Abstract: A Balanced Surface Method: A New Way to Improve Your Structural Maps Interpretations

Jean-Claude Lecomte, Jean-Franois Mondy, Chakib Bennis, Michel Leger

A well drawn sedimentary layer, folded and faulted without internal deformation can be unfolded and restored to its initial state. The structural geology team of the Institut Francais du Petrole has developed new software, PATCHWORK, which allows the verification of the geometrical coherence of structural maps by balancing geological surfaces. This methodology is simpler and the domain of application is larger than 2-D balancing of cross sections.

The method is based on the fact that an actual faulted and folded layer was at the time of its deposition a continuous level. The studied geological surface is first piecewise interpolated with parametric functions and then sampled into a grid of points along the isoparametric curves. Faults are taken into account in this processing because the parametrization is built according to their borders. Then, the flattening is performed piecewise. Isoparametric curves of the surface (approximated with chord lines) are mapped onto curves in the flattening plane with preservation of some geometrical features: cross angles, geodesic curvature at each sample point, and chord length for sample curves. The different flat pieces are finally combined by means of rotations and translations to reconst uct a prior initial state and check the global geometrical coherence of the faulted and folded studied layer.

Using the example of a case study in the Cordilleran thrust belt, we will show all the steps of this balancing geological surface methodology implemented in PATCHWORK.

AAPG Search and Discovery Article #90986©1994 AAPG Annual Convention, Denver, Colorado, June 12-15, 1994