Least-squares reverse-time migration based on reflection theory
DUAN Xinbiao1,2, WANG Huazhong1, DENG Guangxiao3
1. Wave Phenomena and Intelligent Inversion Imaging Group(WPI), School of Ocean and Earth Sciences, Tongji University Shanghai 200092, China; 2. Sinopec Geophysical Research Institute, Nanjing, Jiangsu 211103, China; 3. Sinopec Northwest Company, Urumqi, Xiujiang 830011, China
Abstract：Least-squares migration can provide an accurate solution to the model space based on the linear inversion theory.Compared to conventional migration methods,least-squares migration can increase imaging resolution,improve amplitude preservation and reduce migration artifacts.The classical least-squares migration is based on the linearized expression of the scattered wave,and its goal is essentially estimating the scattering intensity of underground medium.While real underground medium is mainly layered,the target of least-squares migration in production is reflection-coefficient imaging.This paper focuses on the difference between linearized expression method of scattering theory and reflection theory.According to the requirement of migration imaging in actual production,then the demigration method based on linearized expression of reflection theory and the least-squares RTM process for estimating the reflection coefficient are established.Sigsbee2a model test shows a good imaging effect using the proposed method.An application of three-dimensional field data shows that the least-squares RTM method is better than RTM.The string beads imaging has better convergence effect,and the deep large faults and small interbed faults are more clearly described.
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