Forward Simulation Study Of TI Medium

With the increasing of exploration target complexity,it is imperative to improve the imaging accuracy and resolution of various geological structures and lithologies.Sedimentary rocks or oriented fractures,which include anisotropic information,should be taken into accout.The anisotropic information is of great value in seismic velocity modeling,migration and inversion.Transversely isotropic media(TI media)is a common medium in sedimentary rocks.It is divided into transversely isotropic media with vertical symmetry axis(VTI media),transverse isotropic media with horizontal symmetry axis(HTI media)and transversely isotropic medium with an oblique axis of symmetry(TTI medium).The seismic response of TI media can be described by the elastic wave equation of anisotropic media,but in practice,the calculation cost is too much with the use of elastic waves to describe the seismic response because of the complexity of velocity model of the longitudinal and transverse waves and the matrix and parameters which is used for describing the anisotropic medium and also it need the velocity model of the transverse wave and so on.Therefore,it’s valuable of using the qP wave equation to describe the seismic response of anisotropic media and it’s great significant for seismic migration imaging.The TTI medium introduces a polarization angle parameter.When the polarization angles are 0 degree and 90 degree,it is a VTI medium and an HTI medium.The qP wave equations of VTI media and TTI media have two forms:one is the longitudinal-transverse wave coupling equation and the other is P-wave equation.The main research in this paper is the second one.The principle is to set the shear wave velocity along the axis of symmetry to zero,and derive the qP wave equation of VTI medium and TTI medium,and then study its seismic response.The advantage of numerical modeling of TTI media over VTI media is the introduction of polarization angle parameters.For complex geological models,such as oblique crack arrangements,the TTI medium takes into account the polarization angle(the angle between the axis of symmetry and the z-axis),so the seismic response of modeling will also be more reasonable.This paper is aimed at the current problems in seismic exploration.The modeling of TI media in anisotropic media is carried out.The seismic response of VTI media and TTI media is simulated by qP wave equation and applied to complex models.The analysis summarizes the advantages of using the TTI media method to simulate than VTI media method.The current research still needs to be improved and does further research.