True-amplitude Kirchhoff migration: analytical and geometrical considerations
Thomas Hertweck
ISBN 978-3-8325-0512-7
163 Seiten, Erscheinungsjahr: 2004
Preis: 40.50 Eur
Stichworte/keywords: Reflection seismics , True-amplitude migration , Seismic inversion , Aperture and boundary effects , Common-Reflection-Surface stack
An important task in seismic reflection imaging
is to estimate subsurface structures from the
prestack data. This means that the reflection
events in the recorded data have to be transformed
into images in the depth domain, the reflectors.
A geometrically appealing approach for the
corresponding process is Kirchhoff migration which
is based on an integral solution of the wave
equation. Applied in its original purely kinematic
form, this process provides a structural image of
the target region under investigation. However,
Kirchhoff migration is also able to handle the
amplitude-related aspects of wave propagation,
thus allowing to assign physically sound amplitude
values to reflector images.
In such a true-amplitude
migration, the geometrical spreading effects are
removed from the input data during
the imaging process and, thus, reflector amplitudes
become basically a measure of the angle-dependent
reflection coefficient. Commencing with
the basics of wave propagation and ray theory, a
complete description of Kirchhoff migration is
presented. By relating the strict mathematical
derivation of true-amplitude Kirchhoff migration
to clear geometrical concepts, the gap between the
originally graphical migration schemes and the
nowadays available analytical descriptions based on
a stationary-phase evaluation is closed. Further
aspects relevant to the correct recovery of
amplitudes in depth migration, such as the handling
of topography and irregular geometries,
are explained in a mathematical as well as in a
geometrical manner. Finally, Kirchhoff migration is
integrated into a seismic reflection imaging workflow
based on the data-driven common-reflection-surface
(CRS) stack method.
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