Print this pagePre-Stack Seismic Modeling of a Carbonate Platform, an Example from the Vercors Massif (France)
VIRLOUVET, BRUNO, JEROME GUILBOT, and HUBERT ARNAUD
The aim of this paper is to show results from an integrated multi-disciplinary study concerning the seismic modeling of a realistic 2D geological model. The approach which involves an impedance model building, a pre-stack seismic modeling and seismic inversions, is based on the study of outcrops from a carbonate platform.
To build the geological model, we focused on the urgonian limestones (Barremian - lower Aptian) and their basement situated on the leeward side of the platform, on the south-western part of the Vercors massif. The outcrops show a semi-continuous exposure of the stratal anatomy from the inner to the outer-slope of the platform. Stratal pattern study, associated with cartography and correlations of fifth-order cycles, allowed to build a 16 kilometers long and about 800 meters thick cross-section.
By sampling the different lithofacies, rock physic properties (Vp, Vs, porosity and density) were measured in laboratory. Velocity and density models were built according to the internal organisation of the different parasequences. To generate the pre-stack synthetic dataset, a 2D finite differences scheme was used with a 35 Hz zero-phase ricker as a seismic source.
Usual as well as AVO processings were performed to obtain a time migrated profile. Stratigraphic inversion and reservoir attributes analyses were carried out on this profile and results were compared to the initial impedance model. In particular, this study shows up that the interpretation of the seismic profile can be misled by tuning effects introduced by thickness and facies variations.