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About Alison

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  1. I think that this error is probably related to the initial conditions you've specified. I believe that the fugacity coefficient is calculated by TOUGHREACT based on Pressure and Temperature. So, our first suggestion would be that you experiment with other CO2 partial pressures. Perhaps you should try a very small value, rather than a value of 0 for the cells with low partial pressure?
  2. Yes, for a constant Temperature boundary, you could use a very large density for the boundary cell.
  3. Alison


    I have been experimenting with your model and converted it to EOS3 so that I could add gas saturation to the model. I was able to see the pH in the cell change by doing the following: 1. Adding the gas phase to the model. For example, initialize the model with 0.2 SG, or even just the cell with the high gas zone. 2. Under TOUGHREACT | Solution parameters, make sure that NGAS1 is checked on.
  4. Atmospheric boundaries can be simulated by making the cells at the top of your model “fixed state” or by assigning them a very large volume factor. You would then want to assign appropriate initial conditions that would represent the atmosphere, and would also want to create a special material to assign to those cells. This can also be done using the “extra cell” tool in PetraSim. You would again assign a very large volume to the extra cell representing the atmosphere and create very short connections to the top layer of cells in the model. I would recommend that you take a look a that LBL TOUGH forum for some additional technical details about this. If you do a search in that forum for “Assigning atmospheric boundary conditions”, you should be able to access a PDF with additional instructions provided by Stefan Finsterle of Finsterle GeoConsulting. You can find information specifically discussing atmospheric boundaries starting around page 20. If you are not able to find this, please send me an email and I will direct to you to this document (alison @ rockware . com).
  5. If all of these variables do not need to vary, then the "Fixed State" option would work fine. If you need to vary the temperature or pressure of the boundary, then the very large volume option (either set to geometric cells or an extra cell) would be more appropriate. This way, you could add large amounts of water or heat to the cells to force fluctuations in temperature or pressure. There is a discussion of time-varying boundaries in the PetraSim manual.
  6. If you do a literature search for TOUGHREACT and Clay Swelling, a few articles do pop up on Google. Many of them seem to be by the TOUGHREACT authors at LBL, so you may want to contact them to see if they have any tips on how the simulated the swelling of the clay minerals.
  7. I think the answer to your question is yes, but you may need to provide an example to confirm. When viewing model results in 3D, there is an option to turn on isosurfaces. These basically connect points of equal pressure and temperature. PetraSim does not create 2D contour maps. If you need to create lines of equal pressure or temperature (say, from a slice of a model), you would probably want to export results to another program such as RockWorks, Surfer or TecPlot.
  8. We are not able to duplicate this problem with one of our files, so we would need to see your SIM file to determine what is going on. We also need to know which version of PetraSim you are running. Best Regards, Alison
  9. Unfortunately, aqueous complexes were not output in TOUGHREACT v1.2, which is the version of TOUGHREACT that is packaged with PetraSim. This feature was added in later versions of TOUGHREACT. You might consider purchasing TOUGHREACT v3.3, which is available through LBL. PetraSim creates input files for TOUGHREACT v3.3. We hope to add better support with result visualization in the future.
  10. It seems that there is not enough output to show the results. I would recommend the following: 1. For cells where you want to see a detailed time series plot, you should check on the Print options for the cells and rerun the model. This will output data for each time step to a FOFT file, that is then displayed here. You can do this by right clicking on the cell and choosing Edit Cells. 2. You could also increase the number of time steps being output for all cells. This is done through the Analysis|Output Controls menu. The default is to print every 100 time steps. You may need to decrease this to a smaller number.
  11. This is a fairly common message to see during a model run that is often resolved by the simulator with a time step decrease. If you see this error at the beginning of a model, and it is not resolved by a decrease in time step, then it typically indicates a problem with your initial conditions. If the error shows up in the middle of the model run and causes the simulation to halt, then it would indicate that the simulation has reached a state not supported, such as a very high or low pressure or temperature. If you are not sure what the problem is, you could turn on the print options for the problem cell, which would allow you to view time series data at each time step.
  12. The SIM file you provided does not run. It says that it is missing components related to the Co2 and H2S gases. I am not able to help you set up your geochemical model. However, I do see that the initial conditions for the extra cell in your model are set to single phase with an air mass fraction of 0. This would simulate single phase water conditions. If you change the air mass fraction to 1, it will simulate single phase gas conditions. You should try changing this to 1 if you are trying to inject gas using the Extra Cell.
  13. I think we would probably need to see your SIM file to comment on this. Could this have something to do with the initial phase state of the extra cell?
  14. Because you are seeing this error at the beginning of the model run, it looks like you have poorly defined initial conditions. I would suggest you look at the input file to get more information about the problem with data initialization. If a different phase is evolving, (for example, if the water phase is evolving in a single phase system), you should try increasing the air mass fraction. You could also switch to a 2 phase system with a very high gas saturation.
  15. A gas injection zone option is not available in TOUGHREACT v1.2, which is the version included with PetraSim (it is included in TOUGHREACT v3.3, which is available through LBL, but it is not supported in PetraSim). One way to get around this would be to attached an "extra cell" to the injection cell, which a very large volume and a short connection distance. You can assign a gas zone to that cell that represents the gas components you want to inject into the model, and assign a higher pressure to the cell. You can find more about Extra Cells in the PetraSim manual.
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