含孔隙介质的分层半空间表面瑞利波的衰减特性  

Attenuation of Rayleigh waves in a layered half-space with a porous layer

作　　者：阎守国 谢馥励[1,2] 张碧星 

机构地区：[1]中国科学院声学研究所声场声信息国家重点实验室,北京100190 [2]北京真时科技有限公司,北京100190

出　　处：《地球物理学报》2018年第2期781-791,共11页Chinese Journal of Geophysics

基　　金：国家自然科学基金(11574343;11474308)资助

摘　　要：以分层半空间内部含有一层孔隙介质为物理模型进行数值计算,研究半空间表面瑞利波的传播和衰减特性.为更加接近实际,结合瑞利波的激发特性,确定了瑞利波的主衰减曲线,并主要以此进行规律分析.针对速度递增和含低速层这两种典型的地质模型,讨论了瑞利波的传播衰减在不同地质模型下的特性,并分析了各自的规律.结果表明,在这两种模型下瑞利波的主衰减曲线都受孔隙介质所处空间位置影响产生比较明显的变化,但衰减系数极大值对应的波长与模型的表层厚度存在较明显的线性对应关系,利用这一关系,可以在实际勘探中快速得到表层介质厚度.另外,通过对比分析还可以看到,瑞利波主衰减曲线随孔隙介质的孔隙度和渗透率的变化都强于主频散曲线的变化,表明衰减曲线对孔隙度和渗透率的变化更加敏感,理论上更加适合进行介质参数反演工作.综合对比结果,我们认为瑞利波主衰减曲线中包含了更丰富的介质参数信息,如果能够有效利用,将可以提高瑞利波勘探的准确性和应用范围.We study the propagation and attenuation characteristics of Rayleigh waves in a layered half-space with a porous layer based on the numerical simulation. Considering the excitation characteristics, we determine the main attenuation curve of Rayleigh waves and analyze its features. Focusing on two kinds of typical geological models, i. e. velocity-increase and lowvelocity-layer, we analyze the attenuation of Rayleigh waves in each model. The results show that the main attenuation curves of Rayleigh waves are influenced significantly by the location of the porous layer, while there is obvious relationship between the wavelength corresponding to the maximum attenuation coefficient and the thickness of the surface layer of the model. Hence the thickness of the surface layer should be rapidly computed in terms of this relationship. Besides, comparison shows that the main attenuation curve of Rayleigh waves is more sensitive to the changes of porosity and permeability of the porous medium, which means that theoretically the attenuation is more suitable to inversion for parameters. Therefore, the main attenuation curve contains more information of parameters of media. By using the attenuation characteristics theaccuracy and applicability of Rayleigh wave exploration can be improved notably.

关 键 词：孔隙介质 分层模型 瑞利波 衰减特性 

分 类 号：P631[天文地球—地质矿产勘探]