VTI介质弹性波波场分解的空间域算法

Space domain algorithm of elastic wave-field decomposition in VTI media

本文在波数域波场分解方法的基础上,研究了VTI介质中弹性波波场准纵波、准横波分解的空间域算法。通过求解克里斯托弗尔方程,得到准纵波与准横波的偏振方向及波数域波场分解算子,对其进行反傅里叶变换得到空间域波场分解算子;由空间域波场分解算子与原始波场的褶积即可得到对应不同波型的具有多分量特征的波场分解结果。由于在不同空间位置处采用不同的分解算子,故本文算法能适应各向异性参数随空间位置变化的情况。分别采用均匀VTI介质模型、层状VTI介质模型和Sigbee2A VTI模型进行了模拟试算,模拟结果验证了算法的有效性。

Based on wave number domain wave-field decomposition,qP wave and qS wave decomposition in transversely isotropic media with a vertical symmetry axis is implemented in space domain in this paper.The decomposition operators in wave number domain are constructed using the polarization vectors evaluated by solving the Christoffel equation,then IFFT is applied and decomposition operators in space domain are derived.Wavefield decomposition with multi-component characteristics can be obtained by convolution operation between spatial operator varied with spatial locations and multi-component wavefield.Since the algorithm developed in this paper utilizes corresponding decomposition operators in each grid point,it can adjust to the condition that anisotropic parameter varies spatially.Elastic wavefield model tests in homogeneous VTI media,stratified VTI media and anisotropic version of sigsbee2A model have proven the efficacious of this algorithm.