Analysis And Research Of Elastic Wave Propagation Characteristics In VTI Medium

The anisotropy of VTI medium will lead to the propagation time and amplitude difference of waves in different propagation directions.Therefore,in microseismic monitoring,the anisotropy of VTI media should be considered when determining the source location and mechanism.And often observed in micro seismic monitoring in place and the double coupling source fault,and based on the elastic wave equation seismic forward modeling,seismic source is usually the explosion source,but the actual medium source is complex,not only including explosive source,also includes the dc source and source of moment tensor,therefore,in the anisotropic medium how to simulate all kinds of the source of the wave field is an important content of the seismic forward modeling.This paper mainly studies the forward modeling method based on seismic moment tensor and elastic wave equation in VTI medium.The numerical simulation based on different source mechanisms can be used to study the stress characteristics and response characteristics of different source types.In order to analyze the characteristics of the point source and the moment tensor source,the analytical solution of the elastic wave equation loaded by the point source and the moment tensor source in isotropic medium is derived,and the influence of the distance between the source and the receiver on the displacement is analyzed.Of point source and source of moment tensor formula for the radiation pattern of the derivation and draw the corresponding radiation pattern graphics,analyzed the source-the direction of the receiver's influence on the displacement,this paper using numerical simulation method is the staggered-mesh finite difference method,the elastic wave equation,using the VTI media on the staggered grid space second order time of eight order difference format,the introduction of perfectly matched layer,to achieve a little bit of the source and the source load moment tensor of the elastic medium wave field simulation.The wave field under the loading mode of point source and moment tensor source in VTI medium is compared with that in isotropic medium.Finally,the wave field under the loading mode of moment tensor source is simulated in multi-layer mixed media,and the relevant conclusionsare obtained through analysis and summary.The results show that the loading mode of moment tensor source in elastic medium is more complex than that of point source.Under the loading of moment tensor source ISO,the wave field of VTI medium is completely different from that of isotropic medium.Under the loading of DC source and CLVD source,the wave field of VTI medium is the same as that of isotropic medium.Through the simulation of multi-layer hybrid medium model,draw the conclusion: the moment tensor in VTI media source under the load of wave field is more complex,the stronger the degree of anisotropy,VTI media influence on the wave field,the greater the anisotropy of VTI medium affected the recorded wave travel time and amplitude,which affect the micro source radiation pattern,so in the practical exploration should fully consider the influence of anisotropy of these factors.