多分量震源和检波器数据弹性波高斯束偏移  

Elastic Gaussian-beam migration of multicomponent-source and-receiver data

作　　者：石星辰 毛伟建 张延保 田宝卿 SHI XingChen;MAO WeiJian;ZHANG YanBao;TIAN BaoQing(Chinese Academy of Sciences,Innovation Academy for Precision Measurement Science and Technology,State Key Laboratory of Geodesy and Earth,s Dynamics,Research Center for Computational and Exploration Geophysics,Wuhan 430077,China;China Earthquake Administration,Institute of Geophysics,Beijing 100081,China)

机构地区：[1]中国科学院精密测量科学与技术创新研究院,大地测量与地球动力学国家重点实验室,计算与勘探地球物理研究中心,武汉430077 [2]中国地震局地球物理研究所,北京100081

出　　处：《地球物理学进展》2024年第5期2059-2068,共10页Progress in Geophysics

基　　金：国家自然科学基金(42130808,42204115,42104114)联合资助。

摘　　要：当前,弹性多分量高斯束偏移的研究主要集中于PP(纵波-纵波)和PS(纵波-横波)波型,这仅是完整弹性波成像的一个子集.这些方法通常采用标量源,即仅产生纯P波的爆炸源,因此波型分离仅需要在接收端执行.然而,全面的弹性波成像还应涵盖SP(横波-纵波)和SS(横波-横波)波型.作为完整的弹性波场的一部分,SP和SS波能够从不同视角提供认识地球内部结构的能力.为了获得各个波型(包括PP、PS、SP和SS)的弹性波成像结果,本文将传统的仅在检波器端采用多分量设备的弹性高斯束偏移方法拓展至震源和检波器均使用多分量设备的情形.这种拓展可在缺乏局部界面的区域直接生成丰富的S波波型,且传播更深.基于弹性Kirchhoff-Helmholtz积分以及震源端与检波点端的完备边界条件,本文推导了适用于自由表面、海底以及自由空间模型的波场延拓与波型分离公式.在偏移过程中,该方法可自动实现源端和检波点端的波型分离,无需事先对数据进行P/S波的单独分离.此外,为解决与S波相关的极性反转问题,本文应用了适用于张量形式的矢量互相关成像条件.所提方法的有效性在两个合成数据测试中得到验证.Multicomponent Gaussian beam migration methods of elastic waves are currently mainly focused on PP/PS imaging,which is a subset of full elastic-wave imaging.Owing to the employment of pure P-wave explosive sources,these methods only require mode decomposition on the receiver side.However,elastic wave imaging also includes SP and SS cases.SP and SS waves,as part of the complete elastic wavefield,can provide valuable complementary supplementary insights to conventional PP and PS images,because each wave mode offers a distinct illumination pattern,a unique reflectivity behavior,and various amounts and types of information about the geology and rock/fluid properties.To obtain complete reflection elastic-wave images,we propose an extension of the elastic Gaussian beam migration method to multicomponent source and receiver seismic data.The use of multicomponent sources allows for the generation of rich direct-S modes in areas without local interfaces and the ability to send strong S-waves into the deep subsurface.To implement this method,we initially formulate continuation and mode decomposition formulations for free-surface,ocean-bottom,and free-space models.These are derived from the elastic Kirchhoff-Helmholtz integral coupled with corresponding complete boundary conditions on both the source and receiver sides.Such a framework allows for the decomposition of both sides to be automatically performed during migration.With our approach,multicomponent data are decomposed into PP-,PS-,SP-and SS-waves during migration without prior separation,leading to more accurate results.Furthermore,we introduce a vector cross-correlation imaging condition in tensor form to address the polarity reversal issue associated with converted waves.We demonstrate the effectiveness of the proposed method using two synthetic data tests on the free-space model,which corresponds to the case of finite-difference modeling with an absorbing top boundary.It is important to note that multicomponent wavefields are excited separately in a time-series m

关 键 词：弹性高斯束 偏移 矢量震源 

分 类 号：P631[天文地球—地质矿产勘探]