How to initialize reservoir pressure?

[wdmhouston]

Hi,

I find the following example code in CO2 injection example,

<FieldSpecification
  name="initialPressure"
  initialCondition="1"
  setNames="{ all }"
  objectPath="ElementRegions/Reservoir"
  fieldName="pressure"
  scale="1.25e7"/>

 Does this mean the initial pressure of each cell is 1x1.25e7 bar?

 Does GEOSX in current release support pressure from a GRDECL file (or other format), or specify an initial pressure at certain depth(automatically equilibrate for the whole model)?

Thanks and Regards,

wdm

[francoishamon]

Hello,
This means that the initial pressure is uniform, with a value in each cell equal to 1.25 x 10^7 Pa. All the pressure units that are in GEOSX (reservoir, wells) are in Pa.

Currently we do not support the PRESSURE input from the GRDECL file. Here is what you have to do to initialize the reservoir for pressure (and possibly for the other variables as well if you have, say, a gas-oil contact or something like that):

<FieldSpecification
      name="initialPressure"
      initialCondition="1"
      setNames="{ all }"
      objectPath="ElementRegions/Reservoir"
      fieldName="pressure"
      scale="1"
      functionName="initialPressureFunction"/>

    <FieldSpecification
      name="initialComposition_oil"
      initialCondition="1"
      setNames="{ all }"
      objectPath="ElementRegions/Reservoir"
      fieldName="globalCompFraction"
      component="0"
      scale="1.0"
      functionName="initialOilCompFunction"/>

    <FieldSpecification
      name="initialComposition_water"
      initialCondition="1"
      setNames="{ all }"
      objectPath="ElementRegions/Reservoir"
      fieldName="globalCompFraction"
      component="1"
      scale="1.0"
      functionName="initialWaterCompFunction"/>

and then in the Functions block of the xml file, you can do the following to initialize the pressure and the compositions, as a function of the position of the center of each cell:

<Functions>

    <TableFunction
      name="initialPressureFunction"
      inputVarNames="{elementCenter}"
      coordinateFiles="{xLin.geos,yLin.geos,zLin.geos}"
      voxelFile="pres.geos"
      interpolation="linear" />

    <TableFunction
      name="initialOilCompFunction"
      inputVarNames="{elementCenter}"
      coordinateFiles="{xLin.geos,yLin.geos,zLin.geos}"
      voxelFile="comp_o.geos"
      interpolation="linear" />

    <TableFunction
      name="initialWaterCompFunction"
      inputVarNames="{elementCenter}"
      coordinateFiles="{xLin.geos,yLin.geos,zLin.geos}"
      voxelFile="comp_w.geos"
      interpolation="linear" />
    
  </Functions>

If we take the example of the pressure above, you can use the pres.geos file to define the pressure at the locations given by the files xLin.geos, yLin.geos, and zLin.geos. Then, internally, GEOSX uses the center of each cell to interpolate in the table and assign a pressure value.

What you have to do is to compute externally the hydrostatic pressure, fill the pres.geos file with the hydrostatic pressure values, and fill the xLin.geos, yLin.geos, and zLin.geos with the coordinates of your reservoir. I attached example files (I had to remove the .geos extension to upload, you will have to put them back)
zLin.txt
yLin.txt
xLin.txt
comp_w.txt
comp_o.txt
pres.txt

We will start working on an internal initialization procedure, but it is not ready yet.