Three-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 to 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 multiplicity of solutions for linking traces, and the lack of knowledge about the morphology of the fault and their 3-D extrapolation. It is shown that GOCAD is a powerful tool for the geologist to (1) interactively identify the inconsistencies between the 2-D interpretation of initial cross-section profiles, (2) take into account complex morphologies such as the subdivision of a fault, (3) investigate as many hypotheses as needed, and (4) obtain a realistic geometric model of a system of faults and layers.