Quartic moveout coefficient: 3D description and application to tilted TI media

摘要: Nonhyperbolic (long-spread) moveout provides essential information for a number of seismic inversion/ processing applications, particularly parameter estimation in anisotropic media. Here, we present an analytic expression the quartic coefficient A4 that controls magnitude nonhyperbolic pure (nonconverted) modes. Our result takes into account reflection-point dispersal on irregular interfaces and is valid arbitrarily anisotropic, heterogeneous All quantities needed to compute can be evaluated during tracing zero-offset ray, so long-spread modeled without timeconsuming multioffset, multiazimuth ray tracing. The general equation then used study azimuthally varying P-waves dipping transversely isotropic (TI) layer with arbitrary tilt” symmetry axis. Assuming axis confined dip plane, employed weak-anisotropy approximation analyze dependence parameters. linearized proportional anellipticity coefficient·…†i‐ does not depend individual values Thomsen Typically, tilted TI media above reflector highest near strike, whereas deviations from hyperbolic line are substantial only mild dips. azimuthal variation