Prestack depth migration in anisotropic media by symmetric nonstationary phase shift

Robert J. Ferguson and Gary F. Margrave

ABSTRACT

A new depth imaging method for dipping transversely isotropic (TI) media is presented that is based on the symmetric nonstationary phase shift (SNPS) method of Ferguson and Margrave (1999). Their method is a cascade of two nonstationary extrapolators and is more accurate and more stable than other explicit-one-way extrapolators (Margrave and Ferguson, 1999b). Here it is adapted for depth imaging in a TI medium with no restriction placed on the degree of the anisotropy, its heterogeneity or its axis of symmetry. Depth imaging of two TI models (physical seismic data) by SNPS provides superior images to those from isotropic vertical transverse isotropy (VTI) methods.

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