Can We Change the Scale in Basin Modeling with Local Grid Refinement?

Thibaut, Muriel, Yannick Caillabet, Eric Flauraud, Frederic Schneider, Institut Francais du Petrole, Rueil-Malmaison Cedex, France

In reservoir characterization, Local Grid Refinement is applied routinely on unstructured grids for fluid flow simulation. In basin modelling, LGR has been recently implemented. Basin models require different and oftentimes more complex numerical treatment of physi­cal phenomena than reservoir models.

Large numbers of cells are not feasible for basin simulators, because of excessive pro­cessing time. The number must be reduced by averaging properties in such a way that flow and geological characteristics are retained. LGR changes substantially the number of cells, allows to treat two or more imbricated Cartesian grids refining in all three spatial directions with several levels of refinement but the regridding is done with the intent of preserving small features generated in a reservoir simulation, or of recording events at small scales. The flow simulator takes into account the entire model with local refined areas.

LGR is used to add details where justified by data availability and to keep a coarse res­olution where less data are available.

Results of the methodology are presented on a real case study. This is particular demon­strating for pressure simulations, where processing times are cut significantly without loss of good results.

As a conclusion, LGR is a solution for the coupled approach between basin and reser­voir scale. Improving the computer performance and increasing the 3D geometry precision, continuously, will aid to share a common Earth model between basin modelers, drillers, and reservoir engineers.