Doc v4.20.01 - © KAPPA 1988-2011
Guided Session #6: Compositional Thermal Option
• Rub
GS06 - 8/22
For simplicity we are going to keep a uniform description of the rock properties. So keep all
properties to their default values. We still need to specify the geothermal profile, so click on
the geothermal gradient button
and set a constant geothermal gradient as below:
Fig. C01.12 • Geothermal gradient definition
Note that the geothermal profile could have been alternatively defined by unchecking the
‘constant gradient’ box and allowed for a geothermal profile with varying gradient.
Click now on ‘OK’ to validate the constant gradient geothermal profile.
We now need to initialize the fluid column. To proceed click on the initial state button ,
the initial state definition dialog appears.
In this multiphase context we need to specify the depth of the Water-Oil Contact (WOC) and
the depth of the Gas-Oil Contact (GOC) as well as a ‘Reference Initial Pressure’ at a ‘Reference
Depth’ in the initial fluid column.
If a GOC is defined with its reference pressure point, Rubis will derive the mixture composition
of the corresponding fluid such that the gas-cap and the underlying saturated oil are in
equilibrium at the contact (see illustration on figure C01.13).
From the GOC, phase compositions are adjusted to ensure thermodynamic equilibrium in the
initial fluid column (the saturation pressure is adjusted with a hydrostatic correction and the
corresponding compositions are derived in an iterative process).
The resulting initial fluid column, with varying phase compositions, is in hydrostatic equilibrium
(see figure C01.16
for illustration on varying phase compositions).
Note:
9
Rubis allows the user to alternatively define the saturation pressure profile (in the
‘Saturation pressure’ tab), in this case it adjusts the fluid compositions accordingly in
the column.
9
In order for the equilibrium condition at the GOC to be possibly met, one must ensure
that the chosen ‘Reference Initial Pressure’ at the corresponding reservoir temperature
lies
within the critical point loci
of all possible mixture of the chosen components.
1...,422,423,424,425,426,427,428,429,430,431 433,434,435,436,437,438,439,440,441,442,...485