Abstract: The method consists in building a common midpoint gather of seismic traces of which the CMP point is said given point, subjecting the traces of this gather to dynamic and/or static corrections, and characterized in that the gather associated with the given point (A) is built by recording four CMP sub-gathers associated with said given point along four angular directions (1 to 4) passing through said given point, and dynamic and/or static corrections are applied to each of the four CMP sub-gathers in order to determine, for each sub-gather, a value of the curvature and/or the velocity optimizing the energy of the trace stack of the corrected sub-gather concerned, the four values thus obtained representing the components of the stacking velocity field desired for each of the reflector elements corresponding to the given point, and characterized by a vertical propagation time t0 with reflection for zero offset.Application in particular to the exploration of a medium with a complex tectonics.

Abstract: A geophysical attribute migration method for a medium is disclosed. The method comprises forming at least one collection of seismic traces associated with an area of the medium and classified according to a predetermined criterion, and a stack section is produced on the basis of said seismic trace collection using a stacking speed field related to said area.

Abstract: A method of processing seismic signals for the analysis of moveout is presented in which waves are transmitted in a medium, reflected, received by receivers and recorded in the form of seismic traces. A string of N integers is defined having indices j lying between two limits (j.sub.min, j.sub.max) and representative of the moveouts of at least one predetermined gather of traces. A focus depth time t.sub.p for each value of j is calculated. A string of P integer numbers u is defined which determines an interval (P-1).DELTA.X. For each value of j, each trace identified by its parameters X.sub.0 and h is copied as many times as there are integer numbers u in the interval (P-1).DELTA.X. At least one static correction (dt) is applied to each of the copied traces, dependent at least on the parameters j, h and u .DELTA.X. Copying and static correction are repeated for all the values of X.sub.0 and of j.

Abstract: A seismic reflection data acquisition and processing method and device for prospecting in tectonically complex environments are disclosed. In particular, the seismic reflection data acquisition and processing method is useful for providing a summation rate tensor field and a 3D image unit, e.g. in 3D earth seismics or complex tectonics.

Abstract: A method for the determination of migration velocities in seismic processing in which a blasting point S is associated with receivers (R.sub.1 to R.sub.n) which are separated by offsets such that in a given speed range, a first set of traces derived from the blasting point and registered on the receivers, and a second set of traces in constant and colinear offset to the first set are migrated. Two migrated images of the part of the site corresponding to the two sets of traces are obtained. The two images are correlated by means of a spatial two-dimensional correlation, the result thereof determining the deviation between the migration used and the investigated velocity. The result is particularly useful in the seismic prospection of a site.

Abstract: A method of analysing and processing seismic reflection data for the determination of a high resolution spatial hyperbolicity correction velocity field.The method is characterised in that:for the set of normal moveout-corrected gathers, the maximum values of the positive and negative residues of the NMO correction are determined: a time range analysis is determined located on either side of a time t.sub.0 and of which the width is equal to not more than twice the absolute value of the maximum residual moveout,a family of 2n+1 residual correction hyperbolas or parabolas are constructed, each having its apex centered on said time t.sub.0 and, at the value of the maximum offset, presenting a value of time that is equal to one of the 2n+1 equidistant time values predetermined on the analysis range, and including the value t.sub.0 and the extreme values of said analysis range,2n+1 sets of static corrections are determined for each of the offsets, defined by the time differences presented relative to said time t.

Abstract: A system for photographing circumferential surfaces of revolution of solid objects such as core samples is of a type in which an object is rotated so as to progressively present the surface to a fixed photographic device in which a film is moved at a linear velocity synchronously with the speed of rotation of the object. The apparatus is characterized in that it includes a spray conduit for the humidification of the object during photography and a liquid tank and roller assembly for forming a thin film of fluid over the entire circumferential surface of the object during the photography thereof.