Seismic complex ray tracing in 2D/3D viscoelastic anisotropic media by a modified shortest-path method

Abstract

In a viscoelastic anisotropic medium, velocity anisotropy and wave energy attenuation occur and are often observed in seismic data applications. Numerical investigation of seismic wave propagation in complex viscoelastic anisotropic media is greatly helpful in understanding seismic data and reconstructing subsurface structures. Seismic ray tracing is one of the effective means to study the propagation characteristics of high-frequency seismic waves. Unfortunately, most seismic ray-tracing methods and traveltime tomographic inversion algorithms only deal with elastic media and ignore the effect of viscoelasticity on seismic raypath. We present a method to find the complex ray velocity that gives the seismic ray speed and attenuation in an arbitrary viscoelastic anisotropic medium, and then incorporate them with the modified shortest-path method to determine the raypath and calculate the real and imaginary traveltime (wave energy attenuation) simultaneously. We demonstrate that the complex ray-tracing method is applicable to arbitrary 2-D/3-D viscoelastic anisotropic media in a complex geological model, and the computational errors of the real and imaginary traveltime are less than 0.36% and 0.59% respectively. The numerical examples verify that the new method is an effective and powerful tool for accomplishing seismic complex ray tracing in heterogeneous viscoelastic anisotropic media.