VERTICAL SEISMIC PROFILING—SEPARATION OF P‐ AND S‐WAVES*

In vertical seismic profile's (VSP's) shot with a large source offset, rays from shot to receiver can have large angles of incidence. Shear waves generated by the source and by conversions at interfaces are likely to be recorded by both the vertical and the horizontal geophones. Varying angles of incidence may give strong variations in the recorded amplitudes. Separation of P‐ and SV‐waves and recovery of their full amplitudes are important for proper processing and interpretation of the data. A P‐S separation filter for three‐component offset VSP data is presented which performs this operation. The separation filter is applied in the k‐f domain and needs an estimate of the P‐ and S‐velocities along the borehole as input. Implementation and stability aspects of the filter are considered. The filter was tested on an 1800 m offset VSP and appeared to be robust. Large velocity variations along the borehole could be handled and results were superior to those obtained by velocity filtering.