横向各向同性介质中弹性波的物理模拟  

Physical modeling of elastic waves in transversely isotropic medium

作　　者：董良国[1] 李国治 杨泉荣 魏建新 周正仁 

机构地区：[1]同济大学海洋地质与地球物理系,上海200092 [2]中国新星石油公司石油物探研究所,南京210014

出　　处：《石油物探》1999年第1期76-84,共9页Geophysical Prospecting For Petroleum

基　　金：国家自然科学基金

摘　　要：陆相薄互层沉积在一定程度上可以用横向各向同性（TI）介质来描述。通过对一种TI介质的地震物理模拟实验，给出了该介质模型不同观测方式的实验记录，并对介质中的波场、体波速度以及反射波的时差进行了分析，发现TI介质中的波场较各向同性介质中的波场要复杂得多，三种体波在介质中的传播速度随角度的变化也不同。在不同炮检距下，qSH反射波具有相同的瞬时时差速度，而qP和qSV反射波的瞬时时差速度却随炮检距的不同而变化，但在炮检距不大的情况下，可以分别用一个统一的时差速度来近似，但该速度与介质中垂向速度无关。Landfacies thin bed sediments can be simulated to some extent with transversely isotropic (TI) media. In this paper we give experimental records of a TI medium under different observation pat-tems by means of seismic physical modeling experiments on this medium model. After an analysis of wavefield, body wave velocity and reflection wave moveout in the medium, it is found that the wavefield in TI medium is much more complicated than in isotropic medium and that the propagation velocity variations of these three kinds of body waves with angle are different. When the offset changes, qSH reflected waves have the same instantaneous moveut velocity, but the instantaneous moveout velocities of qP and qSV reflected waves change with the offset. Under the circumstance of small offset, a unified moveout velocity can be used for approximation, which has nothing to do with the vertical velocity in the medium.

关 键 词：介质 地震物理模拟 波场 地震勘探 弹性波 

分 类 号：P631.443[天文地球—地质矿产勘探] P631.41[天文地球—地质学]