Nonhyperbolic Reflection Traveltimes and Moveouts in Anisotropic VTI Media

The hyperbolic approximation of P-wave reflection traveltimes in common-midpoint gathers plays an important role in conventional seismic data processing and interpretation. It is well known that the normal moveout formula is based upon homogeneous isotropic media. The familiar hyperbolic approximation of P-wave reflection moveout is exact for homogeneous isotropic or elliptically anisotropic media above a planar reflector. Any realistic combination of heterogeneity, anisotropic coefficient, and nonelliptic anisotropy will cause departures from hyperbolic moveout at large offsets. Therefore, nonhyperbolic moveout gives exact traveltimes for elliptically anisotropic media overlaying a plane dipping reflector. In this paper, we compare a theoretical description of P-wave reflection traveltimes and degree of nonhyperbolic moveout with different anisotropic parameters.