Generalized Dix equation and analytic treatment of normal-moveout velocity for anisotropic media

摘要: Despite the complexity of wave propagation in anisotropic media, reflection moveout on conventional common-midpoint (CMP) spreads is usually well described by normal-moveout (NMO) velocity defined zero-spread limit. In their recent work, Grechka and Tsvankin showed that azimuthal dependence NMO generally has an elliptical shape determined spatial derivatives slowness vector evaluated at CMP location. This formalism used here to develop exact solutions for media arbitrary symmetry. For model a single homogeneous layer above dipping reflector, we obtain explicit expression valid all pure modes any orientation line with respect reflector strike. The influence anisotropy absorbed components zero-offset ray. If medium horizontally stratified, effective through Dix-type average matrices responsible interval ellipses individual layers. generalized Dix equation provides analytic basis inversion vertically inhomogeneous, media.