Prescribed boundary conditions for chemistry but constant flow rate BCs for flow
Hi all,
I'm using TOUGHREACT with ECO2N module. In the simulations, the flow is injected at a constant flow rate and due to dissolution/precipitation, the pressure would change at the boundary cell. However, the injecting fluid composition is set to be the same throughout. If I make a large cell at the injecting boundary, then everything will be fixed including pressure; but if I let pressure change then the fluid chemical composition will also change. How do I solve this problem.
Thanks a lot,
Luanjing
4 replies
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If you set an injection boundary (prescribed flow rate), the pressure may change if permeability changes with reaction, but the injection composition should remain constant if the injection composition is defined using the "boundary water" inputs. The injection composition is entered in chemical.inp as a "boundary water", which must be listed after the initial water composition(s); also make sure that the number of "boundary waters" is set to 1. The assignment of boundary waters to specific grid blocks is then done in file solute.inp. The flow rate is specified in the GENER file (or GENER input block in flow.inp). Make sure you use the same gridblock names in the GENER and solute.inp file (for the injection gridblocks). I hope this answers your question.
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Nic,
Thanks for your answer. What you suggested is what I did in the input files. I also tried to assign the boundary water to only the injection cell in the
Record_15.!!Chemical!property!zone!indices!for!specific!grid!blocks
of solute.inp.
I checked out some of the example files involving mineral reactions, and I saw the changes of chemical composition in the injection cells as well. I think the reason is that there's only 1 mineral zone and it covers the whole domain including the injection cell. So as the reactions take place, the chemistry changes. Should I make another mineral zone for the "nonreactive" injection cell?
Thanks a lot,
Luanjing
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Yes, this is typically how it is done. Specify zero surface area for each mineral in the non-reactive mineral zone, and/or IKIN=2 (after the initial volume entry) to make each mineral unreactive.
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Nic,
That solved the problem. Thanks a lot.