S-S imaging with vertical-force sources

Abstract

We show examples of S-S images created from multicomponent seismic data generated by vertical-force sources that can be quite useful to seismic interpreters. Two source types are used: vertical vibrators and shot-hole explosives. We first discuss S-S images made from data generated by a vertical vibrator and recorded with vertical receiver arrays of 3C geophones. We next show images extracted from surface-based 3C geophones deployed around this VSP well as a 3D seismic grid. The energy sources used to generate these surface 3D seismic data were shot-hole explosives. In all data examples, we observe that each type of vertical-force source (vertical vibrator and shot-hole explosive) produces abundant direct-S energy on radial and transverse geophones. We find only minimal amounts of P-wave energy on transverse-receiver data. In contrast, radial-receiver data have significant P-wave events intermingled with radial-S events. The minimal amount of P-wave noise on transverse-receiver data makes it easier to study S-S wave physics and to create S-S images with transverse-S data. The data examples focus on transverse-S data created by vertical-force sources because interpreters will find it more convenient to process and use this S-mode. Subsequent publications will assign equal weight to radial-S and transverse-S data.