2D three-component seismic forward modeling in TTI media based on the Lebedev grid

The conventional staggered grid finite difference method is a numerical simulation method which is often used to study seismic wave propagation.However,different components of each variable in the staggered grid is staggered defined.For undefined points,their variables need to be interpolated,which reduces the accuracy of simulation.Therefore,the 2D 3C velocity-stress elastic wave equation of the TTI media is deduced on the basis of previous studies and the Lebedev grid is used to process the high accuracy differential separation.This scheme can avoid errors caused by the wave field interpolation in the conventional staggered grid when dealing with anisotropic media and it improves the modulated precision.Meanwhile,the multi-axis perfectly matched layer (MPML) method is introduced into this method.The forward modeling of the single layer TTI medium and the complex TTI medium with the lens is carried out.The results indicate as follows: A.The Lebedev grid does not need to interpolate the wavefield when the elastic wave equation of the anisotropic medium is discrete.Compared with the conventional staggered grid method,the simulation accuracy is higher.The test shows that P-wave,fast S-wave and slow S-wave can be clearly observed when the TTI medium is simulated and the polarization direction of fast S-wave and slow S-wave is opposite.The velocity characteristics of the three kinds of waves observed in single gun record also conform to the propagation regulation of seismic wavefield; B.After introducing MPML into this method,the phenomenon of boundary reflection is effectively suppressed without affecting the simulation effect. © 2018, Editorial Department OIL GEOPHYSICAL PROSPECTING. All right reserved.