Abstract
Summary Sedimentary rocks encountered in exploration can be regarded as transversely isotropic (TI) media having only 5 independent elastic constants and a single symmetrical axis. Transversely isotropic phase velocity expressions exist for P-, SH- and SV-waves. Approximate explicit analytical Pwave ray velocity functions in transversely isotropic (TI) media have now been developed (Zhang and Uren, 2001 a, b). These ray velocity functions include several dimensionless constants. Unfortunately, no explicit exact analytical ray velocity functions have been formulated for P- or SV-waves propagating in TI media. In exploration seismology, explicit ray velocity functions are needed for efficient migration, velocity analysis and other seismic processing procedures. The formulae for calculating the travel times between any two points in homogeneous transversely isotropic (TI) media and for the reflection travel times from a single horizontal reflector overlain by transversely isotropic media with a vertical symmetrical axis (VTI) have been derived (Zhang and Uren, 2001 a, b). New traveltime expressions for HTI media are presented here. A new technique for velocity semblance analysis is presented to estimate the dimensionless parameters in the new NMO equation, using surface seismic survey data. The results of NMO corrections with these parameters flatten events over a large range of offsets.
Published Version
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