GAS-WATER: flow condition to initialize a study with constant pressure and saturationsΒΆ

In the Gas-Water model there are three possible states in any region:

  1. Undersaturated water: only the aqueous phase is present.

  2. Undersaturated gas: Vapour phase only present.

  3. Saturated: both phases are present.

For a region in the undersaturated water state, you must specify the pressure of the aqueous phase, and the mole fraction concentration of the dissolved gas as in the following example:

FLOW_CONDITION initial
  TYPE
    LIQUID_PRESSURE dirichlet
    GAS_IN_LIQUID_MOLE_FRACTION dirichlet
    TEMPERATURE dirichlet
  END
  LIQUID_PRESSURE 1.20D7 Pa
  GAS_IN_LIQUID_MOLE_FRACTION 1.D-6
  TEMPERATURE 45.0d0 C
END

Note that the mole fraction does not include the salt in the brine - this will be moles of CO2/ (moles of water+moles of CO2)

For a region in the unsaturated vapour state, you must specify the pressure of the vapour phase, and the mole fraction concentration of the water vapour as in the following example:

FLOW_CONDITION initial
  TYPE
    GAS_PRESSURE dirichlet
    WATER_IN_VAPOR_MOLE_FRACTION dirichlet
    TEMPERATURE dirichlet
  END
  GAS_PRESSURE 1.20D7 Pa
  WATER_IN_VAPOR_MOLE_FRACTION 1.D-5
  TEMPERATURE 45.0d0 C
END

For a region in the saturated state, you must specify the pressure of the aqueous phase, and the saturation of the gas phase as in the following example:

FLOW_CONDITION initial
  TYPE
    LIQUID_PRESSURE dirichlet
    GAS_SATURATION dirichlet
    TEMPERATURE dirichlet
  END
  LIQUID_PRESSURE 1.20D7 Pa
  GAS_SATURATION 0.5
  TEMPERATURE 50.0 C
END