Assistance Needed with Methane Volume Quantification in EOS7C Model
Hello,
I am currently using EOS7C to model the development of a gas bubble gas beneath a low-permeability hillslope. With initial guidance from a previous forum question answered by , I was able to develop a base model for hillslope flow, which I have since modified to better suit my specific needs.
I am encountering a challenge in quantifying the volume of methane within each cell. The model utilizes a two-phase version of EOS7CA, where methane is modeled as a source rather than being injected via a well. I have assigned a constant flux of 1.48E-7 kg/s of methane to each cell.
Is there a method to quantify the mass fraction of methane within the cells? Additionally, does the parameter SAT_G represent a combination of both methane and air gas saturation, or does it exclusively pertain to methane?
Also, is there a way to quantify the methane coming out at the surface?
Thank you for your assistance.
Best regards,
5 replies
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Jordon,
I'm not a specialist in EOS7CA, but:
- Sat_G should be the gas saturation of the gas phase, which includes methane, air and water vapor.
- the concentration of methane in both gas and aqueous phases should be printed in the output file.
- to know how much CH4 is contained in each grid block you should basically use the CH4 mass balance equation, also used by sub BALAN. You need the element volume, porosity, phase saturations and densities, and the methane mass fraction in both phases.
- fluxes of methane through a given surface may be more complicate. Gas and Aq. phase mass fluxes through connections can be printed in the output file. I do not know if EOS7CA prints directly the CH4 fluxes, otherwise they need to be computed using the methane concentration in the upstream element of each connection.
The issue is to select the right connections. Others can for sure be more specific than me. Not sure if COFT can be the right choice for TOUGH3.
Regards,
Alfredo
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Jordon,
I believe Alfredo have answer most of your questions. I would like to provide some supplements. COFT works for printing flux between user specified connections. You can control which flux (phase flux or component flux) to be printed through input of COFT.1 (ICOFTF). For using COFT, you have to find all the connections between elements in model domain and the surface elements.
TOUGH3 newer version (V1.1 or V1.11) provides output for fluxes between two rocks through keyword ROFT. It may be relatively easy for writing out flux to surface, if you define the rocks in specific way.
EOS7CA was designed for applications with low temperature and pressure. It uses Henrys' Law for solubility calculation. If your model involves more complicated flow system, I would suggest use the EOS7MG which is included in V1.11.
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Thank you both, I will work on it this weekend and let you know what I come up with!
Very much appreciated!