0uartic Moveout Coefficient in TI Media with Arbitrary Spatial Orientation

摘要

Nonhyperbolic (long-spread) moveout benefits parameter estimation in anisotropic media. Here, we examine the quartic moveout coefficient A_4 that controls the magnitude of nonhyperbolic moveout of pure (nonconverted) modes. We present an analytic expression for the quartic moveout coefficient of a horizontal reflector in TI media with arbitrary spatial orientation. Our result is valid for arbitrary strength of anisotropy, homogeneous media. And it contains all former results of TI media for a horizontal reflector. Therefore, we can compute the quartic coefficient A4. The quartic coefficient has a much more complicated character than the NMO-velocity ellipse. Compared with weak anisotropic approximate quartic coefficient of P-wave, the different result is obtained. For strong anisotropy, the azimuthal varying exact solution A_4 is governed by the spatial orientation of symmetry axis and the Thomsen's anisotropic parameters, and does not just depend on the spatial orientation of symmetry axis. The combination of this analytic solution with numerical solution could provide the basis for further development of TI investigation and seismic anisotropic survey and interpretation.