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Alison

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Everything posted by Alison

  1. The simple answer to your question is that PetraSim uses a rectangular grid. The grid spacing does not need to be. In addition, the user can set some cells to "disabled" either manually in the grid editor or using contour files. You can see images of such files at http://www.thunderheadeng.com/category/petrasim-gallery/ However, the underlying grid is still rectangular. The reason for using a rectangular grid is that TOUGH2 uses the Integrated Finite Volume approach. To satisfy convergence criteria, the grid must be a "voronoi grid". Essentially, this means that cell volumes must be defined by planes normal to lines drawn between the centers of adjacent cells. The simplest grid that satisfies this criterion is a rectangular grid. The use of rectangular grids is implied, for instance, by the fact the TOUGH2 expects only ks, ky, kz, not a full permeability tensor.
  2. Is it possible to create or work with a non-rectangular mesh in PetraSim?
  3. This depends. If Xair is close to 1.0, then it represents a gas volume. If Xair is nearly 0.0 (for example 1.0E-5), then it is the dissolved air in the liquid phase. TOUGH2 expects realistic inputs, so for the single phase condition it would not make sense to set the air mass fraction to 0.5.
  4. If Xair < 0.99, does this fraction then represent a certain gas volume in gas phase (equal to the gas saturation in the two-phase mode) or is it dissolved in the liquid phase?
  5. In a single phase system with Xair=0.99 then the mass fraction of gaseous water is 0.01. In our experience, TOUGH2 is more stable if a small amount of water vapor is present in the gas (which is also the realistic case). The Brine mass fraction is 0.0 since the salt does not evaporate.
  6. In problem 6 in the TOUGH2 manual (Eos 7), I can choose between single phase (either liquid or gaseous) and two phase flow. However, I am a little bit confused. It is said that for a single-phase system one has to set: e.g. Xbrine = 0, than it's a single-phase system without brine. Xair = 0.99, than it's single-phase gas system. Why don’t we just set Xair=1?
  7. I suspect that a graphic problem is causing most of your hang ups and slow behavior. You can look for new display drivers at http://www.nvidia.com. Try to find the newest driver possible for your graphic card. With 64 MB of display RAM, I would suggest running at around 1280x1024 resolution with 16-bit color.
  8. I’m running a computer with a fast processor and plenty of RAM and am still have problems with visualization in PetraSim. Do you have any suggestions for things to check on this?
  9. There is no size limit in PetraSim. The TOUGH2 executable that we ship with PetraSim has a default limit of about 25,000 cells, but we will provide a larger executable if desired. (TOUGH2 uses the old Fortran approach where the size is fixed during compilation. We do not send everyone a large executable because that changes memory requirements.)
  10. What is the upper limit for the size of a TOUGH2-problem in Petrasim?
  11. To correct the error message "Unable to Write CO2TAB" copy the CO2TAB file from the c:\program files\petrasim\t2react folder into the c:\program files\petrasim folder. There is a known issue where the installer may not include the file in both places.
  12. When running Example Problem 5, after running the analysis by selecting Analysis/Run a message occurs "File Write Failed" "Unable to Write CO2TAB".
  13. The PetraSim version of TETRAD supports wells in the following ways: 1. Reading of wells from CTR files. 2. Display of wells in the model and optionally in the 3D results view. 3. Writing of the TETRAD well !&# data files. The well input format in the CTR file follows Appendix G of the InterSim manual. An example file is given below. Do not include any of the input after and including the !. Example of input of 2 wells ! Line 1 - Title <top origin> ! Line 2 - Orientation (required as given) 2 ! Number of wells RRG-1 ! Name of first well 1 ! Number of subsegments (required to be 1) 3 ! Number of coordinate input lines 12959 8383 -4836 ! Coord 1 12959 8383 0 ! Coord 2 12959 8383 150 ! Coord 3 RRG-2 ! Repeat for second well 1 3 15398 5377 -4845 15398 5377 0 15398 5377 1698 So create such a file named *.ctr and read it with File->Read Wells From File... Once loaded, expand the well list in the tree view and double click on any well to edit. You can then write the well data and it will create the TETRAD well !&# data files.
  14. Is there a way to enter TETRAD wells into PetraSim without entering them by hand?
  15. PetraSim grid boundaries can be based on a true coordinate system, they do not have to start at (0,0,0). You can define the boundaries to match the GIS coordinates, so that your model will use GIS coordinates. You cannot currently import a mesh that was created in another program.
  16. Is it possible to create a model based on GIS coordinates? If not, is it possible to use another mesh making program and using this as the input file for PetraSim?
  17. The absence of a boundary condition is "no flow".
  18. What type of boundary condition is used if the user does not assign a specific boundary condition to a bounding cell in a model?
  19. The absence of a boundary condition is "no flow".
  20. What type of boundary condition is used if the user does not assign a specific boundary condition to a bounding cell in a model?
  21. PetraSim requires a relatively fast CPU and a substantial amount of random-access memory (RAM). The processor should be at least as fast as a 1 GHz Pentium III, with at least 512 MB RAM. A fast graphics card that supports OpenGL 1.1 or later with 64 MB of graphics memory is recommended. Obviously, the larger your model, the more memory you are going to want to have. A lot of customers run very simple 1D or 2D problems using PetraSim. If you are running larger 2D or 3D models, I would recommend more RAM.
  22. What are the computing requirements for PetraSim in terms of processor speed and amount of memory? Are there any other computer issue for running PetraSim?
  23. The results options are not available because TOUGH-Fx uses a different output format that does not include the source/sink or connection data files.
  24. In the "Results" tab in PetraSim why is "Source/Sink Plots" and "Connection Plots" been deactivated?
  25. This options are not available for the TOUGH-Fx version of PetraSim. The Gravity-Capillary initial conditions option is only for the EOS9 module of TOUGH2.
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