Generalized Diffraction-stack Migration and Filtering of Coherent Noise*
Generalized Diffraction-stack Migration and Filtering of Coherent Noise: A standard reverse time migration (RTM) image is obtained by computing the zero-lag correlation of the back-projected data with the source wavefield. The forward-modeling and back-projection operations usually are computed by a finite-difference solution to the two-way wave equation. For back projection, each recorded trace acts as a source-time history (in reverse time) of a virtual point source at the geophone location. This is a simple and easily understood migration method that most often is preferred for imaging beneath complex geology such as salt bodies. Chapter 13 highlights a recent development in diffraction migration – a reformulated approach to reverse-time migration. Here, you will find a reprint of “Generalized diffraction-stack migration and filtering of coherent noise,” by Ge Zhan, Wei Dai, Min Zhou, Yi Luo, and myself, originally published in Geophysical Prospecting. This 2014 paper describes a new approach to image migration, from the original team who developed the method. I add footnotes and a set of exercises following the reprinted piece, but the paper stands alone and deserves to be reprinted in its entirety. Special thanks to my coauthors and to Geophysical Prospecting for their kind permission to reprint this work.
Figures & Tables
This book describes the theory and practice of inverting seismic data for the subsurface rock properties of the earth. The primary application is for inverting reflection and/or transmission data from engineering or exploration surveys, but the methods described also can be used for earthquake studies. I have written this book with the hope that it will be largely comprehensible to scientists and advanced students in engineering, earth sciences, and physics. It is desirable that the reader has some familiarity with certain aspects of numerical computation, such as finite-difference solutions to partial differential equations, numerical linear algebra, and the basic physics of wave propagation (e.g., Snell’s law and ray tracing). For those not familiar with the terminology and methods of seismic exploration, a brief introduction is provided in the Appendix of Chapter 1. Computational labs are provided for most of the chapters, and some field data labs are given as well. Matlab and Fortran labs at the end of some chapters are used to deepen the reader’s understanding of the concepts and their implementation. Such exercises are introduced early and geophysical applications are presented in every chapter. For the non-geophysicist, geophysical concepts are introduced with intuitive arguments, and their description by rigorous theory is deferred to later chapters.