初至波走时层析成像对初始模型的依赖性  

The Dependence of first arrival travel time tomography on initial model

作　　者：刘玉柱[1] 丁孔芸[1] 董良国[1] 

机构地区：[1]上海市同济大学海洋地质国家重点实验室,200092

出　　处：《石油地球物理勘探》2010年第4期502-511,共10页Oil Geophysical Prospecting

基　　金：国家自然科学基金(批准号:40804023);同济大学海洋地质国家重点实验室课题(批准号:MG20080205);教育部“新世纪优秀人才支持计划”(批准号:NCET-05-0384);“国家重点基础研究发展规划项目”(编号:2006CB202402)共同资助

摘　　要：在层析反演过程中,尤其是射线层析反演过程中,很多因素会影响反演效果,初始模型就是其中的一个重要影响因素。本文主要参考Jannane等对波形反演目标函数性态分析的研究方法,通过一系列理论模型实验,分析初至波走时层析成像对初始模型的依赖性,讨论简单、高效的层析初始模型选取问题,并进一步提出以下层析成像初始模型的选取策略:①首先对存在的地质模型做平滑处理,得到介质的背景场信息(也可以结合先验信息采用其他方式(如梯度模型)作为背景场信息);②从地质模型中减去背景场信息以得到扰动场;③对扰动场做低通滤波得到扰动场的长波长分量;④将扰动场的长波长分量加上背景场信息得到层析初始模型。最后通过理论模型数值实验与实际资料处理证实该选取策略的合理性和优越性。During tomography inversion process,especially during ray tomography inversion process,many factors could affect inversion results,the initial model is just one of the important influence factors.By mainly referring the Jannane's study methods for the performance analysis of waveform inversion object function and through a series of theoretical model experiments,the dependence of first arrival travel time tomography on initial model was analyzed,then simply and effectively selecting tomography initial model was discussed and the further selection strategy of the tomography initial model was presented in this paper,the whole process can be summarized as below:①At first to smooth the existing geological model and obtain background field information of the medium (The background field information can also be obtained by integrating the prior information with other mode,such as gradient model);②To subtract background field information and obtain disturbed field;③To conduct low-pass filtering for disturbed field and obtain long wavelength component of the disturbed field;④By adding the long wavelength component of the disturbed field and background field information to obtain tomography initial model.The theoretical model data simulation and field data processing proved rationality and advantages of the selected strategy.

关 键 词：初至波 走时 射线 层析成像 反演策略 初始模型 

分 类 号：P631.44[天文地球—地质矿产勘探]