最小二乘叠前深度偏移成像理论与方法

发布时间：2018-03-26 09:09

本文选题：散射场表达　切入点：逆散射成像　出处：《石油物探》2017年02期

【摘要】：地震波成像的目的首先是定位反射界面或散射点的空间位置,描述地下地质体的几何结构;然后是估计地下介质的物性参数,主要是与速度和密度相关的参数;最终是与岩石物理结合描述含油气储层。以地震波传播的散射场表达以及逆散射成像为切入点,首先给出散射波的表达形式,讨论了逆散射成像的本质与逆散射成像所需要的叠前地震观测数据及对应的观测方式;然后给出一般的线性化最小二乘叠前深度偏移(Least-squares Prestack Depth Migration,LS_PSDM)基本理论框架,只要能给出用Green函数计算的波传播算子,就可以实现线性化的LS_PSDM;接着讨论了当前广受关注的最小二乘逆时深度偏移(Leastsquares Reverse Time Migration,LS_RTM)方法,给出了最小二乘偏移成像的迭代实现方法和保反射界面结构的总变差正则化方法以及数值结果;最后分析了基于反射波估计反射系数的成像方法和基于散射波估计散射强度的成像方法的差异,指出针对勘探地震介质特征和波场特征的成像方法是最具实用性的方法,逆散射成像应该在此基础上进行。基于散射波的成像方法能否满足储层描述的要求,有待进一步研究工作的检验。
[Abstract]:The purpose of seismic wave imaging is to locate the space position of reflection interface or scattering point to describe the geometric structure of underground geological body, and then to estimate the physical parameters of underground medium, which are mainly related to velocity and density. Finally, it is combined with rock physics to describe oil and gas reservoir. With the expression of scattering field and inverse scattering imaging of seismic wave propagation as the breakthrough point, the expression form of scattering wave is given. In this paper, the essence of inverse scattering imaging, the pre-stack seismic observation data and the corresponding observation methods for inverse scattering imaging are discussed, and then the basic theoretical framework of Least-squares Prestack Depth migration LS-PSDM is given. As long as the wave propagation operator calculated by Green function can be given, the linearized LSSP PSDM can be realized, and then the least square inverse time depth migration (LSSD) method, which is widely concerned, is discussed, and the least squares Reverse Time migration method is discussed. The iterative realization method of least square migration imaging, the total variation regularization method of reflection-preserving interface and the numerical results are given. Finally, the difference between the imaging methods based on reflection wave estimation and scattering intensity estimation is analyzed. It is pointed out that the imaging method based on seismic media and wave field characteristics is the most practical method. Inverse scattering imaging should be carried out on this basis. Whether the imaging method based on scattering wave can meet the requirements of reservoir description needs to be tested by further research work.
【作者单位】：波现象与反演成像研究组(WPI)同济大学海洋与地球科学学院;油气藏地质及开发工程国家重点实验室成都理工大学;
【基金】：国家重点基础研究发展计划(973计划)(2011CB201002) 国家自然科学基金项目(41374117,41604100) 国家科技重大专项(2011ZX05005-005-008HZ,2011ZX05006-002,2011ZX05023)共同资助~~
【分类号】：P631.44

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