The Research Of Gaussian Beam Migration In Anisotropic Media

Seismic exploration technology is always the research emphasis in the geophysics,as one of the important ways to find oil and gas reservoirs.With the development of seismic exploration technology,the exploration targets are mainly about small and medium-sized complex reservoir,which cause higher requirement of seismic exploration technology.Seismic imaging technology is to convert the vast amounts of seismic data into seismic imaging profiles,which reflect the underground geological structure.As we all know,traditional seismic imaging techniques were mostly based on the hypothesis that the earth medium is isotropic,while a large number of observations and experiments have shown that the earth's interior medium is widespread anisotropic.If we use traditional imaging methods based on isotropic hypothesis to process seismic data of anisotropic area,it will lead to the phenomena of reflected wave can't be present on the right place and the diffracted wave can't convergent well,which will also cause bad influence on the following seismic data processing and interpretation.In addition,because we have to deal with the huge amounts of seismic data,so we should not only consider the imaging accuracy,but also the computational efficiency.As a ray migration method emerged in recent years,Gaussian beam migration(GBM)method not only retains flexible efficient advantages and ability to imaging steep structures of the ray migration method,but also can deal with caustic area.GBM has very high application prospect and research value,because its imaging accuracy has improved a lot relative to the Kirchhoff migration method,which is close to the precision of one-way wave migration.In this paper,we mainly research Gaussian beam migration methods in anisotropic media.On the one hand,we expanded the application range of the Gaussian beam method.On the other hand,we also consider its practicality.To extend GBM to the anisotropic media,the main research content in this paper is:(1)Based on wave equation,we derived the kinematic and dynamic ray tracing equations in isotropic and anisotropic media,and introduced the expression and basic properties of Gaussian beam(2)On the basis of the prior work,we derived post-stack and pre-stack Gaussian beam migration imaging formulas in anisotropic media,combining with the anisotropic ray tracing equations,and we also verified its validity by model trial.(3)In order to take the vector characteristics of multi-component seismic data into consideration,we derived the anisotropic multi-component seismic data imaging formula without wave-field separation,which was based on the idea of elastic Kirchhoff migration method.And verified the feasibility of this method by model trial.(4)In this paper,we also discussed the influence of the parameter field,selection criterion of initial beam width,beam center spacing and the ray parameter interval on anisotropic GBM methods.