More reliable shear-wave data from VSPs using the CIPHER technique

It has long been recognized that fracture systems in rocks can significantly influence the flow of fluids in the subsurface. The observation of seismic shear waves, recorded with three-component multilevel geophones in boreholes, provides information on seismic anisotropy, which may be caused primarily by preferred orientations of microcracks (Crampin 1986). However, as a complementary tool to standard P-wave vertical seismic profiles (VSPs) (Hardage 1985; CasselI 1984), shearwave VSPs with horizontal vibrators require additional survey time and processing costs.