三维TI介质中多波走时层析成像  

Seismic multi-wave traveltime tomography in 3D TI media

作　　者：黄国娇 孙江兵 白超英[3] 钱卫 

机构地区：[1]河海大学地球科学与工程学院地质科学与工程系,江苏南京211100 [2]江苏省地质资料馆,江苏南京210018 [3]长安大学地质工程与测绘学院地球物理系,陕西西安710054

出　　处：《石油地球物理勘探》2018年第1期63-72,共10页Oil Geophysical Prospecting

基　　金：国家自然科学基金项目(41504038);江苏省自然科学基金项目(BK20150799);中央高校基本科研业务费专项资金项目(2017B12014)联合资助

摘　　要：传统的各向异性层析成像是在弱各向异性假设下,主要利用走时信息进行线性反演,忽略了介质横向变化,反演结果可信度不高。为此,研究了三维TI介质中多波走时层析成像技术。将各向同性介质中的分区多步不规则最短路径算法推广至三维TI介质中,实现多次透射、反射以及转换波的追踪计算,采用各向同性地震多震相走时层析成像技术,结合有关群速度、相速度偏导数计算,通过联合多波走时同时反演5个各向异性弹性参数。无论是射线路径和走时的追踪计算,还是反演方程的建立,或是雅克比矩阵的计算,该方法都未假设介质为弱各向异性,并且每次迭代都重新追踪射线路径和走时,并计算雅克比矩阵元素。因此,适用于TI介质多波走时层析成像。数值模拟结果表明,多波走时资料的联合反演可有效提高成像的空间分辨率。The conventional anisotropic tomography is based on a weak anisotropy assumption,mainly uses the traveltime to carry out linear inversion and ignores the lateral changes in the media,so inversion results are usually not reliable.Therefore,we study a multi-wave traveltime tomography in 3D TI media.The multi-step irregular shortest path method in isotropic media is extended to 3D TI media to trace multi-wave(reflected wave,transmitted wave,and converted wave)arrivals,and the algorithm for inversion in isotropic media is used.Incorporating with the equation for phase and group velocity derivatives,5 anisotropic elastic parameters are inverted simultaneously by multiwave traveltimes.This method does not assume that medium is weakly anisotropic whether in ray tracing and traveltime calculation,or in an inversion equation establishment,or in Jacobian matrix calculation.What is more,ray paths and traveltimes are re-tracked at each iteration,and Jacobian matrix elements are updated.So this method is suitable for multi-wave traveltime tomography in 3D TI media.Numerical test results indicate that the proposed method can improve the imaging spatial resolution.

关 键 词：TI介质 多波走时 弹性参数反演 走时层析成像 

分 类 号：P631[天文地球—地质矿产勘探]