交错网格与旋转交错网格对VTI介质波场分离的影响分析

利用交错网格有限差分和旋转交错网格有限差分进行各向异性介质弹性波场数值模拟时， 质点振动速度分量与应力张量的网格节点定义方式均不相同， 从而对各向异性波场分离效果产生不同的影响. 针对这一问题， 本文以具有垂直对称轴的横向各向同性(VTI)介质的波场分离为例， 首先分析了两种网格的参数定义方式以及VTI介质波场的分离过程； 其次， 详细研究和分析了这两种网格的参数定义方式对各向异性介质波场分离的影响， 并依据波前面连续性以及波场分离效果等方面， 通过数值模拟实验对该影响进行分析验证. 结果表明， 旋转交错网格的参数定义方式更有利于进行各向异性介质波场数值模拟和波场分离. 

Effects of staggered-grid and rotated staggered-grid on the wavefield separation in VTI media

Wavefield separation is an important part of multi-component seismic data processing， and the wavefield numerical simulation method is one of the necessary tools to this process. When staggered-grid finite difference scheme and rotated staggered-grid finite difference scheme are utilized to elastic wavefield simulation in anisotropic media， the definition of the particle velocity components and that of the stress tensor are different among these two grids. Furthermore， these two types of definitions will affect the wavefield separation. So we take the case of transversely isotropic media with a vertical axis (VTI media) as an example to analyze. Firstly， we analyze the parameter definition of these two grids and details about the wavefield separation in VTI media. Then， we focus on the analysis on the separation effects caused by the different parameter definition of these two grids. Considering the aspects of wavefront continuation and the purity of wavefield separation， numerical experiments are utilized to verify the results. Finally we draw the conclusion that the parameter definition of rotated staggered-grid is more beneficial to the anisotropic numerical simulation and the wavefield separation.