GENER : COM1 vs MASS type ---->Pumping water from element in a 2phase flow 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.


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.


water means the component one but the simulation can tolerate pumping also the disolved component 2  in the liquid.  The main goal is to pump only liquid phase in component 1 (water)

Can anyone suggest the best use?

Thank you for your answers.


2 replies

    • Staff Scientist
    • Christine_Doughty
    • 2 wk ago
    • Reported - view

    For pumping from a certain element, it is better to use MASS with a rate <0.  Here is what the TOUGH2 Users Guide says about controlling the phase that you pump out:

    MOP(9) determines the composition of produced fluid with the MASS option
    (see GENER, below). The relative amounts of phases are determined as follows:
    0: according to relative mobilities in the source element.
    1: produced source fluid has the same phase composition as the producing element.

    Either of these is a physically reasonable choice.  If you don't want gas to come out, make sure it has zero mobility in the producing element and use MOP(9)=0 (the default).  You can get zero mobility by setting residual gas saturation to a value larger than the gas saturation in your producing element.

    In my experience, under normal conditions, you should not specify a single component to pump out, as it wouldn't be physically reasonable.  The things that respond to pressure gradients or pumping are phases, not individual components.  You could imagine having some kind of special filter that would only let out certain components, but that is not what I consider normal conditions.

    Best wishes, Christine

    • woemn_geoscience
    • 2 wk ago
    • Reported - view

    Thank you Christine for your help 👋

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