二维复杂黏弹性各向异性介质中的地震射线追踪  

Seismic ray tracing in 2D complicated viscoelastic anisotropic media

作　　者：李兴旺[1] 吴建鲁 ZHOU Bing 白超英[1,3] LI XingWang;WU JianLu;ZHOU Bing;BAI ChaoYing(School of Geology Engineering and Geomatics,Chang’an University,Xi’an 710054,China;Department of Earth Sciences,Khalifa University of Science and Technology,POBox 2533,Abu Dhabi,UAE;Institute of Computing Geophysics,Chang’an University,Xi’an 710054,China)

机构地区：[1]长安大学地质工程与测绘学院地球物理系,西安710054 [2]Department of Earth Sciences,Khalifa University of Science and Technology,POBox 2533,Abu Dhabi,UAE [3]长安大学计算地球物理研究所,西安710054

出　　处：《地球物理学进展》2021年第2期489-498,共10页Progress in Geophysics

基　　金：国家自然科学基金重点项目(41830101);Khalifa University of Science and Technology under Award(CIRA-2018-48);陕西省自然科学基金项目(2021JQ-245);中央高校基本科研业务费(300102269109)联合资助.

摘　　要：实际地层中传播的地震波普遍存在速度各向异性和能量衰减现象,因此基于弹性介质假设条件下的地震射线正反演算法具有一定的局限性,而研究黏弹性各向异性介质中的地震波传播规律可为揭示地下结构提供更加可靠的理论依据.射线追踪技术是揭示高频地震波传播特性的有效手段之一,然而绝大多数研究仅限于弹性介质.针对黏弹性各向异性介质,本文首先给出了一种射线速度和振幅衰减的计算方法,然后结合改进型最短路径算法,在实空间内实现了计算复杂介质模型中地震波(qP,qSV,qSH)的射线路径和传播走时以及能量衰减(虚走时).该算法适用于复杂黏弹性各向异性介质.误差分析结果显示,实走时的最大相对误差小于0.13%,虚走时的最大相对误差小于0.55%,表明该算法具有较高的计算精度.In a viscoelastic anisotropic medium,velocity anisotropy and wave energy attenuation occur and are often observed in applications of seismic exploration.The common seismic ray-tracing methods and traveltime tomographic inversion algorithms are not applicable to such media due to use of the assumption of elastic media.Numerical investigation of seismic wave propagation in complicated viscoelastic anisotropic media is greatly helpful to understanding seismic data and reconstructing the underground structures.Seismic ray-tracing method is one of the effective means to study the propagation characteristics of high-frequency seismic waves.Unfortunately,most of ray-tracing methods only deal with elastic media.In this paper,we present a method to calculate the ray velocity and ray attenuation in 2D viscoelastic anisotropic medium,and then apply the modified shortest-path method to determine the ray path and calculate the real-and imaginary-traveltime(wave energy attenuation).We show that the ray-tracing method is applicable to 2D viscoelastic anisotropic media in a complicated geological model.The computational errors of the real-and imaginary-traveltime are less than 0.13%and 0.55%respectively,which indicates that the new method has high computational accuracy for numerical simulation of seismic wave propagation.

关 键 词：黏弹性各向异性介质 振幅衰减 改进型最短路径算法 地震射线追踪 

分 类 号：P315[天文地球—地震学]