Depth imaging in anisotropic media by symmetric non-stationary phase shift

We present a new depth-imaging method for seismic data in heterogeneous anisotropic media. This recursive explicit method uses a non-stationary extrapolation operator to allow lateral velocity variation, and it uses the relationship between phase angle and the spectral coordinates of seismic data to allow velocity variation with phase angle. A qualitative comparison of migration impulse responses suggests that, for an equivalent cost, the symmetric non-stationary phase-shift (SNPS) operator is superior to the phase-shift plus interpolation (PSPI) operator, for very large depth intervals. To demonstrate the potential of the new method, seismic data from a physical model acquired over a transversely isotropic medium are imaged using a shot-record migration based on the SNPS operator.