基于随机介质模型的统计分析在深反射地震中的应用

Application of statistical analysis based on random medium model in deep seismic reflection data

深反射地震勘探是揭示地球深部构造的一种地球物理探测方法.由于不同于沉积地层的反射特征,深反射地震资料的解释需要不同于浅层水平层状介质的解释方法.基于随机介质模型的统计分析为深反射地震解释提供了新的途径.本文首先介绍了地球深部结构中非均质性的统计特性研究成果,阐述了随机介质模型的基本概念及二维随机介质的建立方法,讨论了随机介质模型参数的含义.通过正演模拟的方法分析了随机介质的地震响应特点,对比实际深反射地震资料可对地壳中反射透明区、上下地壳界面、莫霍面反射以及非均质入侵体的地震响应提出合理解释.然后总结了从反射地震数据估算随机介质参数的方法及存在的问题,结合实例论述了随机介质参数分析在深反射地震解释中的作用.最后探讨了该方法的优缺点及应用前景.

Deep seismic reflection exploration is a geophysical exploration method to reveal the deep structure of the earth. Since reflections from deep show different characteristics from homogenous sedimentary strata, unconventional interpretation methods that are different from shallow horizontal layered media are needed for the interpretation of deep seismic reflection data. The statistical analysis based on the random medium model is a novel methodology for deep seismic reflection data interpretation. In this paper, we introduce some research results of the statistical characteristics of the heterogeneity in the deep structure of the earth. Then, we expound on the basic concept of the random medium and the method of establishing a two-dimensional random medium velocity model as well as the meaning of major parameters. Compared with the seismic response of the random medium velocity model, the reflection transparent zone, upper and lower crust interfaces, Moho reflections and heterogeneous intrusion bodies in the crust can be interpreted from field deep seismic reflection data. Afterward, we summarize the methods of estimating random medium parameters from reflection seismic data and their limitation. The role of random medium parameter analysis in deep reflection seismic interpretation is discussed with some successful examples. Finally, we discuss the advantages and disadvantages, and application prospects of this method.