Abstract: A method of imaging a target area of the subsoil from “walkaway” data having application to development of oil reservoirs or monitoring of geologic storage sites is disclosed. After acquisition of seismic data of walkaway type and estimation of the rate of propagation of the seismic waves in the subsoil, p illumination angles are selected. The seismic measurements are then converted to data Dp by illumination angle. The distribution of acoustic impedances best explaining data Dp is determined within the target by using a non-linear inversion which minimizes a difference between the data Dp obtained from measurements and data by illumination angle resulting from an estimation. This estimation is performed by solving a wave propagation equation from the velocity field, an acoustic impedance distribution and a pressure distribution at the level of the top of the target for each illumination angle.

Abstract: The invention is a method of estimating, from data obtained by exploration of a zone of a heterogeneous medium, a model representative of a distribution, in the zone, of at least one physical quantity, the model being free of a presence of correlated noises that may be contained in the data which has application to determining the distribution in an underground zone of acoustic impedance, propagation velocities and permeabilities, etc.

Abstract: A method of forming, from data obtained by exploration of a zone of a heterogeneous medium, a model representative of the distribution in the zone of at least one physical quantity amply free of the presence of correlated noises that may be contained in the data is disclosed. The method essentially comprises the following stages any acquisition of data giving information about certain characteristics of the zone, specification of a modelling operator which associates the response of the model with a model (synthetic data), modelling of each correlated noise by applying a specific modelling operator to a noise-generating function (n.g.f.), specification of a semi-norm in the data space, specification, in each n.g.f. space, of a norm for which each noise modelling operator constitutes an isometry, and seeking, the model and the n.g.f.