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dirk

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  1. Hi Karen, I have put together scripts for a wide range of minerals mostly based on the Palandri and Kharaka paper. Dissolution is TST and precipitation is nucleation and crystal growth based on Helge Hellevang's work. Let me know if you want to try them out. Cheers Dirk
  2. Hi Jia, thanks for the advice! I am using custom rate law scripts with transition state theory dissolution and nucleation and crystal growth terms for precipitation that I can easily change by throwing a scalar in. It seems to work in most cases but i do run into some convergence problems but I have not yet put the scalar in so that might get me through. The models are in X1t as cation exchange is important and we are trying to simulate what is happening in the columns so that we can upscale to field sites.
  3. I have some column experiments where, based on the evolving water chemistry, some minerals are precipitating essentially at equilibrium (as calcite dissolves). Later in the experiment those same minerals dissolve but not at equilibrium, rather at a rate that I hope to match with a 1D flow through model. Is it possible to set precipitation at equilibrium and assign a rate for dissolution?
  4. Hi Jia. Thanks for the quick response. Yes, the calculation works but I need to know how porosity is impacted and the entire change in quartz for instance is due to the increase in the bulk volume which is due to an increase in the fluid volume (density increase) not to the mineral volume. In the subsurface the result would be a pressure increase and either fluid flow or fracturing, but without fracturing the the volume% change would reflect the porosity change where in this case it does not. Is there a way to set this up so that the bulk volume stays the same? See column J in the spreadsheet.delta vol calc.xlsx Dirk delta vol calc.xlsx
  5. Hi, I noticed that for my plots of a reaction path model there was a large difference between the delta cm3 and the delta vol%. I expected that the delta vol% would equate with the change in cm3 of a mineral to the total vol of minerals but that cannot be the case. Can you explain to me what I am looking at in the vol% plot? Cheers Dirk
  6. Hi Jia, it 12.0.7 GWB Professional. I have attached the plot file and thermo database (I think this is needed for the plot?). I can open it on my other computer no problem so am wondering if it is not something I can fix by re-installing? I did not include the React input file because it uses a modified thermo database and a bunch of script files for kinetics based reactions and that just ends up being too much information... React_plot.gtp thermo.com.V8.R6+CO2SO2.txt
  7. Hi, not sure if anyone else is suffering from this but Gtplot and Xtplot crash when starting up from within React and X1t. The plot files are not always very big and it seems to be fine after a re-boot for a while but usually on the 2nd run of GWB programs post re-boot the plot programs crash when I try to plot anything, even previously plotted files.
  8. Hi, I am trying to calculate mineral saturation indices from GSS with the YMP thermodynamic database. The calculation fails because the speciation cannot be completed with the following error. Ionic strength out of range. Largest residual(s): Resid Resid/Totmol Cbasis Al+++ 2.247e+06 1 4.256e-07 If I run the same in SpecE8 it gives a similar result until I change the Al from Al+++ swapped to AlO2-, then it works. It also works if there is a lower concentration of Al+++. I understand that I am entering a component amount so I am not sure why there would be an error since it is just the total Al for the system. Anyway, attached is the GSS (this just has one water but my sample set is much larger and I would like to be able to plot saturation indices).
  9. Hi, I am trying to calculate mineral saturation indices from GSS with the YMP thermodynamic database. The calculation fails because the speciation cannot be completed with the following error. Ionic strength out of range. Largest residual(s): Resid Resid/Totmol Cbasis Al+++ 2.247e+06 1 4.256e-07 If I run the same in SpecE8 it gives a similar result until I change the Al from Al+++ swapped to AlO2-, then it works. It also works if there is a lower concentration of Al+++. I understand that I am entering a component amount so I am not sure why there would be an error since it is just the total Al for the system. Anyway, attached is the GSS (this just has one water but my sample set is much larger and I would like to be able to plot saturation indices). Test ymg 25.gss
  10. Thanks Jia, decided to do the old fashioned thing of just a restart, that worked.
  11. Hi, Xtplot keeps crashing when I try to plot a model that I just ran, doesn't matter how you try to start it, from the Run Complete window, from the file folder or from the GWB start up. Anyone else have this problem? It is a largish file, 19.5 Mb but that should not be a problem I would think. Even plots files that I could previously view do not open.
  12. Hi, I am trying to model some batch reactor experiments. Set up using kinetics scripts for the reactions but also want to include adsorption. The problem is how to set up so that there is an initial adsorbed composition that is in equilibrium with the local groundwater. In the experiments we take the sediments collected from core and add some contaminated water and monitor the reaction progress to provide data for history matching using the model. This then helps get what reactions are happening and rates. There are adsorption sites present and they are occupied so have an impact on the water composition as they desorb and new adsorption composition establishes during the batch run. I am not sure how to set this up using React. I can run it in PHREEQC since you are able to assign a adsorption composition using SURFACE. Any ideas would be great!
  13. Ok, sorted some out. Turns out the contaminated fluid was undersaturated with respect to Fe(OH)3 so by day 8 it has exhausted the Fe(OH)3 and that made convergence not possible for some reason that seems to be related to increase in the length of the reaction step in the first cell. So using goethite instead, seems to be working.... So I am wondering about the why of it. Fe(OH)3 is the adsorbant and is the breakdown because there is no adsorbant left , other minerals (calcite for instance) do go to 0 in the first cell, so does that mean that there has to be some adsorbant left in a cell in order for simulation to go forward?
  14. Sorry posted this on the archive thread... Hi, I am running a simulation of a flow through column experiment and slowly working up to the full rtm. I run the initial solution through for 5 days then the contaminated solution. calcite reacts based on kinetic constraints, precipitation of gypsum, gibbsite, Fe(OH)3 at equilibrium all else suppressed, adsorption using the D&M model and the FeOH database (decreased site densities of w and s sites by an order of magnitude). after adding adsorption I cannot get it to finish. current error is "Step is constrained by rate of increase in length of reaction step at node 0." after 8 days of 10 day run. Any ideas? Dirk
  15. Hi, I am running a simulation of a flow through column experiment and slowly working up to the full rtm. I run the initial solution through for 5 days then the contaminated solution. calcite reacts based on kinetic constraints, precipitation of gypsum, gibbsite, Fe(OH)3 at equilibrium all else suppressed, adsorption using the D&M model and the FeOH database (decreased site densities of w and s sites by an order of magnitude). after adding adsorption I cannot get it to finish. current error is "Step is constrained by rate of increase in length of reaction step at node 0." after 8 days of 10 day run. Any ideas? Dirk
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