利用最小平方基准面延拓压制自由表面多次波Ⅰ:海底观测地震数据  

Elimination of free-surface multiples using least-squares redatuming,PartⅠ:Ocean-bottom seismic data

作　　者：朱峰 程玖兵[1] ZHU Feng;CHENG JiuBing(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》2022年第8期3123-3138,共16页Chinese Journal of Geophysics

基　　金：国家自然科学基金(42074157);国家重点研发计划(2018YFC0310104)资助.

摘　　要：海底多分量地震采集技术被广泛用于海洋地质调查、油气资源勘探以及地震与海啸等灾害监测领域.然而,自由表面效应导致地震观测数据中多次波干扰很强,影响一阶散射理论基础上的速度建模和偏移成像.本文基于数据驱动的地震干涉原理,在最小平方反演理论框架下提出消除自由表面和上覆介质影响的基准面延拓方法,结合海森算子与点扩散函数揭示其工作机理.针对海底分离的上、下行波记录,在无需进行多次波分离或分阶提取情况下,迭代反演获得在海底虚拟观测的叠前地震数据.理论模型合成数据实验结果表明,该方法能够有效压制源端自由表面与海水层的影响,提高有效信号的分辨率,进而改善地震成像质量.Ocean-bottom multi-component seismic observation is widely used in marine geological investigation,petroleum exploration,and disasters(like earthquake and tsunami)monitoring.However,the free-surface effects lead to strong multiples in the seismic data recorded at the ocean bottom,which affect velocity model building and seismic migration using the first-order scattering theory.In this paper,based on the principle of data-driven seismic interferometry,a least-squares redatuming method is proposed to mitigate the influence of free-surface and overburden medium,and the work mechanism is revealed by Hessian operator and point-spread-function.Using the separated up-and down-going wavefield recordings,the virtually observed prestack seismic data at the ocean bottom are obtained by iterative inversion without separation of different-order surface-related multiples.Numerical examples of synthetic data show that the proposed approach can effectively suppress the source-sided free-surface effects,enhance the resolution of desired signal,and thus improve the quality of seismic imaging.

关 键 词：自由表面 多次波 海底观测 最小平方基准面延拓 地震干涉 

分 类 号：P631[天文地球—地质矿产勘探]