GENER BLOCK : water pumping EOS7r two phase problem
Hello everyone,
I want to pump water from a certain elements using EOS7R. I'm confused between using:
1. "COM1" as a type and a negative value of the rate (< 0) to mean that I extract water from this element.
or
2. Using "MASS" as a type of the general element, with a rate < 0 as described in the User's guide. I have a doubt about pumping also the gas phase when I consider only a "MASS" type.
Can anyone suggest the best use?
Thank you for your answers.
TOUGHLY,
9 replies
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for more specification : i want to pump componenet 1 (water) in liquid phase
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Hi,
TOUGH implements the physically accurate process that occurs during pumping: A suction is applied that produces a mixture of fluids, each consisting of multiple components. So the specified production rate must refer to the total mass (i.e., the sum of all components in all phases; type "MASS"). There is really no way to instruct a pump to only extract a certain component (e.g., water from the liquid phase), but leave all the dissolved air molecules behind, or only extract water molecules from the liquid phase, but ignore water molecules in the steam phase. Even if you have a phase separator installed (usually at the surface), the pressure response in the well is still governed by the phase distribution in the reservoir, which changes during production and is determined by the conditions in the reservoir. In short: it simply does not make physical sense to produce a specific component only!
Of course, it is easy to calculate (from the TOUGH output file) how much of the totally produced mass consists of liquid water molecules vs. water vapor vs. dissolved air vs. air molecules in the gas phase, but that is obviously different from actually selecting a component (or phase) in the sink term.
Conversely, during injection, you have to inject a component (not a phase; thus "COM1", "COM2", etc.), because the phase composition is automatically determined based on the thermodynamic conditions in the injection element (not by the pump!). You can inject multiple components (and their enthalpies or temperatures) into the same source element; which is the only thing you can control at the pump; it's phase composition is determined by the reservoir conditions.
I don't know what the details of your application are. I'm aware that for mimicking very special conditions (not those of a regular pump), you may actually want to specify a certain component or phase during production. Therefore, such an option has been implemented in iTOUGH2. However, I don't know whether this is available in TOUGH3. You can also try to control which phase enters the well element (i.e., simulating a membrane or filter through appropriate choices of relative permeability and/or capillary pressure functions), but this does not change the fundamental way TOUGH calculates production.
Good luck!
Stefan
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Unclear what you mean by "different results" (what different results compared to what alternative setting? Changing from positive to negative, or changing from MASS to COM1?). In iTOUGH2, if you set a negative rate, the type is automatically set to MASS. Keni will likely let you know what TOUGH-MP does.