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ECO2N, Model initial temperature distribution

save td_test

Dear all members,

Hi,
I'm working on thermal injection simulation in TOUGH2 and I want to define an initial temperature distribution for my model. After program execution (ECO2N), the pressure distribution is correct but the temperature distribution remains constant. I could not find out the reason. I have attached the input and output files that I tried and I would be grateful if someone can help me on this issue and let me know why this is occurring and how should I modify the input.

4 replies

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

    Hi Ahmad,

    Your temperatures actually did change from the initially specified values (which are slightly different for UPPBC and BASBC). Since you did not specify a constant pressure or temperature boundary anywhere, the temperature throughout the domain becomes uniform at steady state - as expected. I don't know how your domain looks like and what boundary conditions you want (I suppose you wanted to create some geothermal gradient). For elements with prescribed temperature (I presume those belonging to materials UPPBC and BASBC, even though they seem to have variable elevations), set the rock grain density DROK to a very large value (e.g., 1E50) to keep the temperature constant.

    Hope this helps,

    Stefan

      • Ahmad_Zarei
      • 6 yrs ago
      • Reported - view

      Stefan Finsterle 

      Dear Stefan,

       

      Hi,

      Thank you for the information, I really appreciate your help in resolving the problem. The problem was solved by using your suggestion.

      As you mentioned I want to define a geothermal gradient in the model. The model that I defined and tried to test has a very simple geometry. The model consists of three horizontal layers that represent the top rock (20 m), aquifer, and base rock (20 m). One horizontal fractured zone embedded into the aquifer rock mass layer. The aquifer in placed between top and base rocks which are low-permeable rocks. The height and length of the model are 100 meters. The initial temperature and pressure at the top of the model are 64.6° C and 11.77 MPa and at the bottom of the model are 67.9 ° C and 12.75 MPa. In order to define these conditions and getting the initial temperature and pressure distribution, I defined the first row of the base and top rock elements as BASBC and UPPBC.

      However, the problem solved, I want to ask you if this definition is the correct way to define the pressure and temperature boundary conditions.

       

      Best Regards

      Ahmad

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

    Ahmad,

    There is no generally "correct way" to define your system - it depends on how your actual reservoir looks like! I don't know how you specified the hydraulic boundary conditions now, i.e., whether you have no-flow boundaries all around, or a prescribed pressure at the top, or at the top and the bottom. Again, any of these configurations may be appropriate. If you have no-flow boundaries all around, the mean pressure may not be what you want, and you may run into problems once you start injecting or producing from the finite reservoir. If you specify the pressure at both the top and bottom boundaries, you may get a flux across the system, which may (or may not!) be what you want. I suggest checking this. 

    Best,

    Stefan

      • Ahmad_Zarei
      • 6 yrs ago
      • Reported - view

      Stefan Finsterle 

      Dear Stefan,

       

      Thanks a lot for your hints. Actually, for the beginning, I wanted to reach equilibration and initial thermal gradient and check these items and then define injection into the aquifer. I will check all the points that you mentioned for further processes and I hope there is no problem in the model.

       

      Best Regards

      Ahmad

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