We computed 2-D stacked migrated sections when the anisotropy in
the upper layer of the velocity model used for computation of
the recorded wave field is the
same
as the anisotropy in the velocity model used for migration. In this case, migrated interface coincides nearly
perfectly with the interface in the model used for computation
of the recorded wave field. The length of the migrated interface
is dependent on the illumination by rays that differs for different
types of anisotropy.
We compared 2-D stacked migrated sections when the anisotropy in
the upper layer of the velocity model used for computation of
the recorded wave field is
different
from the anisotropy in
the velocity model used for migration. In this case migrated interface is shifted and deformed more
by wrong guess of isotropic velocity than wrong guess of
HTI anisotropy in the model used for migration.
We tested 3-D Kirchhoff prestack depth migration in a simple 3-D model
with success. We also tested 3-D migration with profile line step
twice enlarged (from 0.025 km to 0.050 km). The migrated section computed with 0.050 km step for monoclinic
anisotropy contains greater residua of individual sections used for
stacking than migrated section computed for triclinic
anisotropy.
Acknowledgments
The author thanks Ludek Klimes and Ivan Psencik
for great help throughout the work on this paper.
The research has been supported by
the members of the consortium Seismic Waves in Complex 3-D Structures