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In Chapter I showed that in 2D, specularly-reflected multiples, when
migrated with the velocity of the primaries, map to subsurface offsets with the
opposite sign to that of their surface offset in Subsurface-Offset-Domain Common-Image
Gathers (SODCIGs).
In Angle-Domain Common-Image Gathers (ADCIGs) they map with curvature towards
increasing depths. In this chapter I extend these ideas to 3D and show,
with a 3D synthetic prestack dataset,
that specularly-reflected multiples in 3D have a similar behavior
with an interesting addition: in 3D ADCIGs, the primaries and multiples
exhibit different azimuth dependence as a function of the dip of the
reflecting interface generating the multiple. This attribute is used to
discriminate between primaries and multiples in 3D ADCIGs and therefore
help in the attenuation of the multiples.
2007-10-24