The Study On QP Wave Forward Modeling Methods In 3D VTI Media

Anisotropy is ubiquitous in earth media. Study on seismic anisotropy has become one of the leading edge directions in the field of seismology. Forward modeling simulates wave propagate in the media of earth. We can learn the relationship of characteristic of seismic propagate and the parameter of earth media from the simulating, and get the optimal approximation of real seismic recording. Studying on seismic forward modeling can help people accurately know the rule of seismic propagation. It also can verify the validity of earth model, interpret the real seismic data, predict reservoir and develop the resource. In a word, it has very important meaning in both theory and practice.This paper simulates the qP wave in 3-D transversely isotropy with a vertical axis of symmetry (VTI) media in both domains of frequency and time. In frequency domain modeling, stating with frequency-space domain qP wave equation in 3-D VTI media, the weighted mean finite difference operators which is based on conventional finite difference operators is presented. Comparing the precision of velocity dispersion of conventional finite difference operators and weighted mean finite difference is following. Then we get the weighted mean coefficient by the Gauss-Newton method in optimization theory to make the finite-difference equation phase velocity being equal to that of wave equation. The helix boundary condition and absorb boundary condition in frequency domain is adopted. In aspect of solving large sparse matrix this paper advances the improved arithmetic. The numerical experiments are given in the end of frequency domain modeling. In time domain modeling, we firstly deflate the time domain qP wave equation in 3-D VTI media. Secondly, apply the weighted mean finite difference operators which are presented former to the wave function in time domain. A new split perfect matched layer boundary condition is presented and is validated the effect in this paper. The complex model simulating in time domain is given at last. The model simulating of frequency and time domains show that the arithmetic that is given in this paper effectively suppress the numerical dispersion and successfully decrease the artificial boundary reflecton. It is supply the foundation for migriation and invertion of qP wave in 3-D VTI media.