Extended CIP gathers for anisotropic wave-equation migration
Extended common-image-point gathers are effective tools for analyzing model accuracy for wave-equation
imaging. The extended CIPs can be analyzed at sparse locations in the image volume, thus reducing the
computational cost of this imaging condition. A key requirement for the effectiveness of this technique
is that space-lags and time-lag extensions be analyzed simultaneously. For dip-constrained TI media,
the CIP moveout formula is similar to the one developed in isotropic media but uses the phase angle
instead of the reflection angle. Furthermore, the extended CIPs are sensitive to errors in the anisotropy
parameters and can form the basis for wavefield-based tomographic model updates.
CIPs constructed at subsurface coordinates z = 1 km and x = 3 km. Panels (a)-(d) and (e)-(h)
correspond to imaging with correct and incorrect anisotropy parameters, respectively. Panels (d) and (h)
are stacks for all shots on the surface, and the other panels correspond to individual shots.
The full paper.