TOUGHREACT/EOS5 serpentinization
Hello All,
Is TOUGHREACT / EOS5 able to simulate the process of serpentization that can lead to the production of natural hydrogen?
I know that EOS5 is intended for transporting hydrogen in the aquatic environment, but I wonder if it is possible to simulate hydrogen generation in situ.
Kind regards,
Maciej
2 replies
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Hi Maciej,
Thanks for your question — I’m also interested in this topic. I was wondering if you actually managed to model hydrogen generation via serpentinization using TOUGHREACT/EOS5.
I ask because I’m planning to use TOUGHREACT/EOS5 for a natural H₂ generation study myself and would love to hear about your experience.
Kind regards,
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Dear All,
I would like to post here an email with detailed response I received from Dr Eric Sonnenthal via a private communication some months ago.
Basically, TOUGHREACT can simulate hydrogen generation with any EOS module because it is generated through chemical reactions. If it is a small amount of hydrogen and is completely dissolved, then any module could be used. If there is a separate gas phase already (e.g., water vapor, CO2, air) as in EOS1, EOS3 or ECO2n, and the H2 created is only a few percent or less of the gas phase then EOS5 is also not needed, because the H2(gas) will not significantly affect the gas pressure. EOS5 would only be needed if a separate H2-rich gas formed, or the dissolved H2(gas) affected the fluid density, which is probably not a strong effect.
Unfortunately, EOS5 has not really been tested sufficiently for H2 generation/consumption, because we have not had any projects where we needed to consider that case. I just tried it, and there are some issues that need to be fixed with regard to the coupling. In strongly coupled cases, the chemistry will work fine, and the EOS will work fine, but the difficulty is in the flow taking a source term from the chemistry, and causing the system to go from single phase water liquid to 2-phase water + H2(gas). As you know from using TOUGH2, it has troubles with these phase transitions even without any chemistry, so when it is applied as a source term in the next time step it is even more challenging numerically.
Definitely you could use TOUGHREACT v4.13 for serpentinization and H2 generation using EOS1, EOS7, or one of the other modules, given the constraints/assumptions described above, but EOS5 looks like it needs some modifications and more testing. Since H2 is a very popular topic now, hopefully we can make some updates to TOUGHREACT in our next release sometime this year.
Best regards,
Maciej