Wavefield-extrapolation methods can produce
Angle-Domain Common-Image Gathers (ADCIGs).
These ADCIGs are a
function of the *half-aperture angle*, that is, the average
between the incidence angle and the reflection angle.
This chapter presents a method to compute ADCIGs for
converted-wave data (PS-ADCIGs) after imaging with
wave-equation migration.
The method exploits the robustness of computing
2-D isotropic single-mode ADCIGs,
and incorporates both the P-to-S velocity ratio (),
and the local image-dip field.
This method also maps the final PS-ADCIGs
into two different angle-domain common-image gathers,
the first ADCIG is function of the P incidence angle,
the second one is function of the S reflection angle.
Results with both
synthetic data and real data show
the practical application
for converted-wave angle-domain common-image
gathers.
The main contribution of this chapter is independent
of the migration algorithm implemented. The approach is valid
as long as the migration
algorithm is based on wavefield downward continuation,
and the final prestack image is a function of the horizontal
subsurface offset.

12/14/2006