Seismic Ray Tracing In Anisotropic Media

This paper mainly includes three research contents:seismic ray tracing forward modeling in anisotropic media,travel time inversion and static correction processing.In anisotropic media,the ray travels along the group velocity,and the group velocity parallel to energy,and it is a function of the group angle,which makes the ray formula complex and difficult to determine.Iterative bending method and improved Newton algorithm can solve this problem and overcome the high nonlinearity of anisotropy.In this paper,the ray path,wavefront and travel time are calculated by using this method.At the same time,the accuracy of the method is proved by comparing the shot gather and snapshot wavefront and travel time.In addition,oil and gas exploration has developed from 2D to 3D.Therefore,I extended to 3D to adapt to complex terrain.Finally,the ray path and travel time calculated by 2D and 3D ray tracing are applied to travel time inversion.This paper research two travel time inversion methods in anisotropic media.We all know that the problem of travel time inversion in anisotropic media is ill-conditioned and ill-posed,so this paper uses least squares method to invert firstly,and introduces covariance matrix to eliminate errors.According to the Fourier series velocity model inversion,from the actual data inversion results,the least squares method can get a higher precision velocity model.In addition,considering the influence of anisotropic parameters,by using subspace inversion method,not only the anisotropic parameters and velocity can be obtained simultaneously,but also the accuracy of inversion results can be improved.The actual data selected in this paper is the undulating surface model,so the static correction of the undulating surface model is carried out to eliminate the influence of surface elevation on the actual data.In this paper,tomographic statics are processed according to the velocity model of travel time and travel time inversion obtained by ray tracing forward modeling.The results of synthetic record simulation and real data processing show that tomographic statics can better eliminate the impact of the surface.