结合Marchenko聚焦的非线性最小平方基准面延拓方法  

Nonlinear least-squares redatuming method combined with Marchenko focusing

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》2023年第11期4677-4690,共14页Chinese Journal of Geophysics

基　　金：国家自然科学基金(42074157);中国科学院战略性先导科技专项(XDA14010203)资助。

摘　　要：基准面延拓旨在通过模型驱动或数据驱动的方法消除上覆介质对地震信号造成的畸变或影响,进而重构基准面上的虚拟观测数据.针对非线性波场效应(如层间多次波),模型驱动的基准面延拓方法对地下速度模型精度提出严苛的要求,实用性较差.如果检波器布设面与基准面恰好重合,数据驱动的虚源法能够自适应干涉消除波场在上覆介质中的非线性传播效应.然而,由于反射地震观测系统不够完备,通常会在重构数据中引入串扰噪声.针对上覆介质具有强非线性波场效应、基准面位于观测面与目的层之间任意深度的一般情况,本文将Marchenko方法和最小平方基准面延拓(LSR)相结合,先估算地表到基准面的上、下行格林函数,而后利用稀疏约束LSR方法克服观测系统和上覆地层的影响,在压制层间多次波的同时高精度重构基准面上的虚拟观测数据.层状模型合成数据实验展示了非线性波路径的干涉抵消机制,透镜体模型合成数据实验检验了该方法在压制上覆异常体多次散射效应、校正深部反射信号畸变的有效性.Redatuming aims to eliminate the distortion or influence of the overburden media on the seismic signal and to reconstruct the virtual observed data at the datum level using a model-driven or data-driven method.For nonlinear wavefield effects,such as internal multiples,the model-driven method requires an accurate overburden velocity model,which is often unattainable in practice.If the recording surface with geophones coincides with the datum level,a data-driven virtual-source method can eliminate the wavefield's nonlinear effects in the overlying medium by adaptive interferometry.Nonetheless,due to the incompleteness of the reflection seismic geometry,crosstalk artifacts are usually introduced into the reconstructed data.For the general situation with strong nonlinear wavefield effects in the overburden media and a datum locating at any depth below the recording surface,we choose to combine Marchenko method and least-squares redatuming(LSR).The up-going and down-going Green's functions from the surface to the datum are estimated via Marchenko focusing,and then virtual data on the datum,free from internal multiples,is reconstructed.Example on a layered model reveals the interferometry mechanism of the nonlinear wavepaths.Additionally,the example on a model with a high-velocity lens demonstrates the effectiveness of the proposed method to remove the overburden effects including multi-scatterings from the anomalous body.

关 键 词：最小平方基准面延拓 层间多次波 Marchenko聚焦 格林函数 

分 类 号：P631[天文地球—地质矿产勘探]