The Research Of Grid Tomographic Inversion Method In Elastic Media

In the research of seismic wave propagation,it is usually assumed that the subsurface medium is acoustic medium,that is,the wave field only propagates with longitudinal wave in the subsurface medium,and the influence of transverse wave is neglected.However,in the real case,the waves propagating in the underground medium have not only the p-wave information,but also the s-wave information.Therefore,the elastic vector wave mesh tomographic inversion method developed in this paper is based on the conventional longitudinal wave travel time tomographic,and the vector wave mesh tomographic inversion method with the joint constraint of vertical and horizontal waves is developed to provide a high-precision migration velocity field for pre-stack imaging.Based on the theory of elastic media and the framework of seismic inversion theory,this paper research the grid tomographic inversion method in elastic media with imaging domain.In the case of velocity inaccuracy,the Gaussian beam migration in elastic medium is used to obtain the angle domain common image gather set of the initial migration profile.This paper also infer the relation between the residual curvature and the traveling time residual of the angle domain common imaging gathers.Finally,the appropriate ray tracing method and regularization method are used to construct the grid tomographic inversion equation and solve it,so as to realize the velocity update of vertical and horizontal waves.In the method,the reflection point position and dip angle information are fitted directly according to the common imaging gathers,no need to pick up the layer,and the grid tomographic flow with the joint constraint of the vertical and horizontal waves is optimized,which improves the accuracy and efficiency of the inversion.The results show that the elastic vector wave grid tomographic inversion method in this paper can accurately invert the velocity model of vector waves,and its precision and efficiency are greatly improved compared with the traditional tomographic inversion method.