Preserving Geological Information during Real-Time Editing of Faults in Tetrahedral Models
Résumé
Modelling underground physical processes with finite elements or finite
differences methods requires volume meshes of the subsurface. Tetrahedral grids offer much
greater geometric accuracy than Cartesian or curvilinear grids because cell sizes and shapes
can adapt to complex geological features. In tetrahedral grids, faults can be modelled as
topological discontinuities. Accounting for new information on fault geometry through a
complete rebuild of the model is time-consuming. Instead, we present a tool which makes
small geometric modifications to faults in tetrahedral models. Fault editing is performed
without computing a new tessellation for the whole model, and in real-time so that feedback is
immediate. If these modifications occur close to a fault contact, consistent fault contact
geometry is maintained: the secondary fault moves along the main fault without going
through it, and the overall shape of the main fault does not change. When the edited model
contains geological properties, the rock properties attached to the points in the model are
updated in order to maintain the spatial continuity of the property in each fault block and
according to fault throw, and to maintain the conditioning to well or seismic data in the edited
domain.