Providing a reservoir description

On the Reservoir Description form you specify the porosity model to be used in the simulation, connect the properties from the associated 3D grid, and specify the parameters to create a simulation grid from a JewelGrid, if applicable. You can also specify the grid properties by opening the Reservoir Description view from the Reservoir Description form.

To select the porosity model and reservoir properties:

1. Select the porosity model to be used in the reservoir simulation. Five options are available:

   • Single porosity
   • Dual porosity (DUALPOR)
   • Dual permeability (DUALPERM)
   • Multiple Interacting continua (MINC)
   • Subdomain (SUBDOMAIN)
   Important  To use the Fault Seal Model or a Zone to Zone Transmissibility Multiplier Model in combination with different porosity systems, make sure you are using CMG's 2022.30 release version or newer.
   You cannot perform this step if the grid specified on the Create Case form is not a JewelGrid.

2. Optionally, and in the case that the associated 3D grid is a JewelGrid, you can define how the application creates the simulation grid. The why and how of the creation of a simulation grid (including the checkbox options as provided on the form and listed below) are described in more detail in Reservoir simulation using a JewelGrid.

   Include impenetrable layers  Select this option if impenetrable layers must be included.

   Merge multiple IJK cells  If this option is selected, the application will try to merge multiple IJK cells with neighboring cells. This reduces the number of multiple IJK cells and hence the need to re-allocate cells in the simulation grid. If all multiple IJK cells can be merged, no additional layers need to be created in the simulation grid.

   Merge small cells  All simulators have the option to exclude small cells. Inactive cells do not contribute to the total volume of the system, and are treated as a barrier. However, the Merge small cells option does not just make small cells inactive, but adds the volume of the merged small cells to a bigger neighboring cell in the same layer and reallocates the connections of the merged cell to the cell in which it is merged. Hence, both total volume of the system is maintained and no barriers are created. When using this option, you will not lose any connectivity.

   The Fraction of average cell pore volume in same layer value is used to categorize cells as small. Example: if the value is set at 20%, a cell with a pore volume less than 20% of the average cell pore volume in the same layer is considered as small.

   Another way to define small is by specifying a Minimum pore volume. A cell with a pore volume below the minimum is merged.

   If a cell meets either one of the criteria, it is merged.

   Carefully consider whether there are small cells that you do not want to be merged, and set up the two criteria accordingly. For example, if you want to retain certain small cells, for instance in a thin layer that is important for flow, you should set a very low value for Minimum pore volume.

   Merge pinch-out cells  Any simulator has the option to exclude pinch-out cells. This means that the simulator will automatically generate non-neighbor connections between the active cells on either side of the pinched-out layer(s), allowing fluid to flow across it. Generally, the layer or layers of inactive cells are deemed to be pinched-out if their overall cell thickness is less than the specified threshold value.

   Minimum cell thickness: specify the minimum cell thickness. Cells with smaller thickness are merged.

   The difference between the Merge small cells option and the Merge pinch-out cells option is that the former uses relative cell volume as a criterion while the latter uses actual cell thickness.

   The 'Merge small cells' and 'Merge pinch-out cells' options are 'or/or' options; as soon as one of the criteria is matched, a cell is merged to a bigger cell in the same layer.
   Important  Cell center calculations have been improved in JewelSuite Subsurface Modeling 2022.3. These improvements will also be applied while using one of the options to merge cells in the simulation 3D grid.

3. Click the Edit reservoir button to open the Reservoir Description view for the active simulation case.

   Filter source by property type  When this option is checked, the available sources for each property in the Reservoir Description view are filtered by property type. For example, if you want to select the source for the Reservoir Property 'Porosity', the list that you can open in the 'Source' column will only contain properties with type 'Porosity'. This is a useful option when working with grids with many sources, as it reduces the time it takes to search for the appropriate source and eliminates the possibility of inadvertently selecting a non-matching source.

4. If you wish to automatically populate the source properties, click the Connect properties button. The Reservoir Properties tab in the Reservoir Description view is automatically filled with properties from the 3D grid that you have selected in the foregoing Simulation Case form. The automatic selection is based on the property name. In the 'Source' column of the Reservoir Properties tab in the Reservoir Description view, the relevant grid properties appear. The 'Source' column can only be filled automatically if, for a certain reservoir property, the 3D grid only contains one source property.

   Connect properties  Updates the source column in the property table in the Reservoir Description view. The option is disabled if no grid is selected for the simulation case in the Simulation Case form.

5. Optionally, you can create a schematic grid by clicking the Create schematic grid button. A valid case and starting date must be selected in the Simulation Case form to create the schematic grid. The schematic grid is created as a new 3D Grid under the 3D Grids item in the JewelExplorer, with the name convention <simulation case name>_schematic. The schematic grid is for QC purposes only and should not be used to run a simulation case. For more on how schematic grids are used in simulation, see Creating a simulation grid.