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EOS7C WARNING. H2O MASS FRACTION IN THE GAS WAS LESS THAN ZERO IN 1 GRID BLOCKS

Hi All,

I got the error below in running TOUGH3-EOS7C. Any idea how to cope with this?

Thanks,

Haiyan

 EOS7C WARNING.  H2O MASS FRACTION IN THE GAS WAS LESS THAN ZERO IN    1 GRID BLOCKS.
      ( THE SUM OF CH4, BRINE AND NCG AND TRACER MASS FRACTIONS MUST BE LESS THAN OR EQUAL TO ONE. )

5 replies

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    • Staff Scientist
    • Christine_Doughty
    • 1 yr ago
    • Reported - view

    In the past, I have had better success using EOS7C when I specify a very small amount of all components as initial conditions.  I use something like 1e-10 for mass fractions, and it does not change the physics of the problem, but sometimes helps numerical issues like you describe.

      • Haiyan_Zhou
      • 1 yr ago
      • Reported - view

      Christine Doughty 

      Thanks. I tried that but the warnings remain.

    • Staff Scientist
    • Christine_Doughty
    • 1 yr ago
    • Reported - view

    Here are a few things to check:

    Does your grid resolution change too suddenly?  I try to make coarser grid blocks no more than 1.5 times the size of adjacent finer grid blocks.

    Do your injection/production rates change suddenly?  If it makes sense for your problem, try gradually changing rates with MOP(12)=0.

    Try bigger amounts of initial mass fractions: 1e-9 or 1e-8 might help.

    Make error criterion RE1 smaller.  The default is 1e-5.  Try 1e-6.

    Check what is happening in the problem when the error occurs.  Maybe you can make the problem "easier" for TOUGH by making changes more gradual.

    • Haiyan_Zhou
    • 1 yr ago
    • Reported - view

    Sorry I missed the reply. Thanks for the detailed suggestions.

    My grid resolution does change significantly, 100m vs 500m. I will try to modify it later.

    My MOP(12) is already 0.

    I will try the mass fraction.

    I did not change the error criterion RE1 as I am afraid the model will run slower. But I can try.

    Thanks,

    Haiyan

    • Haiyan_Zhou
    • 1 yr ago
    • Reported - view
    Christine Doughty said:
    Try bigger amounts of initial mass fractions: 1e-9 or 1e-8 might help.

     This one works in my model. The warnings are all gone. Thanks!

    Haiyan

Content aside

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