波动方程初至波多信息联合反演方法  

First-arrival multi-information joint inversion method based on wave-equation

作　　者：张建明 董良国[1] 王建华 ZHANG JianMing;DONG LiangGuo;WANG JianHua(State Key Laboratory of Marine Geology,Tongji University,Shanghai 200092,China)

机构地区：[1]同济大学海洋地质国家重点实验室,上海200092

出　　处：《地球物理学报》2021年第7期2447-2460,共14页Chinese Journal of Geophysics

基　　金：国家重点研发计划深海关键技术与装备重点专项(2019YFC0312004);国家自然科学基金项目(41874127)联合资助.

摘　　要：地震初至波中包含着丰富的近地表速度结构信息,如何分阶段、分尺度地利用这些信息进行近地表速度建模是地震勘探中的一个关键问题.在速度反演的不同阶段,综合利用初至波中的不同信息(如走时、包络和波形等)进行联合反演,可以有效地降低反演对初始模型的依赖程度,提高近地表速度模型的反演精度.为此,本文提出了一种统一基于波动方程正演引擎的初至波多信息联合反演方法,该方法同时匹配观测和模拟的初至波走时、包络和波形信息.在不同的反演阶段选择不同的权重因子调节不同信息的权重,这样不仅降低了反演对初始速度模型的依赖,而且自然地实现了多尺度反演.在每轮反演迭代中,一次正演模拟的波场同时应用于初至波走时、包络和波形匹配,无需额外的射线追踪.同时,联合反演方法在一定程度上缓解了串联反演中目标函数漂移问题,提高了近地表速度建模的精度.The first-arrival of seismic wave contains abundant information about the near-surface structure. How to use these information to build the near-surface velocity model with different scales is a key issue in different exploration stages. Ideally, in different stages of velocity inversion, comprehensive utilization of first-arrival multi-information(such as travel time, envelope and waveform, etc.) for joint inversion can not only reduce the dependence on the initial velocity model, but also improve the inversion accuracy of the near-surface velocity model. Based on the unified seismic wave equation modeling engine, a new first-arrival multi-information joint inversion method is proposed which matches the observed and simulated first-arrival traveltime, envelope and waveform information at the same time. In different inversion stages, different weighting factors are selected to adjust the weight of different information, which not only reduces the dependence of inversion on the initial velocity model, but also realizes multi-scale inversion naturally. In every iteration of the inversion, one-time simulated wavefield are simultaneously used in first-arrival traveltime, envelope and waveform fitting. Therefore, there is no need for additional ray tracing. At the same time, the joint inversion method can partially mitigate the drift phenomenon of objective function in sequential inversion, and improve the accuracy of near-surface velocity model building.

关 键 词：近地表建模 目标函数 多尺度 联合反演 

分 类 号：P631[天文地球—地质矿产勘探]