Automatic correction and simplification of geological maps and cross-sections for numerical simulations

in: 2018 Ring Meeting, ASGA

Abstract

Incorporating prior geological knowledge in geophysical process models often meets practical meshing challenges and raises the question of how much detail is to be included in the geometric model. We introduce a strategy to automatically repair and simplify geological maps and geological cross-sections and the associated meshes while preserving elementary consistency rules. To identify features breaking validity and/or the thin features potentially problematic when generating a mesh, we associate an exclusion zone to each model feature (horizon, fault). When these zones overlap, both the connectivity and the geometry of the geological layers are automatically modified. The output model enforces specific practical quality criteria on the model topology and geometry, that facilitates the generation of a good mesh, i.e. minimum angles and minimum local entity sizes. Our strategy is demonstrated on an input invalid geological 2D cross-section from a real case study model in the Lorraine coal basin. We further explore the impacts of the model modifications on wave propagation simulation results. We show that the differences on the seismograms caused by model simplifications are relatively small if the magnitude of simplifications is adapted to the physical problem parameters (in our case, the wave frequency).

Download / Links

BibTeX Reference

@INPROCEEDINGS{,
    author = { Anquez, Pierre and Pellerin, Jeanne and Irakarama, Modeste and Cupillard, Paul and Levy, Bruno and Caumon, Guillaume },
     title = { Automatic correction and simplification of geological maps and cross-sections for numerical simulations },
 booktitle = { 2018 Ring Meeting },
      year = { 2018 },
 publisher = { ASGA },
  abstract = { Incorporating prior geological knowledge in geophysical process models often meets practical
meshing challenges and raises the question of how much detail is to be included in the geometric
model. We introduce a strategy to automatically repair and simplify geological maps and geological
cross-sections and the associated meshes while preserving elementary consistency rules. To identify
features breaking validity and/or the thin features potentially problematic when generating a mesh,
we associate an exclusion zone to each model feature (horizon, fault). When these zones overlap,
both the connectivity and the geometry of the geological layers are automatically modified. The
output model enforces specific practical quality criteria on the model topology and geometry, that
facilitates the generation of a good mesh, i.e. minimum angles and minimum local entity sizes.
Our strategy is demonstrated on an input invalid geological 2D cross-section from a real case study
model in the Lorraine coal basin. We further explore the impacts of the model modifications on
wave propagation simulation results. We show that the differences on the seismograms caused
by model simplifications are relatively small if the magnitude of simplifications is adapted to the
physical problem parameters (in our case, the wave frequency). }
}