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initialization of water composition

Hi,

Recently, I tried to use toughreact (EOS1) to simulate fluid-rock interaction including dissolution and precipitation. But it always reminded me “convergence problem in initialization of water composition”. I tried to use PHREEQC to balance the meteoric water (from published article) and minerals, then input the parameters to tough     react. It still remined me same error. I find no way to continue my research, please the specialists can provide help for me.

Posted files are 1D baisc files from toughreact332.

Best regards.

3 replies

null
    • TOUGHREACT Developer
    • Eric_Sonnenthal
    • 4 mths ago
    • Reported - view

    Hi,

           The chemical inputs may not be possible. You have  7 molal Na+, which is well outside the range of Debye-Huckel. There is 3.53 M so4-2, but the guess is only 6.36E-04. Having guesses very different than the actual species activity will make convergence very difficult. The guess for SiO2 (aq) is 4 orders of magnitude smaller than the total, which also will not work. The guesses should be close to the total except for some redox species, Al, and Fe usually which can be very low if there are other complexes. Also you have listed nearly every secondary complex in the database. I would remove all of those and let the code pick them first. 

    Balancing the charge will not really make a difference in TOUGHREACT since it works on mass balance. Ideally the water should be balanced from the measurement, but the code will just try to keep mass balance not charge balance (technically, these will be the same).

    ca+2         1   2.56E-03       4.20E-03       *      0.0
    mg+2         1   2.12E-03    3.40E-03       *      0.0
    na+         1   6.27E+00    7.05E+00       *      0.0                            
    k+         1   4.77E-07    5.43E-07       *      0.0
    hco3-         1   3.12E-07    1.73E-03       *      0.0
    so4-2         1   6.36E-04    3.53E+00       *      0.0
    cl-         1   1.04E-04    3.35E-04       *      0.0
    h+         1   7.93E-09    7.93E-09       *      0.0
    sio2(aq)     1   4.82E-09    2.67E-05       *      0.0
    h2o         1   1.00E+00       1.00E+00       *      0.0
    alo2-         1   3.64E-11    2.02E-07       *      0.0
    fe+2         1   1.00E-15    1.00E-10       *      0.0    

    regards,

    Eric

      • Merson
      • 4 mths ago
      • Reported - view

       

    • Merson
    • 4 mths ago
    • Reported - view

    Hi,Eric. Thanks for your suggestions.  I successful solve this priblem and run my model during 20Ma.  But I notice the warning messages in "runlog.out" (Species: mg+2      Relative error = 8.848E-02 Tolerance= 1.000E-03 Program execution was not aborted. Check results!). Could you can give me some suggestions?

Content aside

  • 4 mths agoLast active
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