3-DIMENSIONAL GEOMETRIC MODELING OF A FAULTED DOMAIN - THE SOULTZ-HORST EXAMPLE (ALSACE, FRANCE)

This paper describes an example of 3-D modeling using GOCAD software, a geometric modeler designed for geological surfaces. The problem is t o build a geometrically consistent model of a fault and layers system starting from faults' traces on cross sections, cross sections derived from seismic profiles, and drillhole data. A methodology is proposed and discussed. The main problems in modeling faults are the multiplici ty of solutions for linking traces, and the lack of knowledge about th e morphology of the fault and their 3-D extrapolation. It is shown tha t GOCAD is a powerful tool for the geologist to (1) interactively iden tify the inconsistencies between the 2-D interpretation of initial cro ss-section profiles, (2) take into account complex morphologies such a s the subdivision of a fault, (3) investigate as many hypotheses as ne eded, and (4) obtain a realistic geometric model of a system of faults and layers.