Figure 3: TOUGH2 model with an unstructured grid 2
By Seequent Product Director of Energy, Brennan Williams

Based on the feedback from our current Leapfrog Geothermal users over the last 12 months, we have been working to advance the workflow between the conceptual geological model and the numeric flow model in Leapfrog Geothermal.

With the release of Leapfrog Geothermal 3.6, a TOUGH2 flow model with an unstructured grid can now be created, on to which the geological model rock types and also fault rock types are evaluated. The TOUGH2 model can then be exported and run in the flow simulator.

Geological model with faults and wells
Figure 1: Geological model with faults and wells

TOUGH2 model with an unstructured grid
Figure 2: TOUGH2 model with an unstructured grid and rock type evaluation; faults not included as gridding features

The unstructured grid is a Voronoi grid in X, Y and layered in Z. An internal algorithm, based on Delaunay triangulation, is used to construct the grid, taking into account:

  • the boundary
  • an approximate default grid block size
  • the number of layers and layer spacing
  • a list of features such as well locations/perforations and faults to guide the gridding
  • gridding control options for grid simplification and feature snapping

The TOUGH2 model is created using an associated conceptual geological model and the link between these two models is dynamic, so your model stays up to date, throughout the life cycle of your project. Any changes to the geological model due to new data or new interpretation of existing data will cause the TOUGH2 model to be dynamically updated, including the grid geometry and the evaluation of the rock types, both of which are dependent on the geological model and faults.

Figure 3: TOUGH2 model with an unstructured grid 2
Figure 3: TOUGH2 model with an unstructured grid and rock type evaluation; faults included as gridding features

And there is flexibility in the workflow. For example, if the subsurface team do not want the TOUGH2 grid to be updated, only the rock type evaluation, then a static copy of the TOUGH2 model can be made; this makes the grid definition static while still allowing the rock type evaluation to be updated and exported.

To complete the workflow, time dependent data, output by a TOUGH2 simulation run, can be imported from a LISTING file and visualised in the 3D scene.

For more information on the new TOUGH2, and all other features in Leapfrog Geothermal 3.6, click here.