Imaging And Velocity Analysis By Target Oriented Wavefield Inversion PDF Download
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Author | : Yaxun Tang |
Publisher | : Stanford University |
Total Pages | : 239 |
Release | : 2011 |
Genre | : |
ISBN | : |
Download Imaging and Velocity Analysis by Target-oriented Wavefield Inversion Book in PDF, ePub and Kindle
This thesis develops a novel target-oriented inversion framework that uses wavefields as carriers of information to image both low-wavenumber component (a.k.a. background velocity) and high-wavenumber component (a.k.a. reflectivity) of the earth model in complex geological settings, such as subsalt regions. I address the problem of reflectivity imaging with target-oriented wavefield least-squares migration, and the problem of velocity estimation with target-oriented wavefield tomography. Reflectivity images of the subsurface are commonly produced by prestack depth migration. When the overburden is complex and the reflectors are unevenly or insufficiently illuminated, the migration operator alone is inadequate to provide an optimal image. I tackle the problem of distorted illumination in reflectivity imaging by wavefield least-squares migration. I formulate least-squares migration in the image domain and solve it in a target-oriented fashion. In the image-domain formulation, explicit computation of the Hessian operator (the resolution function that measures the illumination deficiency of the imaging system) is the most important and challenging step. I develop a novel method based on phase encoding to efficiently and accurately compute the target-oriented Hessian operator. The Hessian operator is then used to recover the reflectivity by iterative inverse filtering. I regularize the inversion with dip constraints, which naturally incorporate interpreted geological information into the inversion. Accurate imaging of the reflectivity also requires an accurate background velocity model. High-quality velocity model-building in complex geology requires wavefield-based velocity analysis to properly model band-limited wave phenomena. However, the high cost and lack of flexibility of target-oriented model-building prevent this method from being widely used in practice. I overcome the cost and flexibility issues of wavefield-based migration velocity analysis by developing target-oriented wavefield tomography. Target-oriented wavefield tomography is achieved by synthesizing a new data set specifically for velocity analysis. The new data set is generated based on an initial unfocused target image and by a novel application of generalized Born wavefield modeling, which correctly preserves velocity kinematics by modeling both zero and non-zero subsurface-offset-domain images. The new data set can be synthesized for a chosen target region with velocity inaccuracies. The reduced data size and computation domain, therefore, greatly improve the efficiency and flexibility of wavefield tomography, allowing fast and interpretation-driven interactive wavefield-based velocity analysis, where different geological scenarios or hypotheses can be tested in quasi-real time. The proposed target-oriented inversion framework successfully estimates subsalt velocities and recovers subsalt reflectivities from distorted illumination from 2-D synthetic and 3-D field data.
Author | : Yaxun Tang |
Publisher | : |
Total Pages | : |
Release | : 2011 |
Genre | : |
ISBN | : |
Download Imaging and Velocity Analysis by Target-oriented Wavefield Inversion Book in PDF, ePub and Kindle
This thesis develops a novel target-oriented inversion framework that uses wavefields as carriers of information to image both low-wavenumber component (a.k.a. background velocity) and high-wavenumber component (a.k.a. reflectivity) of the earth model in complex geological settings, such as subsalt regions. I address the problem of reflectivity imaging with target-oriented wavefield least-squares migration, and the problem of velocity estimation with target-oriented wavefield tomography. Reflectivity images of the subsurface are commonly produced by prestack depth migration. When the overburden is complex and the reflectors are unevenly or insufficiently illuminated, the migration operator alone is inadequate to provide an optimal image. I tackle the problem of distorted illumination in reflectivity imaging by wavefield least-squares migration. I formulate least-squares migration in the image domain and solve it in a target-oriented fashion. In the image-domain formulation, explicit computation of the Hessian operator (the resolution function that measures the illumination deficiency of the imaging system) is the most important and challenging step. I develop a novel method based on phase encoding to efficiently and accurately compute the target-oriented Hessian operator. The Hessian operator is then used to recover the reflectivity by iterative inverse filtering. I regularize the inversion with dip constraints, which naturally incorporate interpreted geological information into the inversion. Accurate imaging of the reflectivity also requires an accurate background velocity model. High-quality velocity model-building in complex geology requires wavefield-based velocity analysis to properly model band-limited wave phenomena. However, the high cost and lack of flexibility of target-oriented model-building prevent this method from being widely used in practice. I overcome the cost and flexibility issues of wavefield-based migration velocity analysis by developing target-oriented wavefield tomography. Target-oriented wavefield tomography is achieved by synthesizing a new data set specifically for velocity analysis. The new data set is generated based on an initial unfocused target image and by a novel application of generalized Born wavefield modeling, which correctly preserves velocity kinematics by modeling both zero and non-zero subsurface-offset-domain images. The new data set can be synthesized for a chosen target region with velocity inaccuracies. The reduced data size and computation domain, therefore, greatly improve the efficiency and flexibility of wavefield tomography, allowing fast and interpretation-driven interactive wavefield-based velocity analysis, where different geological scenarios or hypotheses can be tested in quasi-real time. The proposed target-oriented inversion framework successfully estimates subsalt velocities and recovers subsalt reflectivities from distorted illumination from 2-D synthetic and 3-D field data.
Author | : |
Publisher | : Stanford University |
Total Pages | : 198 |
Release | : |
Genre | : |
ISBN | : |
Download Migration-Velocity Analysis using Image-Space Generalized Wavefields Book in PDF, ePub and Kindle
Author | : Armand Wirgin |
Publisher | : Springer |
Total Pages | : 312 |
Release | : 2014-05-04 |
Genre | : Science |
ISBN | : 3709124867 |
Download Wavefield Inversion Book in PDF, ePub and Kindle
This book provides an up-to-date presentation of a broad range of contemporary problems in inverse scattering involving acoustic, elastic and electromagnetic waves. Descriptions will be given of traditional (but still in use and subject to on-going improvements) and more recent methods for identifying either: a) the homogenized material parameters of (spatially) unbounded or bounded heterogeneous media, or b) the detailed composition (spatial distribution of the material parameters) of unbounded or bounded heterogeneous media, or c) the location, shape, orientation and material characteristics of an object embedded in a wellcharacterized homogeneous, homogenized or heterogeneous unbounded or bounded medium, by inversion of reflected, transmitted or scattered spatiotemporal recorded waveforms resulting from the propagation of probe radiation within the medium.
Author | : Andreas Fichtner |
Publisher | : Springer Science & Business Media |
Total Pages | : 352 |
Release | : 2010-11-16 |
Genre | : Science |
ISBN | : 3642158072 |
Download Full Seismic Waveform Modelling and Inversion Book in PDF, ePub and Kindle
Recent progress in numerical methods and computer science allows us today to simulate the propagation of seismic waves through realistically heterogeneous Earth models with unprecedented accuracy. Full waveform tomography is a tomographic technique that takes advantage of numerical solutions of the elastic wave equation. The accuracy of the numerical solutions and the exploitation of complete waveform information result in tomographic images that are both more realistic and better resolved. This book develops and describes state of the art methodologies covering all aspects of full waveform tomography including methods for the numerical solution of the elastic wave equation, the adjoint method, the design of objective functionals and optimisation schemes. It provides a variety of case studies on all scales from local to global based on a large number of examples involving real data. It is a comprehensive reference on full waveform tomography for advanced students, researchers and professionals.
Author | : Robert H. Stolt |
Publisher | : Cambridge University Press |
Total Pages | : 417 |
Release | : 2012-02-09 |
Genre | : Technology & Engineering |
ISBN | : 1139505289 |
Download Seismic Imaging and Inversion: Volume 1 Book in PDF, ePub and Kindle
Extracting information from seismic data requires knowledge of seismic wave propagation and reflection. The commonly used method involves solving linearly for a reflectivity at every point within the Earth, but this book follows an alternative approach which invokes inverse scattering theory. By developing the theory of seismic imaging from basic principles, the authors relate the different models of seismic propagation, reflection and imaging - thus providing links to reflectivity-based imaging on the one hand and to nonlinear seismic inversion on the other. The comprehensive and physically complete linear imaging foundation developed presents new results at the leading edge of seismic processing for target location and identification. This book serves as a fundamental guide to seismic imaging principles and algorithms and their foundation in inverse scattering theory, and is a valuable resource for working geoscientists, scientific programmers and theoretical physicists.
Author | : Claudio Guerra Cardoso |
Publisher | : |
Total Pages | : |
Release | : 2010 |
Genre | : |
ISBN | : |
Download Migration-velocity Analysis Using Image-space Generalized Wavefields Book in PDF, ePub and Kindle
An accurate depth-velocity model is the key for obtaining good quality and reliable depth images in areas of complex geology. In such areas, velocity-model definition should use methods that describe the complexity of wavefield propagation, such as focusing and defocusing, multiple arrivals, and frequency-dependent velocity sensitivity. Wave-equation tomography in the image space has the ability to handle these issues because it uses wavefields as carriers of information. However, its high cost and low flexibility for parametrizing the model space has prevented its routine industrial use. This thesis aims at overcoming those limitations by using new wavefields as carriers of information: the image-space generalized wavefields. These wavefields are synthesized by using a pre-stack generalization of the exploding-reflector model. Cost of wave-equation tomography in the image space is decreased because only a small number of image-space generalized wavefields are necessary to accurately describe the kinematics of velocity errors and because these wavefields can be easily used in a target-oriented way. Flexibility is naturally incorporated into wave-equation tomography in the image space by using these wavefields because their modeling have as the initial conditions some key selected reflectors, allowing a layer-based parametrization of the model space. To use the image-space generalized wavefields in wave-equation tomography in the image space, the method is extended from the shot-profile domain to the image-space generalized-sources domain. In this new domain, the velocity updates are very fast. Migration with the optimized velocity model provides good quality and reliable depth images, as can be seen in a 3D-field data example.
Author | : Gerard T. Schuster |
Publisher | : SEG Books |
Total Pages | : 377 |
Release | : 2017-07-01 |
Genre | : Science |
ISBN | : 156080341X |
Download Seismic Inversion Book in PDF, ePub and Kindle
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. Seismic Inversion will be of benefit 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. For those not familiar with the terminology and methods of seismic exploration, a brief introduction is provided. To truly understand the nuances of seismic inversion, we have to actively practice what we preach (or teach). Therefore, computational labs are provided for most of the chapters, and some field data labs are given as well.
Author | : Tijmen Jan Moser |
Publisher | : SEG Books |
Total Pages | : 823 |
Release | : 2016-06-30 |
Genre | : Science |
ISBN | : 1560803177 |
Download Seismic Diffraction Book in PDF, ePub and Kindle
The use of diffraction imaging to complement the seismic reflection method is rapidly gaining momentum in the oil and gas industry. As the industry moves toward exploiting smaller and more complex conventional reservoirs and extensive new unconventional resource plays, the application of the seismic diffraction method to image sub-wavelength features such as small-scale faults, fractures and stratigraphic pinchouts is expected to increase dramatically over the next few years. “Seismic Diffraction” covers seismic diffraction theory, modeling, observation, and imaging. Papers and discussion include an overview of seismic diffractions, including classic papers which introduced the potential of diffraction phenomena in seismic processing; papers on the forward modeling of seismic diffractions, with an emphasis on the theoretical principles; papers which describe techniques for diffraction mathematical modeling as well as laboratory experiments for the physical modeling of diffractions; key papers dealing with the observation of seismic diffractions, in near-surface-, reservoir-, as well as crustal studies; and key papers on diffraction imaging.
Author | : C.P.A. Wapenaar |
Publisher | : Elsevier |
Total Pages | : 485 |
Release | : 2014-04-14 |
Genre | : Science |
ISBN | : 1483291006 |
Download Elastic Wave Field Extrapolation Book in PDF, ePub and Kindle
Extrapolation of seismic waves from the earth's surface to any level in the subsurface plays an essential role in many advanced seismic processing schemes, such as migration, inverse scattering and redatuming. At present these schemes are based on the acoustic wave equation. This means not only that S-waves (shear waves) are ignored, but also that P-waves (compressional waves) are not handled correctly. In the seismic industry there is an important trend towards multi-component data acquisition. For processing of multi-component seismic data, ignoring S-waves can no longer be justified. Wave field extrapolation should therefore be based on the full elastic wave equation.In this book the authors review acoustic one-way extrapolation of P-waves and introduce elastic one-way extrapolation of P- and S-waves. They demonstrate that elastic extrapolation of multi-component data, decomposed into P- and S-waves, is essentially equivalent to acoustic extrapolation of P-waves. This has the important practical consequence that elastic processing of multi-component seismic data need not be significantly more complicated than acoustic processing of single-component seismic data. This is demonstrated in the final chapters, which deal with the application of wave field extrapolation in the redatuming process of single- and multi-component seismic data. Geophysicists, and anyone who is interested in a review of acoustic and elastic wave theory, will find this book useful. It is also a suitable textbook for graduate students and those following courses in elastic wave field extrapolation as each subject is introduced in a relatively simple manner using the scalar acoustic wave equation. In the chapters on elastic wave field extrapolation the formulation, whenever possible, is analogous to that used in the chapters on acoustic wave field extrapolation. The text is illustrated throughout and a bibliography and keyword index are provided.