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Crs As A Tool For True Amplitude ImagingNormal access

Authors: R.S. Portugal, R. Biloti, L.T. Santos and M. Tygel
Event name: 7th International Congress of the Brazilian Geophysical Society
Session: Seismic Migration & Imaging
Publication date: 28 October 2001
Organisations: SBGf
Language: English
Info: Extended abstract, PDF ( 727.95Kb )

We present a method to obtain a true-amplitude
migration and amplitude-versus-angle (AVA) at selected
points using the attributes generated by the
Common Reflection Surface (CRS) Stack. Our approach
combines the CRS stack/inversion process
applied to multicoverage data, together with the
use of a kinematic Kirchhoff migration, to achieve
true-amplitudes (TA) at assigned depth points of
the migrated images. The proposed method consists
of the following steps: (i) apply the CRS process
to the given multicoverage data; the obtained
CRS attributes are next used to produce a simple
macro-velocity depth model; (ii) perform an unweighted
Kirchhoff migration for imaging purposes
only; for selected points on target reflectors in the
migrated image, we use the macro-velocity model
to determine, by ray tracing, common-reflectionpoint
(CRP) gathers that belong to the input data;
for these rays, we compute the incident angles and
the geometrical spreadings; (iii) go back to CRP
gathers and compensate the amplitudes for geometrical
spreading. The results permit to construct
AVA curves on the assigned CRPs. In summary,
our method is designed to aggregate amplitude information
on selected points of a reflector, after a
purely kinematic image (migration) has been obtained.
The method is tested on a synthetic inhomogeneous
layered model with good results.

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