||Nonhyperbolic reflection moveout of -waves:
An overview and comparison of reasons||
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Published as Center for Wave Phenomena, CWP-372 (2001)
Nonhyperbolic reflection moveout of -waves:
An overview and comparison of reasons
Sergey Fomeland Vladimir Grechka
The familiar hyperbolic approximation of
moveout is exact for homogeneous isotropic or elliptically anisotropic
media above a planar reflector.
Any realistic combination of heterogeneity, reflector curvature, and nonelliptic
anisotropy will cause departures from hyperbolic moveout at large
offsets. Here, we analyze the similarities and differences in
the influence of those three factors on
-wave reflection traveltimes.
Using the weak-anisotropy approximation
for velocities in transversely isotropic media with a vertical symmetry axis
(VTI model), we show that although the nonhyperbolic moveout due to both
heterogeneity and reflector curvature
can be interpreted in terms of effective anisotropy, such anisotropy
is inherently different from that of a generic homogeneous VTI model.