二维粘弹性随机介质中的波场特征分析

The analysis of the wave field characteristics in 2-D viscoelastic random medium

通过交错网格有限差分正演,模拟了平面地震波在二维粘弹性随机介质模型中的传播及其自激自收时间记录.为研究粘弹性随机介质模型中的波场特征,我们在理论记录(垂直分量)剖面上选取两个时间区段;在这两个不同的时间区段上,分别计算剖面的三个统计特征(横向中心频率、纵向中心频率、波场能量相对值).这样,对应每一个粘弹性随机介质模型,我们均可计算得到6个不同的波场特征量.我们通过在二维粘弹性随机介质中的正演模拟,研究当自相关长度以及粘弹吸收系数变化时,对应的上述波场特征量的变化特点,最终得出了若干结论.

Trough the staggered-mesh finite difference simulations of the wave equations, simulated the propagation of the seismic wave and the relevant zero offset time record in the 2D viscoelastic random medium models. To study the wave field characteristics of 2-D viscoelastic random medium, we divide up the theoretic recording sections (vertical component) into two different time sectors, and separately calculated and extracted the three statistical characteristics (Horizontal center frequency, vertical center frequency and relative magnitude of the wave field energy) in the two different time sectors. In this way, corresponding to every single viscoelastic random medium model, we can calculate and gained 6 different wave field characteristic quantities. Via the forward modeling in the 2-D viscoelastic random medium, we studied the change features of the wave field characteristic quantities as changing the media's autocorrelation length and the viscoelastic absorb coefficient, and gained several conclusions finally.