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 | When is anti-aliasing needed in Kirchhoff migration? |  |
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In Figure 3a the data are migrated without triangular weighting.
The effect of operator aliasing is most evident in the seafloor arrivals.
We see precursors to the actual event. The top of
the salt dome (earlier than
s) is poorly imaged and there is more
overall speckling than in Figure 2b, suggesting that
the effects of data aliasing are compounded by operator aliasing.
Other prominent operator aliasing artifacts are seen at about
midpoints 13000 to 14000 and time 0.6 s to 0.9 s as cross-cutting dipping
events.
Figure 4 is a comparison of the anti-aliased
migration and the aliased migration
(Figure 4a is a closeup of Figure 2b, and
Figure 4b is a closeup of Figure 3a).
The seafloor precursor artifacts before
s and the cross-cutting
dipping event artifacts are marked.
The operator aliasing has been somewhat contained by limiting the
migration aperture to
in Figure 3b;
however, the seafloor event still has
a precursor, the top of the salt dome is still poorly imaged, and there
is more coherent noise than in Figure 2b.
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Gulfaper
Figure 3. (a) Kirchhoff migration
without any aperture limitation or anti-aliasing. The effect of operator
aliasing is noticeable at the seafloor where migration velocity is slow and
where there is significant operator dip. At later times, the migration velocity
is fast and there is not much operator dip, so there is no operator
aliasing.
(b) Kirchhoff migration of Gulf of
Mexico data with aperture limitation. Limiting the aperture
reduces some, but not all, of the operator aliasing at the seafloor.
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Zoom2
Figure 4. Close up of (a) the
anti-aliased migration, and (b) the standard Kirchhoff migration without
anti-aliasing. The seafloor operator aliasing artifacts and the
dipping artifacts are marked.
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 | When is anti-aliasing needed in Kirchhoff migration? |  |
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Next: Anti-aliasing is not needed
Up: GULF OF MEXICO SALT
Previous: Anti-aliased migration
2015-03-26