论文详情
早期地震偏移的目标是通过寻找地下反射面的位置来落实井位。经过半个多世纪的发展,地震偏移技术日趋精深。特别是随着叠前深度偏移的广泛应用,地震偏移结果为解释人员进行精细的地质构造描述提供了较为可靠的资料。梳理并总结了叠前深度偏移的一些重要理论和应用现状,以及为满足生产需求所发展起来的一些方法和技术。从真振幅偏移理论出发,介绍了生产中常用的Kirchhoff偏移、射线束偏移和单程波偏移等叠前深度偏移方法,特别讨论了逆时偏移的理论和应用。介绍了逆时偏移研究中涉及的一些重要技术方法,如叠前道集输出、各向异性偏移、非弹性衰减补偿、组合炮记录偏移、成像中的鬼波补偿、多次波成像等等。讨论了最小二乘偏移的理论、方法以及其面临的主要困难,分析了偏移反褶积和最小二乘偏移的区别。全波形反演是近十年来勘探地球物理研究的热点,真振幅偏移理论可以作为联系成像与反演的纽带,全波形反演的算法核心仍然是基于反演的真振幅逆时偏移。对全波形反演的一些重要问题,如低频缺失、走时反演、反射波反演、多参数反演等方面进行了探讨,介绍了该领域所取得的一些新进展。自动化全波形反演大幅简化了处理流程、降低了工作成本、提高了成像精度。更重要的是,这一技术有助于反演出高精度的定量地质模型。
Seismic migration started out with a humble goal:trying to position lateral subsurface reflectors accurately enough for exploration with a drill bit.Over time,migration became more ambitious.With the advent of prestack depth migration,we began to think of seismic imaging as a process to provide a picture of the interior of the earth.We give an overview of prestack depth migration,its theoretical foundations,application status,and technological evolution in response to production demands.Based on true amplitude migration theory,we review all the main trends of depth imaging techniques,such as Kirchhoff migration,beam migration,and one-way wave equation migration.Particularly,we focus on reverse time migration (RTM),introducing its theory and applications.We address a few important topics in RTM development,such as common imaging gather output,anisotropic migration,anelastic attenuation compensation,migrating simultaneous shooting records,ghost compensation within an RTM,and the imaging of multiples.We then discuss the theory of least-squares migration (LSM),its implementations,and the main practical issues,and compare migration deconvolution with LSM.Full waveform inversion (FWI) has been a hot topic in exploration geophysics in the past decade.We show that true amplitude migration theory plays an important role in building up the connection between imaging and inversion,and an inversion-based true amplitude RTM stays as the kernel of a FWI.We discuss several challenging topics in FWI implementation,such as cycle skipping caused by missing low frequencies in data,FWI based on only travel-time information,reflection-based FWI,and multi-parameter FWI.Much progress has been made to solve those problems.A fully automated FWI will significantly simplify processing workflow,greatly reduce production cost,and improve imaging resolution.More importantly,it will help geophysicists to approach the ultimate goal:rendering quantitatively accurate earth models with high resolution.