Study Of Ray Tracing Method In The VTI Medium

The research direction of seismic wave field mainly includes two aspects: one is wave field forward modeling,namely positive problem;the other is wave field parameter inversion,namely inverse problem.The forward study of seismic wave field can test the reliability of various interpretation results and the correctness of the inversion algorithm,which provides a solid theoretical basis for the actual seismic data processing and underground structure prediction.The seismic wave forward modeling method can be divided into wave equation forward modeling and ray tracing forward modeling,and the main content of this paper is to carry out wave field forward modeling of complex geological model by ray method.Seismic ray method is widely used in seismic exploration theory and practice.The traditional ray theory is based on the homogeneous isotropic medium as the basic assumption,the wave field for fast and effective approximation.This simple ray theory has been unable to meet the growing demand for production practice.In recent years,high-precision seismic exploration has received great attention and development,in which the ray theory is also from the isotropic medium getting closer to the real formation of anisotropic media development,based on complex medium ray tracing wave field simulation become Gradually mature.To achieve high-precision seismic exploration,it is necessary to take into account the media anisotropy,to study its role in the process of seismic wave propagation,to produce the impact,which will be applied to practice them.The study of paper mainly focused on two aspects: anisotropy of the medium and complex structure of the model.This paper also introduced the causes and classification of the anisotropic medium,anisotropic elastic theory and the anisotropic ray theory;then derived the basic equation of ray,the corresponding relationship between VTI elastic parameters,Thomsen anisotropic parameters and the formulas of group velocity,phase velocity in VTI medium based on the Snell theorem,Fermat's principle,the Huygens principle.This paper also performed a detailed demonstration of the functional relationship between the phase velocity and group parameters in the VTI anisotropy medium.The program used the incident angle as an independent variable to research on the effect of Thomsen parameter epsilon,delta and gamma on the phase and group velocity of q P wave,q SV wave and q SH wave phase.Then through the establishment of different geological model of VTI medium,the paper applied the test ray method for wave field simulation and discussed the rules of seismic wave propagation in anisotropic media which had certain significance for the practice.