Research On First Arrival Tomography In TTI Media

In the region with complex surface conditions,such as the desert region,Piedmont region,degree of accuracy of the surface velocity on velocity analysis,migration imaging quality,the precision of static correction will cause varying degrees of impact,and the establishment of the accurate near surface model has become underground accurate imaging conditions.Transversely isotropic ti is exploration seismology application most extensive a kind of isotropic anisotropic medium model,is used to describe by cyclical deposition thin interbed directional arrangement of vertical fracture induced anisotropy.Now,many studies are established in VTI media,but TTI model has more universality.Therefore,the study of TTI Media will be more meaningful.In this paper,we study the basic theory of anisotropic,according to anisotropic theory,according to the elastic enough for the derivation of the equation,the wave equation in anisotropic media,the wave equations are derived for the Christoffel equation,solving the eigen value problem in VTI media phase velocity formula is obtained.Study the relation between anisotropic media group velocity and phase velocity and group angle intuitive understanding,after the VTI media transition to TTI Media,for ray tracing algorithm as the theoretical basis.The shortest path method based on graph theory can be obtained at the same time travel time and ray path and the advantages of unconditionally stable,study the anisotropic media shortest path ray tracing method.In computational grid travel time,using the Newton descent method for solving group phase relation equation,accurate phase was obtained by the group angle,so as to obtain more accurate group velocity and traveltime.The ray tracing method using in homogeneous anisotropic media and layered media and respectively with the theoretical travel time and finite difference points results,to verify the accuracy of the method,complex anisotropic media model test to verify the adaptability of method of complex media.Finally,based on the isotropic tomographic method,deduces the TTI Media tomographic inversion equations is studied by solving the equations of SIRT and LSQR method,the final choice of LSQR inversion method in this paper,regularization to constrained tomographic inverse problem is also an important issue,this paper LSQR method to study the syndromedifferent properties for multi parameters of TTI Media with different regularization,improve the linear underdetermined.In order to solve the problem that the multi parameter inversion is not uniform,the normalized matrix is introduced,which makes the unified.Finally,the sensitivity of each parameter to travel time is analyzed,which is a good foundation for the research of the inversion strategy.