquids) we have gone as high as 34%. This large concentration was treated for safety only since it is uneconomical.
Capital would be relatively marginal compared to op cost ~$250k, unless you could inject into the pipeline as per Trond however this may affect the above $/mcf.
I expect (and would recommend) you going into some sort of amine plant with those volumes.
So you know the relationship is linear with respect to H2S. Trond's 600 ppm would be closer to $0.3/mcf (cdn). These #'s are a little more feasible and inline.
You can contact me directly if you need some more direction. I'm not familiar with offshore applications but the same principles should apply as to the Western Canadian Sedimentary Basin. Hope this helps.
Regards,
CMo
chrismor@telusplanet.net

 

[ggordonstewart]

You have a very serius safety issue that you seem to want to ignore. Just because this is SE Asia, it does not mean that you should be prepared to endanger the life and health of the crew. Extreme safety precautions should be exercised in any H2S environment. Every year people die or are seriously affected by H2S because someone did not take adequate precautions. Personally, I would not step on a platform that was operated with so little concern for safety as you demonstrate.

G. Gordon Stewart, P.Eng.
Gas & Oil Process Engineering Consultant

http://www.ggordonstewart.com/

ggstewar@telusplanet.net

 

[Trond]

Dear Gordon,

first of all, the problem was not ignored, the well has been shut in and is no longer in production. I was asked by a poster if the platform was in US waters, and replied that it was located in SE-Asia. I am not too sure what you are insinuating, but you seem to be making way too many assumptions and accusations here. Next time I suggest you try to read the thread before jumping to conclusions.

Having a bad day in the office perhaps?

Trond

 

[MAJOSA]

Check out "

http://www.zeolife.co.uk"

they have a small article on their web site dedicated to H2S removal using Natural Zeoliteand can offer engineering solutions for your requirements and eliminate your problem at source.