NMO correction in anisotropic media using ray velocity

Abstract

In a homogenous transversely isotropic medium, P-wave NMO velocity depends on anisotropic parameters. Based on the approximation of Alkhalifah, P-wave traveltime correction for any offset is done by NMO velocity through a zero-offset ray. However, in anisotropic media, the velocity changes with different directions related to symmetry axis. In this paper, we present a formula to estimate NMO correction based on ray velocity instead of zero offset NMO velocity. The ray velocity can be determined for any offset using anisotropic ray tracing based on an exploding reflector model. Also, a dimensionless parameter defined by semblance analysis is applied as a third term of non-elliptical traveltime equation.Model and field experiments were performed to demonstrate the feasibility of the method. The results show that moveout correction using ray velocity is more accurate than Alkhalifah's method for long offsets. © 2009 The Authors Journal compilation © 2009 RAS.