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We have showed that the Abelian group attributes domain
(g1'=T, g2'=T.Vnmo2 - T.Vwater2) is a good domain for
waterbottom multiples and peglegs attenuation.
We have achieved the correct timing in the mapping
between the space-time domain and
the Abelian group attributes domain.
However, the amplitude remains a problem
owing to the different velocity sensitivity
between shallow and deep parts in the velocity transform.
The geometrical progression of amplitude
between primary and multiples in
the Abelian group domain is not strictly satisfied.
One remedy to the second problem might be to
mute the far offset data along
a slanted straight line, so that the data of near/far offset have the
same recording angular aperture with respect to the source.
Beside the periodicity as discussed above, the other idea is sparsity.
By implementation of more Abelian group attributes,
events will be increasingly sparse, and primaries and multiples
will be more easily differentiated. This helps us to avoid identifying
multiples and peglegs as primaries. The next Abelian group attribute candidate
to be implemented is anelliptic factor. This would better model non-hyperbolic
effects that might be either extrinsic and due to layering, or intrinsic,
if the layered material was anisotropic.
As m=g3/(T.Vnmo4), there is still
the problem of different
sensitivity between small and large T.
It seems to me that this different sensitivity
does not offset the first one.
Since the use of the two weighting functions in the paper
is not satisfactory enough,
we need a better strategy to handle the different
velocity sensitivity between
shallow and deep parts in the velocity transform.
Next: ACKNOWLEDGMENTS
Up: Mo: Multiple attenuation
Previous: Field data
Stanford Exploration Project
11/18/1997