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Coralie

X1t; how to set up Initial Fluids and Reactants

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Hi,

I am trying to model the flow of a brine into a basalt using x1t.

I have read the documentations in React and x1t but must be doing something wrong.

I thought I had to enter all the elements in Initial as well as Fluids tab.

In the Initial, I added the fluid composition and the mineralogy of the basalt the fluid will flow through.

In the fluid pane I copied the initial pane, but unswap the mineralogy and reduced their concentration as I only want the fluid composition here.

In the reactants pane I added the composition of the basalt as oxide (wt%).

Well not surprisingly, it doesn't converge. When I look at the command pane, I have many "???' for values I added for the minerals, and also for the fluid composition. Why is that?

Do I need to equilibrate the fluid and the rock in the initial pane first in react then import the results?

Any help with setting this up would be much appreciated.

Attached is the file.

Kind regards

Coralie

Tholeiitic-basalt-simple-brine.x1t

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Hi Coralie,

Do the minerals swapped into the Initial system represent the complete mineralogy of the basalt? Are they all in equilibrium with the initial porewater? Usually you include minerals in equilibrium with the porewater in the Initial pane. Minerals that are present but not in equilibrium can be set with kinetic rate laws on the Reactants pane. Then the infiltrating boundary fluids can react with those equilibrium and kinetic minerals. Adding the oxide components of the rock as simple reactants, as you've done, is much less common. And if you're just duplicating the composition of rocks in the Initial pane, you probably don't need to do it.

I'm not sure what you mean with the ??? for minerals. I don't see that in your script anywhere. 

If you'd like to work on this script a little more and have someone take another look, please attach your custom thermo dataset as well.

Regards,

Brian Farrell
Aqueous Solutions LLC

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Hi Brian,

Thank you for this. It helps.

I have now removed the reactants and tried several runs modifying the Initial (volume % of mineralogies relative to fluid, thus porosity, fluid composition, charge balance), but none of them are converging.

The residual is, if I understand properly, too high for Na+. I tried the charge balance on Na and K instead of Cl. But I'm having the same issue.

I manage to do the model with react though. So I am not sure what I am not doing right in x1t.

I attached both the x1t and react scripts.

I have changed the thermodynamic dataset so that it won't be an issue for you to open.

In the initial pane, I entered a simple fluid composition and host-rock composition (basalt). Do I need to run react first to get those two at equilibrium and use the results in the initial pane of x1t?  Just like I would have to do it for a flush model in react, using the "pick up" command? For the sake of simplicity here, I am assuming the mineralogy is in equilibrium with the fluid, and I am not using kinetic reactants.

Any help would be much appreciated

Regards

Coralie

Tholeiitic-basalt-simple-brine-2.x1t

Simple-fluid-tholeiitic-basalt.rea

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