Velocity Characteristics Of Seismic Waves And Finite Difference Forward Modeling In Orthotropic Media

Seismic forward modeling is in determining the characteristics of underground medium structure and material of all kinds of cases,the research on the rules of seismic wave propagation in the underground medium,is for seismic data acquisition,processing,interpretation,th e analysis of the three major links to verify the rationality of the design of data acquisition,data processing and data interpretation reliability purpose,provide reliable seismic parameters for seismic inversion data.The present study of the anisotropic medium is mainly transversely isotropic medium(TI),but in view of the multi-component seismic data analysis results show that the actual structure of the complex underground media have approximate orthogonal anisotropy(OA)the nature of the medium,and the use of OA medium can more truly reflect the actual formation geologic features,analysis of seismic response of the orthogonal anisotropic medium is one of the effective ways to solve the complex geophysical problems.Therefore,to study the velocity and wave field characteristics of seismic wave propagation in underground orthogonal anisotropic media is the development trend of seismic exploration and the need of dealing with difficult geological exploration at present.This article is based on the basic theory of anisotropy,the use of Christoffel equation deduced OA medium three-dimensional phase velocity formula and based on the theory of principle,Crampin Berryman OA medium 3 d group velocity is deduced expressions,obtained the P wave,SV wave and SH wave group,the phase velocity of the three kinds of body wave graph,and by establishing the OA medium model,analyzed the different elastic parameters under different waveform of seismic wave,the phase velocity variation characteristics;Application in numerical simulation of seismic wave,the staggered grid high-order finite difference algorithm,and the difference scheme,the boundary conditions and stability conditions are discussed,such as selection after the perfectly matched layer absorbing boundary conditions,the use of second order time-space of high order staggered grid fourth-order finite difference method to solve the first order of OA medium speed-stress of the elastic wave equation,realized the numerical simulation of seismic wave in different media;First,a homogeneous isotropic medium model is designed for forward sim ulation,and the simulation results demonstrate the stability and effectiveness of the finite difference method with high-order staggered meshes.Then,the two-layer model composed of uniform OA medium model,isotropic medium and OA medium is designed respectively for forward simulation trial calculation,and the seismic wave field characteristics under different anisotropic parameters in the two models are obtained.The research results will provide a theoretical basis for analyzing the correlation between elastic parameters of orthotropic media and seismic wave response,provide a basis for seismic data acquisition and processing,and further promote the development of seismic wave anisotropy technology.