Abstract: The invention relates to a method for packing and filtering geophysical events read on multi-domain records, with distribution of said events into families each having a particular geophysical significance: iso-offset or iso-incidence angle data cubes, elastic parameter cubes derived from a joint stratigraphic inversion and the like, in order to extract therefrom data on the type of subsoil, using a multivariate statistical technique. The method essentially comprises forming, by combination of geophysical variables, synthetic variables much fewer in number, which are obtained by constructing an orthogonal vector base in each of the sets of analysis constituted by the data of each of the families, wherefrom is derived the formation of an orthonormal vector base (new attributes) for filtering and describing said geophysical events. The invention is applicable to geological interpretation or to interpretation of an underground reservoir, from seismic measurements or logs for example.

Abstract: The invention relates to a method for packing and filtering geophysical events read on multi-domain records, with distribution of said events into families each having a particular geophysical significance: iso-offset or iso-incidence angle data cubes, elastic parameter cubes derived from a joint stratigraphic inversion and the like, in order to extract therefrom data on the type of subsoil, using a multivariate statistical technique. The method essentially comprises forming, by combination of geophysical variables, synthetic variables much fewer in number, which are obtained by constructing an orthogonal vector base in each of the sets of analysis constituted by the data of each of the families, wherefrom is derived the formation of an orthonormal vector base (new attributes) for filtering and describing said geophysical events. The invention is applicable to geological interpretation or to interpretation of an underground reservoir, from seismic measurements or logs for example.

Abstract: A Method of measuring local similarities between seismic trace cubes (3D survey) obtained from a volume of an underground zone, corresponding to prestack data or to repeated seismic surveys (4D survey). For each point of the volume considered, the method comprises a) extracting, from each seismic trace cube, a volume neighborhood centered on a point, referred to as current point, and consisting of a set of seismic traces in limited number; b) applying an analysis technique referred to as (GPCA) allowing defining synthetic variables; and c) determining a coherence value from the synthetic extracted variables measuring the local similarity between the seismic trace cubes extracted from the volume neighborhood of the current point. The coherence value thus calculated is assigned to the current point. The coherence values of all of the current points form a coherence cube. An application is finer monitoring of the evolution with time of a reservoir under development.

Abstract: The invention is a method for facilitating recognition of objects, using a discriminant analysis technique to classify the objects into predetermined categories. A learning base comprising objects that have already been recognized and classified into predetermined categories is formed with each category being defined by variables of known statistical characteristics. A classification function using a discriminant analysis technique, which allows distribution among the categories the various objects to be classified from measurements available on a number of parameters, is constructed by reference to the learning base. This function is formed by determining the probabilities of the objects belonging to the various categories by taking account of uncertainties about the parameters as intervals of variable width. Each object is then assigned, if possible, to one or more predetermined categories according to the relative value of the probability intervals.

Abstract: A Method of measuring local similarities between seismic trace cubes (3D survey) obtained from a volume of an underground zone, corresponding to prestack data or to repeated seismic surveys (4D survey). For each point of the volume considered, the method comprises a) extracting, from each seismic trace cube, a volume neighborhood centered on a point, referred to as current point, and consisting of a set of seismic traces in limited number; b) applying an analysis technique referred to as (GPCA) allowing defining synthetic variables; and c) determining a coherence value from the synthetic extracted variables measuring the local similarity between the seismic trace cubes extracted from the volume neighborhood of the current point. The coherence value thus calculated is assigned to the current point. The coherence values of all of the current points form a coherence cube. An application is finer monitoring of the evolution with time of a reservoir under development.

Abstract: A method for obtaining, by means of an inversion process, an optimum model of a physical characteristic in a heterogeneous medium (the impedance of an underground zone in relation to waves transmitted in the ground for example), by taking as the starting point an a priori model of the physical characterized that is optimized by minimizing a cost function dependent on differences between the optimized model which is sought and the known data, considering the a priori model. Construction of the a priori model comprises correlation by kriging between values of the physical quantity known at different points of the medium along discontinuities (strata directions). Uncertainties about the values of the physical quantity in the a priori model in relation to the corresponding values in the medium follow a covariance model that controls the inversion parameters more quantitatively. The characteristics of the covariance model are defined in connection with the structure of the data observed or measured in the medium.

Abstract: Method for facilitating recognition of objects, using a discriminant analysis technique to classify them into predetermined categories.