Tomographic determination of seismic velocity models with kinematic wavefield attributes
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Beschreibung
For the transformation of recorded seismic reflection data into a depth image,
a seismic velocity model is required. In this thesis, a new tomographic method
for the determination of such velocity models is presented which makes use of
traveltime information in the form of kinematic wavefield attributes. These
attributes are the coefficients of second-order traveltime approximations and
can be extracted from the seismic data by means of coherence analyses, e.g.,
by applying the common-reflection-surface (CRS) stack method.
Compared to conventional reflection tomography which requires picking of
reflection events in the prestack data, the use of kinematic wavefield
attributes leads to considerable practical advantages: the attributes required
for the tomographic inversion are taken from the CRS stack results at a number
of pick locations in the stacked section. For each considered data point, these
attributes can be interpreted in terms of the second-order traveltimes of an
emerging wavefront due to a hypothetical point source in the subsurface. During
the inversion process, a model is found that minimizes the misfit between these
data and the corresponding quantities modeled by dynamic ray tracing.
In the thesis, the complete theory of the method, as well as practical
applications are presented. Starting with an overview of the required aspects
of ray theory and the CRS stack method, the general concept of the new
tomographic inversion approach is developed. The method is then discussed in
detail for the case of 1D, 2D, and 3D tomographic inversion and the entire
process of deriving a velocity model is demonstrated on a synthetic and on a
real 2D seismic dataset.
Autor*in
Eric Duveneck
Themen in »Tomographic determination of seismic velocity models with kinematic wavefield attributes«
Kinematic wavefield attributes Paraxial ray theory Reflection seismics Tomography Velocity models