Creating a 3D sub-grid

You can create a smaller or rotated 3D grid based on an existing 3D grid and map the properties of the existing grid onto the new grid. This can be useful for assessing the simulation requirements and constraints for restricted areas of an existing (structured) grid, especially for hydraulic fracture modeling, where you can investigate several well and fracture configurations to determine optimal flow performance.

An organized and easy way to create such a sub-grid is the Sub-Grid tool (Model > 3D Grid > Grid from Grid > Sub-Grid).

To create a 3D sub-grid

  1. Open the Sub-Grid tool and, under Select regional grid, select the 3D grid you want to create the sub-grid from. The new grid will be a subset of this regional grid.
  2. Under Select or specify a new grid, select New and specify a name for the new sub-grid in the Name field, or select an existing grid that you want update or edit.
  3. Under Select area, set the area for the new grid. Select an existing area, or to specify a new grid area, click the Edit button. The Area tool appears. For details on how to use this, see Area tool.
  4. To include and honor the regional grid faults in the sub-grid, check the Use faults check box. If you do not do this, the traces of the regional faults are smoothed over.
  5. In the Create grid step, check the Generate geometry properties check box to generate the following default set of geometrical properties for each grid cell in the sub-grid; Cell Top Depth, Cell Volume, I (index indicator), J (index indicator), Stratigraphic Cell Thickness and Cell Top Depth.
  6. To create the sub-grid, click Create.
  7. Under Map properties, check the checkboxes next to the grid properties that you want to map onto the sub-grid.

  8. Check the Interpolate mapped properties checkbox to populate the sub-grid cells with an interpolated property value from surrounding source grid cells (using the linear least square interpolation method). If you leave this unchecked, the sub-grid cells are given the property value of the source grid cell in which their cell center occurs.

    If you check the Use prefix checkbox and enter a prefix in the field to the right, the name of the output property becomes: <Specified prefix>_<(optional specification)><property name>. The Default prefix is ‘Mapped’. If you check the Use suffix checkbox and enter a suffix, the name of the output property becomes: <property name><(optional specification)>_<Specified suffix>. The default suffix is ‘Mapped’.

    If the Replace all values checkbox is checked and a property with the same name already exists it will be overwritten. If you create a property with an existing name and you do not check Replace all values, the new property is added with a sequential number added to its name.

    If Replace only with valid values is checked and a property with the same name already exists, only cells with valid values will be replaced.

  9. To perform the property mapping, click Map properties and then click OK to close the form.