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Pressure drop using GENER

Dear Tough community,

I'm trying to run a 1D simulation with initial and boundary waters. I'm using GENER to drive the flow. The program runs, but I get a drop in pressure for each step in flowdata.tec. If I run the simulation for longer it crashes. I think the problem is that the pressure gets so low that the water starts to boil.

I don't understand why I get this drop in pressure because my injection and production rates are the same. Can anyone see a solution?

Cheers,

Eivind

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  • Eivind,

    It appears you're making this a non-isothermal simulation and introducing the fluids with zero empathy. If this isn't your intention, I'd suggest making the simulation isothermal, and at least allowing for the presence of a gas phase (even if it never shows up by the conditions of your simulation) by changing your MULTI block to 2 2 2 6.

    Thanks!

    - Mikey

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    • And shoutout to Stefan Finsterle, who pointed out a typo I wrote in my first response to this thread where I suggested the fluids were introduced with zero empathy (instead of enthalpy). I assure you this was, in no way, a moral judgement of the source term you created. : ) 

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  • Hi Mikey,

    Thanks for the reply. The simulations work now, but not as intended because the the drop in pressure is still there. The intention was to keep temperature, pressure and flow rate constant. Do you think the enthalpy is the problem?

    Cheers,

    Eivind

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    • Eivind, I think I was mistaken. You're running EOS1, I presume? Try 1 2 2 6 in the MULTI block.

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  • Yes, I'm running EOS1. I get a larger drop in pressure and also temperature with 1 2 2 6 in MULTI. I can get the temperature to be sort of stable with setting enthalpy = 1.0576E+5 , but I still have a drop in pressure.

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    • Eivind, the enthalpy will not matter if you run with an isothermal simulation, but it's good to keep in there anyway. I also forgot you'll need to change the TYPE from "WATE" to "MASS" on the production element A__19. I'm unsure if this will impact your results in any way, but, since you can't really control which components get produced from a sink term, you always use the "MASS" when producing flows (i.e., using a negative mass flow rate in GENER).

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    • I'd also suggest including initial conditions in record PARAM.4. These will get overwritten by what you include in INCON, but it's a good practice to put a default setting in there in case you miss any elements in your INCON/INDOM blocks.

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  • Thanks Mikey - Setting it to MASS didn't change the results. However, I think I found a solution to the problem. I removed the producer and changed the last cell to an infinite volume cell.

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  • Glad to hear it. I did notice your permeabilities were kinda high (~1.0E-12), and the volumes are small, so perhaps any small distinctions between injection and production rates would impact the simulation really quickly. This could be why the pressures in all elements (including the producer element!) dropped monotonically.

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