Abstract: Device and method for processing 4-dimensional (4-D) seismic traces. The method includes receiving at least two vintages of seismic traces recorded by seismic receivers for a same subsurface area, wherein said seismic receivers are located at the ocean floor; applying up-down deconvolution to each of said vintages of seismic traces to obtain a representation of a reflectivity of said subsurface area from each vintage of seismic traces; and redatuming the up-down deconvolution result of each vintage from the ocean floor to a desired water depth of the ocean to reduce one or more changes in said seismic traces associated with water layer variations between recordings of said series of seismic traces. The redatumed seismic data is used to generate one or more images representing characteristics of said subsurface area.

Abstract: Device and method for processing 4-dimensional (4-D) seismic traces. The method includes receiving at least two vintages of seismic traces recorded by seismic receivers for a same subsurface area, wherein said seismic receivers are located at the ocean floor; applying up-down deconvolution to each of said vintages of seismic traces to obtain a representation of a reflectivity of said subsurface area from each vintage of seismic traces; and redatuming the up-down deconvolution result of each vintage from the ocean floor to a desired water depth of the ocean to reduce one or more changes in said seismic traces associated with water layer variations between recordings of said series of seismic traces. The redatumed seismic data is used to generate one or more images representing characteristics of said subsurface area.

Abstract: A method of processing geophysical data including determining the azimuth of a mirror symmetry plane within the earth from the geophysical data having sets of geophysical data acquired with different source-receiver azimuths. The data are processed to determine attributes of the geophysical data that are azimuth-dependent. One azimuth-dependent attribute of the geophysical data is selected, and a value of the source-receiver azimuth about which the selected attribute exhibits mirror symmetry is determined. This locates a mirror symmetry plane within the earth. The value of the source-receiver azimuth may be determined by generating an objective function indicative of the difference between the actual value of an attribute at one azimuth and the value predicted for that attribute at that azimuth using a trial estimate of the azimuth of a mirror symmetry plane, and finding the azimuth of a mirror symmetry plane that minimizes the objective function.

Abstract: A method of processing geophysical data comprises determining the azimuth of a mirror symmetry plane within the earth from the geophysical data that comprises sets of geophysical data acquired with different source-receiver azimuths. The data are processed to determine attributes of the geophysical data that are azimuth-dependent. One azimuth-dependent attribute of the geophysical data is selected, and a value of the source-receiver azimuth about which the selected attribute exhibits mirror symmetry is determined. This locates a mirror symmetry plane within the earth. The azimuth which the selected attribute exhibits mirror symmetry may be determined by generating an objective function indicative of the difference between the actual value of an attribute at one azimuth and the value predicted for that attribute at that azimuth using a trial estimate of the azimuth of a mirror symmetry plane, and finding the azimuth of a mirror symmetry plane that minimises the objective function.

Abstract: A method of determining the polarisation directions of the fast and slow shear waves arising from shear wave splitting due to anisotropy, said directions defining a natural coordinate system, the method comprising the steps of: a) recording at least two components of each shear wave, in a recording coordinate system, b) calculating the value of &thgr;, being the angle of rotation between the natural coordinate system and the recording coordinate system, for which the Lp norm of the rotated traces is minimised if p is less than 2, or maximised if p is greater than 2.

Abstract: A method for acquisition of seismic data from an area surveyed using a group of seismic energy sources and a group of seismic streamer cables, particularly a marine area, includes forming a first group A from at least two elements of either seismic energy sources S or seismic streamer cables C having a spacing X between said elements, forming a second group B from at least two of the other elements of sources S or cables C than that forming group (A), spacing the elements in group B a distance equal to X multiplied by the number of elements in group A, forming a group C from at least two subgroups each consisting of a group A, spacing said subgroups in group C in distance equal to the distance between two elements in group B multiplied by the number of elements in group B, the spacing between two adjacent subgroups being equal to the lateral distance between midpoints between the subgroups, and forming further groups as desired D, E, F etc.

Abstract: A method of assigning seismic traces obtained by means of one or more seismic sources (1) and receivers (2) wherein, a plane containing each source (1) and receivers (2) is divided into a regular array of regions (12-18), for example a rectangular array referred to cartesian coordinates (X-Y). The regions cover at least a middle portion of a line (11) joining each source (1) to each receiver (2). Diagonals (19-25) intersect the line (11) at respective intersection points and offspring traces are allocated to these points.