粘弹VTI介质单程波正演模拟与照明分析

One-way wave equation forward modeling and illumination analysis in viscoelastic VTI media

实际地下介质不仅表现各向异性的特征,同时还表现粘弹性的特征,对入射波和反射波的传播及能量分布造成一定的影响。为了更加准确地分析地震波在实际地下介质中的传播规律,利用改进的单程波动方程数值模拟方法,对粘弹VTI介质模型进行qP波正演模拟以及点震源和不同角度入射平面波震源的照明度分析,并对正演及照明结果进行了对比分析。通过两组模型试验,总结了地震波在粘弹VTI介质中与在弹性各向同性介质中传播的不同之处:一方面,介质存在粘弹性会对在其中传播的地震波能量造成吸收;另一方面,介质还存在各向异性,导致地震波在介质中传播速度随方向变化,对地震波的能量分布造成影响。

The actual subsurface media always show anisotropic and viscoelastic properties which will affect the propagation and the energy distribution of the seismic wave. In order to analyze the laws of qP wave propagation in viscoelastic anisotropic media more accurately, an improved one-way wave forward modeling method is used to calculate the qP wavefield and qP wave illumination intensity of the point source and plane wave source with different incident angles in viscoelastic VTI meaia. Differences between the wave propagation in viscoelastic VTI media and elastic isotropic media are clarified by two sets of experiment： for one thing the media will absorb the energy of the seismic wave due to the existence of the viscoelastici- ty; for another the seismic wave velocity will vary with the propagation direction due to the anisotropy of the media which will affect the energy distribution of the wave.