Figure shows the migration results in
the angle domain for the input data (Figure
a),
the estimated signal with the pattern-based approach
(Figure
b) and the estimated signal with adaptive
subtraction (Figure
c). By looking at the constant
angle section (X=11000 m), it appears that more multiples have been removed with
the pattern-based approach, especially below the salt where the
multiples are the strongest. The common angle gathers corroborate
this: a lot more energy from the multiples is present with
the adaptive subtraction. Note that some multiple energy remains in
both Figure
b and Figure
c where
the salt body is present. These multiples have strong curvature and
low-frequency content. These events are probably internal multiples
bouncing between the sea bottom and the top of salt. Another
pass of multiple attenuation in the image space Sava and Guitton (2005)
could eliminate these reflections.
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Finally, Figure shows a comparison of ADCIGs for the
input data with multiples (Figure
a), the estimated
primaries with the pattern-based approach (Figure
b) and
the estimated primaries with adaptive subtraction (Figure
c) outside the salt boundaries (X=4000 m). It illustrates
once again that the pattern-based approach outperform the adaptive
subtraction method with a cleaner panel.
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The Gulf of Mexico example demonstrates that the pattern-based approach is an effective tool for multiple attenuation in complex geology. Although the multiple model obtained with SRMP presented some obvious flaws (short offset amplitudes), the proposed approach is able to attenuate the multiples while preserving the primaries. In addition, comparisons in the image space after migration on ADCIGs show that the pattern-based approach gives cleaner panels than adaptive subtraction.