非均匀地质体散射波特征初探

Preliminary study on scattering wave characteristics of heterogeneous geologic bodies.

中国地质大学地球物理与信息技术学院, 北京100083

School of Geophysics and Information Technology, China University of Geosciences, Beijing 100083, China

对于复杂非均匀介质,可以利用地震散射波来研究其分布和性质。对散射波的基本概念进行了阐述;利用统计学方法对复杂非均匀介质进行了描述,构造了二维随机介质模型,其自相关长度a和b分别描述了水平和深度方向非均匀异常的平均尺度;利用有限差分法分别对不同自相关长度和不同主频的模型进行了正演模拟, 结果表明,散射波清晰可见,随着自相关长度和主频的改变,随机介质表现出不同的散射特征;抽取单道地震记录,对散射波特征及其振幅特征进行了分析,结果表明,散射波分布于整个地震记录,振幅随相关长度改变表现出不同的特征。

For complex heterogeneous medium, the distribution and characteristics of its heterogeneity can be studied by seismic scattering wave. In this paper, the principal definitions of scattering wave were presented, complex heterogeneous medium was then described using statistical method, 2-D random model of medium was constructed, where the mean scale of heterogeneous anomalies in horizontal and vertical direction was described by its autocorrelation lengths a and 6 respectively, finally, these models with different autocorrelation length and dominant frequency were forward modeled using finite-difference method. The results showed that scattering wave was clear while the characteristic of random medium was varying with the change of autocorrelation length and dominant frequency. The characteristic of scattering wave and its amplitude was analyzed by extracting the seismic record of single trace. It is shown that scattering wave was distributed over total seismic record, its amplitude behaved different characteristics corresponding to different autocorrelation lengths.