Research On Multi-component Pre-stack Depth Migration Of Seismic Waves

As an important part of seismic wave data processing technology,migration imaging attracted attention from the beginning of the seismic exploration.Multi-wave and multicomponent seismic imaging technology is a method that is highly anticipated by the industry.It has been widely used in small-scale structural exploration,lithology prediction,fluid identification,and crack detection.The technology can adapt to complex subsurface medium conditions,providing more media information far beyond single component or single waveform imaging,and its vertical component can achieve conventional longitudinal wave imaging effects,while other components can compensate for the lack of the single longitudinal wave imaging and enhance the imaging of underground media structures.Accuracy,thus solving many problems that are difficult to solve with longitudinal waves,has extremely high research value and economic benefits.In the multi-wave multi-component seismic imaging system,the pre-stack depth migration technique based on the wave equation continuation theory of wave equations is more developed.In this paper,the research on the two-dimensional two-component one-way wave pre-stack depth migration theory can be divided into two parts.Firstly,the longitudinal and transverse wave decomposition of isotropic media is deduced and realized,including the scalar and vector separation of the wave field during forward modeling,and the scalar and vector separation of seismic data.The scalar decomposition is mainly based on Helmholtz theory,and the vector decomposition is mainly established.Above the decoupled equivalent elastic wave equation.At the same time,after in-depth study of the staggered grid difference method,this paper points out the two natural defects of the staggered grid and gives the corresponding correction methods.The first is the component time difference problem,that is,because the components are defined at different positions,the wave-type starttimes are inconsistent,so that the longitudinal and transverse waves cannot be completely separated.The second is the source loading problem,that is,the theoretical single-wave mode source loading method cannot be in the interlaced network.The lattice excites pure longitudinal waves and transverse waves.Secondly,on the basis of the above research,the separated longitudinal and transverse seismic data are respectively subjected to P-P wave and P-SV wave pre-stack depth migration.This paper implements Split Step Fourier Method(SSF),Fourier Finite Difference Method(FFD),and Generalized Screen in Single Square Root(SSR).Propagator Method(GSP),the double-square root(DSR)mainly implements the split-step Fourier method.Finally,the theory and algorithm involved in this paper are verified by the horizontal model,the mantle model and the ground fissure model,and good results are obtained.