程玖兵,,
王腾飞
同济大学海洋地质国家重点实验室, 上海 200092
基金项目: 国家重点研发计划(2018YFC0310104)与国家自然科学基金(42074157，41630964)资助
详细信息
作者简介: 刘学义, 男, 1992年生, 同济大学博士在读, 主要从事海底多分量地震数据成像与反演方面的研究.E-mail: xueyiliu@tongji.edu.cn
通讯作者: 程玖兵, 教授, 研究方向: 地震波传播、成像和反演及其在油气资源勘探和岩石圈成像中的应用.E-mail: cjb1206@tongji.edu.cn
中图分类号: P631收稿日期:2021-01-05
修回日期:2021-04-14
上线日期:2021-09-10
Travel-time inversion for converted waves of ocean-bottom multi-component seismograms considering water-layer reverberations
LIU XueYi,CHENG JiuBing,,
WANG TengFei
State Key Laboratory of Marine Geology, Tongji University, Shanghai 200092, China
More Information
Corresponding author: CHENG JiuBing,E-mail:cjb1206@tongji.edu.cn
MSC: P631--> Received Date: 05 January 2021
Revised Date: 14 April 2021
Available Online: 10 September 2021
摘要
摘要:海底多分量地震数据在完成上-下行P/S波分离之后，基本消除了检波器端的多次波信号，但仍受到一些源端多次波的干扰.在浅水(水深在500 m以内)、软海底环境下，经海底与海面各反射一次的水层鸣震因能量较强，对反射波偏移成像与速度分析造成极大的困扰.就横波速度分析而言，含源端水层鸣震的PPS波对一次转换PS波形成主导性干扰.本文从走时反演的视角，基于声波方程建立描述PS波和PPS波的Born模拟算子，提出同时拟合这两种S波震相的反射走时反演方法及相应的梯度预条件技术.合成数据实验表明，该方法可克服源端强水层鸣震的影响，改善转换波走时拟合条件，提高横波速度反演精度.
关键词: 转换波/
水层鸣震/
波动方程走时反演/
海底地震仪/
P/S分离
Abstract:After up-down and P/S decomposition of ocean-bottom multi-component seismograms, pure up-going waves are still interfered by source-side multiples even though receiver-side free-surface related multiples are eliminated. In the setting of soft seafloor and shallow water (less than 500 m water depth), strong water-layer reverberations reflected by the seabed and sea-surface can bring great trouble to seismic imaging and velocity analysis of reflection data. In analysis of shear wave velocity, the primary converted PS waves are dominantly contaminated by source-side reverberations, namely PPS waves. This work attempts to solve these problems. From the perspective of travel-time inversion, we derive Born modeling operators for PS and PPS waves based on the acoustic wave equation, and then propose a reflection travel-time inversion method that simultaneously fits these two S-wave phases with appropriate gradient preconditioning. Tests on synthesis data show that this method can tackle strong source-side water-layer reverberations, improve the travel-time fitting for converted waves and enhance the accuracy of shear wave velocity model.
Key words:Converted waves/
Water-layer reverberations/
Wave-equation travel-time inversion/
Ocean bottom seismograph/
P/S decomposition
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