The Anisotropic Earth

Figure  2(a) shows conclusively that the Earth we know and love is definitely anisotropic. What we see in this figure is a comparison between an isotropic and an anisotropic migration of a small piece of a seismic section and well as a direct comparison to to data from a VSP-CDP transform section. The 3D vertical seismic profiles (VSP's), as shown in Figure  2(b), could provide virtually all of the additional anisotropic parameters in cone relative to the central well location. As shown in Figure  2(c) VSP's provide a superb approach for tying surface seismic data to reflecting horizons and are perhaps one of the best methods for both recognizing and proving the existence of anisotropy in real rocks. Unfortunately, VSP's provide information about anisotropy only at a relatively sparse set of well locations. To construct full wide area 3D anisotropic modes necessitates that we find methods for using recorded seismic data to extend the estimation area.