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(ECO2N)CANNOT FIND PARAMETERS AT ELEMENT * *, for help

Hi,dear all, I'm here agian.
I was puzzled by a question for a long time, I appreciate anybody can provide some suggestion.
I have attached my input file, MESH,INCON,and the output file, and the errors I find is always:

 +++++++++   CANNOT FIND PARAMETERS AT ELEMENT *B41 1*          XX(M) = -.796759E+06 0.000000E+00 -.773195E+03 0.489503E+02 
 +++++++++   CANNOT FIND PARAMETERS AT ELEMENT *AU115*          XX(M) = 0.112248E+09 0.000000E+00 0.271335E+01 0.476544E+02
 +++++++++   CANNOT FIND PARAMETERS AT ELEMENT *AU133*          XX(M) = -.116330E+09 0.000000E+00 -.403902E-02 0.476544E+02
 +++++++++   CANNOT FIND PARAMETERS AT ELEMENT *AU134*          XX(M) = 0.220094E+09 0.000000E+00 0.184769E+01 0.476544E+02
...
The P is a negative value sometimes, and some pressure is more than 60Mpa, I don't know why this situation occurs.

the gravity equilibration is done, and in the INCON I have  provided information ahout parameters,for example:
B41 1           0.39996211E+00
 0.1478955424316E+08 0.0000000000000E+00 0.0000000000000E+00 0.4895031444901E+02
AU115           0.39986379E+00
 0.1424320328248E+08 0.0000000000000E+00 0.0000000000000E+00 0.4765435443686E+02
AU133           0.39986379E+00
 0.1424320322819E+08 0.0000000000000E+00 0.0000000000000E+00 0.4765437272453E+02
AU134           0.39986379E+00
 0.1424320322509E+08 0.0000000000000E+00 0.0000000000000E+00 0.4765436247679E+02
...

and it stopped before the set simulation time. 
I'm a beginner, can anybody help me?

5 replies

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    • George_Pau
    • 8 yrs ago
    • Reported - view

    The above can happens when the operating range of the problem is beyond the specified range of the ECO2N.  From the screenshot it appears to recover after reducing the timestep.  The above warning is not the reason that the simulation ended before the specified time.

    The reason it stopped is below (found in the output file)

     +++++++++ CONVERGENCE FAILURE ON TIME STEP # 321 WITH DT = 0.709277E+03 SECONDS, FOLLOWING TWO STEPS THAT CONVERGED ON ITER = 1
               STOP EXECUTION AFTER NEXT TIME STEP
     +++++++++ REDUCE TIME STEP AT ( 321,  9) ++++++++++++++++   NEW DELT = 0.177319E+03

     

    One of the potential reason is it has reached the steady-state.  I do not know your problem but if that is not a likely scenario, then you will have to examine your solutions to determine whether they are reasonable.

    • sawyer
    • 8 yrs ago
    • Reported - view

    Thank you George. I will examine my simulation according to your advice, thanks again.

    • sawyer
    • 8 yrs ago
    • Reported - view

    Hello George and anybody, there are still a lot of "mistakes" about "CANNOT FIND PARAMETERS AT **",
    I wonder if they will affect the results of the calculations?
    and I don't know how to judge whether the state is steady?
    Thanks!

    • Finsterle GeoConsulting
    • Stefan_Finsterle
    • 8 yrs ago
    • Reported - view

    Sawyer,

    The "CANNOT FIND PARAMETERS" statement just means that the nonlinearity in the system is too strong at the current time step, so that the Newton-Raphson update proposes a set of primary variables that is outside the valid range for calculating thermodynamic properties. TOUGH2 then automatically cuts the time step and tries again, i.e., the primary variable set causing the message is discarded and not used at all. So far, no cause for concern - except that your time steps get smaller.

    If you want to address that issue, you have to do what I described multiple times in this Forum:

    (1) Read your output file carefully (in your case, you would find - unrelated - issues about the use of an undefined material in the MESH file that throws out elements and connections).

    (2) Check which element causes the time-step reduction.

    (3) See what is special about this element (in your case, it is at the boundary between a single-phase and two-phase zone).

    (4) Think about what makes the phase change so difficult (it often points at parameters in the relative permeability and/or capillary pressure function). Try to fix it. This is obviously the difficult, but necessary step.

    (5) I shouldn't mention this, because it only distracts you from the necessary step (4), but you may also play with convergence parameters (MOP(21), RE1, RE2, WNR, etc.).

    (6) Finally, checking whether the state is steady is very straightforward for static systems (no flow everywhere), straightforward for simple systems (possibly the one you are looking at: uniform volumetric flow everywhere), and not so trivial in complex situations. In your case, I don't think you have reaches steady state (but then, I have not analyzed it in detail).

    Good luck!

    Stefan

    • sawyer
    • 8 yrs ago
    • Reported - view

    Thank you Stefan, it really helpful for me!

Content aside

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