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mixing fluids


rawls423
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Hi,

 

I realize there is a tutorial on the GWB website and information about mixing two fluids in the different manuals, but after reading those instructions I'm still having trouble.

 

My steps are:

Input fluid #1 in react

Run

Run>Pickup>System>Entire/fluid (I've tried both)

 

when I go back to the basis pane to input fluid #2, the basis pane is populated by the results of fluid #1. I assumed it didn't matter and proceeded as follows:

 

input fluid #2

config>stepping>flash>fluid/system (I've tried both)

Run

 

When I try to plot anything in gtplot, there is only 1 data point, not a line spanning the entire reaction progress. The results from this are very similar from when I just input fluid #2 and then Run.

 

Any help would be appreciated.

 

Thank you

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Hi,

 

The problem is that you've chosen Run > Pickup > System instead of Run > Pickup > Reactants. When you choose System your calculation results are sent back to the Basis pane (think of this as the initial system). This may seem like a strange thing to do, but here's an example. You might use a sliding temperature path to heat up a sample, pick up the calculation results and send it back to the Basis pane, then titrate some minerals into it.

 

To mix fluids, however, you should choose Reactants so that your first fluid is sent to the Reactants pane. When you do this, the Basis pane is vacated and you're free to specify the composition of your second fluid. The first fluid you specified (the reactant) will then be mixed into the second fluid.

 

I'm glad you found our Tutorials page. FYI, we added a new fluid mixing page to our website with the launch of GWB10.

 

Regards,

 

Brian Farrell

Geochemist

Aqueous Solutions LLC

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Hi,

 

I've been able to mix the fluids now. Another question just to make sure I understand what I'm seeing.

 

When I plot pH v Rxn progress for a mix, which end of the spectrum represents fluid #1 (the fluid i 'picked up') 0 or 1? And as GWB titrates in the 'picked up' fluid, it gets rid of some of fluid #2, correct? So that when Rxn progress = 0.5 that means there are equal parts fluid #1 and fluid #2/

 

Thank you

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Also, what exactly am I picking up when I pickup (Run-Pickup-System-Fluid) the results of a mix?

 

Can I indicate that I'd like to pick up the results of a 1:1 (or any ratio) mixture?

 

What I'm trying to do is heat up a sample (fluid#1) to reservoir temperature, mix it with the brine (fluid #2) at reservoir temperature and then cool down the water to simulate movement to the surface. Because I only know the brine composition at the surface, in another React window I've heated the brine to reservoir conditions and then manually entered the results as fluid #2 for the mixing.

I hope that's understandable.

 

Thanks

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Hi,

 

I've been able to mix the fluids now. Another question just to make sure I understand what I'm seeing.

 

When I plot pH v Rxn progress for a mix, which end of the spectrum represents fluid #1 (the fluid i 'picked up') 0 or 1? And as GWB titrates in the 'picked up' fluid, it gets rid of some of fluid #2, correct? So that when Rxn progress = 0.5 that means there are equal parts fluid #1 and fluid #2/

 

Thank you

 

Hi,

 

Rxn progress of 0 corresponds to the initial step of your most recent calculation, while Rxn progress of 1 represents the final step. So, if you take fluid #1, equilibrate it (Run-Go), pick it up and make it a reactant (Run-Pickup-Reactants-Fluid), then define a new fluid, Fluid #2, in the Basis pane, once you perform the mixing (Run-Go) Fluid #2 will correspond to Rxn progress of 0, since that's the initial system. The reactant is gradually titrated into the initial system (by default this titration occurs in 100 steps). In your example, you start with Fluid #2, add 1/100th of the mass of Fluid #1, then another 1/100th, and so on, until 100% of the mass of Fluid #1 has been added.

 

By default, GWB does not get rid of the contents of the Basis pane (fluid #2) as it titrates in the contents of the Reactants pane (fluid #1). So, if each fluid is 1 kg solvent (plus some solutes), you should see the solution mass increase from ~1 kg to ~1.5 kg to ~2 kg as you move from Rxn progress of 0 to 0.5 to 1.

 

Fluid #2 is only gradually removed if you select the "Flash" option in the Config - Stepping menu. This is done to create a "Flash diagram", which is more of a tool for understanding what could happen as two fluid mix then a simulation of an actual mixing process.

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Also, what exactly am I picking up when I pickup (Run-Pickup-System-Fluid) the results of a mix?

 

Can I indicate that I'd like to pick up the results of a 1:1 (or any ratio) mixture?

 

What I'm trying to do is heat up a sample (fluid#1) to reservoir temperature, mix it with the brine (fluid #2) at reservoir temperature and then cool down the water to simulate movement to the surface. Because I only know the brine composition at the surface, in another React window I've heated the brine to reservoir conditions and then manually entered the results as fluid #2 for the mixing.

I hope that's understandable.

 

Thanks

 

When you do a Run-Pickup-System-Fluid, you are picking up the fluid (but not any minerals) that are the result of whatever calculation you've specified. So, if you've just started by defining a single fluid (1 kg solvent plus solutes) then do Run-Pickup-System-Fluid you'll end up with the same fluid in the Basis pane, minus any minerals that might have been present. If you had mixed two fluids (each 1 kg solvent plus solutes) then you would end up with ~2 kg fluid at the end of your mixing simulation, and if you do Run-Pickup-System-Fluid you'll end up with ~ 2 kg in the Basis pane.

 

Taking a step back, if you look at the Reactants pane, you'll notice a box labeled "Reactants times" which is by default 1. This number is a multiplier (default 1) for the contents of the Reactants pane to be titrated into the Basis pane (which defaults to 1 kg solvent plus the mass of solutes). So if you have your Fluid #1 in the Reactants pane and leave "Reactants times" at 1, then specify Fluid #2 in the Basis pane, you'll end up with ~ 2kg fluid after mixing. If you set "Reactants times" to 2, you'll be adding ~2 kg of Fluid #1 to ~1 kg of Fluid #2, for a total of ~ 3 kg fluid in the mixture. Set "Reactants times" to 0.5 and you'll end up with ~1.5 kg in the mixture.

 

As an alternative, you can change the mass of solvent in the Basis pane from its default of 1 kg.

 

Moving on to the problem you described, if I understand correctly, you might follow these steps:

 

1) Open React, specify the composition of your sample (Fuid #1), and set an initial (room) and final (reservoir) temperature. This is called a polythermal path. Do Run-Go to trace the path, then do Run-Pickup-Reactants-Fluid so that the sample is now a reactant.

 

2) Open a second window of React, specify the composition of your brine (Fluid #2), and set an initial (room) and final (reservoir) temperature. Once again, trace the polythermal path by doing Run-Go, then do Run-Pickup-Initial-Fluid to move the heated brine fluid to the Initial system.

 

3) You now have two windows of React open, one with the heated sample as a reactant (Reactants pane), the second with the heated brine as the Initial system (Basis pane). If you have GWB9 or 10, you can drag the heated brine into the Basis pane of the first React window (right-click and hold the Basis pane label and drag it into the other Basis pane). If not, I would save the heated brine (File - Save as), calling it HeatedBrine.rea. Go back to the first window of React and do File - Open - Read script and browse to find HeatedBrine.rea. Be sure to say no to resetting the configuration. Now, you should have the heated brine in the Basis pane and the heated sample in the Reactants pane. Set a value for "reactants time" if you want, then do Run-Go to mix the fluids.

 

4) Do Run-Pickup-Initial-Fluid to move the mixed sample to the Basis pane and clearing the Reactants pane. Your initial temperature should be the reservoir temperature. Set a final temp to simulate cooling, then do Run-Go.

 

Hope this helps,

 

Brian Farrell

Geochemist

Aqueous Solutions LLC

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