Patent US 6,374,201

A method for 3D modeling of the impedance of a heterogeneous medium from recorded data corresponding to waves coming from the heterogeneous medium (such as a subsoil zone), in response to (for example elastic or electromagnetic) waves transmitted therein, and from an a priori 3D model of this heterogeneous medium, knowing the position of various impedance discontinuities of the medium, and after stratigraphic interpretation is disclose. The method comprises constructing a 3D geometric model comprising several foliated volumes (such as sedimentary units foliated by the deposition isochrones) with definition of the different sheets, constructing an a priori impedance model from this geometric model and from a plurality of impedance measurements taken at various depths of the heterogeneous medium (in a well for example), selecting a covariance model (exponential for example) along the sheets of the foliated volumes, and forming the optimum model by recorded data inversion using the a priori impedance model. The method can be used notably for studying the configuration of hydrocarbon reservoirs for example.