Initial condition setting with MINC

HI All,

If I activate MINC and set the porosity in the following way, will the porosity apply to both matrix and fracture element?   I use this method to assign the porosity, the result looks right from the interface visualization, however, when I check the INCON file as shown in the section screenshot, it doesn't look right to me.  It looks like the porosity I input only apply to the fracture volume continua, while the matrix continua is zero.    Anyone has any idea please?  Thanks a lot!

 

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  • Wendy,

    I don't see any screenshots (here and in your previous posts), so I don't know what you mean by "the following way". Obviously, the fracture and matrix continua have their own (very different) material properties, which thus need to be specified in separate ROCKS blocks. How the material is assigned in the MINC file is a little strange (elements assigned to material No. 1 in the primary mesh will have materials No. 2 and 3 for the fracture and matrix continua, respectively, in the MINC mesh). If you specify porosity in INCON, it's clearly separate for fractures and matrix as well. My reply is obviously beside the point, as I most likely misunderstood what you actually did.

    Stefan

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  • Hi Stefan, sorry that the screen shot didn't work in the previous post. What I was trying to say is that if I have MINC activate, the way to assign the porosity for matrix continua from the " set cell data" seems not to be working correctly. 

     

     

    For example, after assigning the porosity using " Set cell data", I checked the INCON file and the following shows the result, which the porosity applied to fracture continua instead of matrix continua.

     

    So when we have MINC activate, which is the appropriate way to assign porosity and permeability based on cell (not based on rock type) for the fracture and matrix continua?   Shall we use MINC and INCON file only?  Thanks a lot!

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  • Hi Stefan,

    I did another test using the rock type to define the porosity for both matrix and fracture continua as can be seen below. Here I define 0.2 and 0.1 to matrix and fracture, respectively.

     

    However, when I check the INCON file, it shows that the porosity for both matrix and fracture are all zero.  Can you please help to explain this?   Is there actually a way to assign the porosity and permeability based on cell for matrix and fracture continua?  Thanks a lot!

     

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  • Wendy,

    OK, now I see that you are using PetraSim. I do not know much about PetraSim, but it does the correct thing by setting porosities in INCON to zero, which only means that TOUGH2 takes porosity from the ROCKS block. Feel free to overwrite them in INCON to define element-specific porosities. 

    The actual test to see whether the correct porosities are taken in the simulation is to look at the resulting SAVE file; it will reflect the specified porosities, potentially slightly modified in case you provide pore compressibility and/or thermal expansivity coefficients.

    Element-by-element permeabilities are specified through permeability modifiers, variable PMX, in block ELEME (but I don't know how this is done in PetraSim).

    Please submit PetraSim-related questions to the RockWare Discussion Group at https://www.rockware.com/forum/index.php?showforum=5.

    Stefan

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  • Thanks Stefan for your reply!

    As  you pointed out that if the porosity in INCON file is zero then the porosity is taken from the ROCKS block.  What if in the INCON file, there is porosity value for fracture continua while the porosity for matrix continua is zero.  Does that mean the porosity for matrix will be taken from the ROCKS Block or the porosity for matrix will be taken as zero?  Thanks!

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  • Wendy,

    Yes. For each element, if a non-zero value is given in INCON, that value will be taken; otherwise, the porosity as specified in the ROCKS block is used.

    As suggested in my previous reply, you can easily answer your own questions by checking the SAVE file (you could run the code for a single, tiny time step to see in the SAVE file how your INCON file is interpreted by TOUGH2).

    Stefan

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  • Got it.  Thanks very much Stefan!

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