Wave separation

A seismic section (a common shot point collection, a common mirror point collection, or a borehole seismic section of the vertical seismic profile type VSP) is made up of different waves that must be separated from each other in order to obtain a satisfactory image of the substratum. A common shot point collection is made up of refracted waves, pseudo-Rayleigh type guided surface waves and reflected waves. It is necessary to separate the reflected waves, the refracted waves and the pseudo-Rayleigh waves to obtain a reflection image. To separate the waves, we use 2-dimensional velocity filters, polarization filters in the case of dispersive waves and filters based on singular value decomposition (SVD). Wave separation sometimes requires the determination of certain characteristics of waves such as the phase velocity, the group velocity, the dispersion curve and the identification of different wave modes, which can equally describe the substratum.

We present some applications of SVD filter, F-K filter and polarization filter:

Filtering by singular value decomposition (SVD).
Wave separation in borehole seismics by the SVD method.
Detection of cracks in a concrete block.
Vertical Seismic Profile.
Selection of a Rayleigh wave by a polarization filter.