Download or read book Waveform Inversion of Seismic Reflection Data Through Local Optimisation Methods written by Jonas Lindgren and published by . This book was released on 1992-01-01 with total page 132 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Estimation of Impedance Using Seismic Reflection Data Based on Transdimensional Inversion written by Sireesh Kumar Dadi and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Deterministic seismic inversion can obtain optimal results when there is a linear relationship between data and model parameters during local optimization (single optimum solution). For nonlinear geophysical problems and in the presence of multiple local minima for a cost function, global optimization techniques are necessary to characterize the global minimum solution. Stochastic, model-based seismic inversion is a widely used global optimization technique and Markov Chain Monte Carlo (MCMC) method is a natural choice to sample model parameters during the random walk. In this dissertation, I apply a sampling technique called reversible jump Markov Chain Monte Carlo (rjMCMC) to traverse the model space. A key property of this approach is that it automatically changes the layer thicknesses and number of layers, thereby predicting the optimum number of model parameters during inversion. The method applies Bayesian inversion, with rjMCMC sampling, so that it also quantifies the uncertainty in model parameters based on an ensemble of models. I apply Bayesian inversion with rjMCMC sampling for two applications. In the first application, I define upscaling velocity logs as an inversion problem to obtain optimal models and quantify uncertainty of upscaled models at the well location. The upscaled velocity at the well locations can be subsequently used to stabilize velocity inversion during Full waveform Inversion (FWI) for seismic imaging purposes. In the second application, I perform post-stack seismic inversion to obtain shallow impedance structure of the TAMU and Ori volcanoes at the Shatsky Rise oceanic plateau. Since impedance is a rock property, it is used to discriminate basalt rock types, which gives insight into the late-stage evolution of both the volcanoes. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/152595
Download or read book Optimization methods for 2 D pre stack migration velocity estimation written by Michael Anthony Jervis and published by . This book was released on 1993 with total page 370 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Full Seismic Waveform Modelling and Inversion written by Andreas Fichtner and published by Springer Science & Business Media. This book was released on 2010-11-16 with total page 352 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Full Waveform Inversion Using Simultaneous Encoded Sources Based on First and Second order Optimization Methods written by Amsalu Y. Anagaw and published by . This book was released on 2014 with total page 152 pages. Available in PDF, EPUB and Kindle. Book excerpt: Full waveform inversion (FWI) is an emerging seismic technology engine for estimating subsurface model parameters such as velocity, density and attenuation through local minimization of an objective function. The minimization problem is often performed iteratively via gradient-based method that is based on the first-order derivatives of the objective function. One of the major obstacles of FWI that hinders its practical applications for estimating subsurface model parameters for large scale problems is its huge computational demand for performing many forward modeling for multiple sources. One way to reduce the overall cost of waveform inversion is by adopting a simultaneous source strategy. In other words, multiple sources are simultaneously fired to simulate super-shot gathers and thereby reduce the number of seismic modeling simulations that are performed during the inversion. However, the use of simultaneous sources introduces cross-talk artifacts that arise from the interference among the sources that constitute a super-shot. In this thesis, we study and extend the practical applications of the second-order optimization methods in the framework of simultaneous sources. First, we examined the effect of model parameterizations on velocity model building using Newton-based optimization methods. Three model parameterizations for the acoustic FWI were investigated. These include velocity, slowness and slowness squared. We then analyze the influence of different simultaneous multi-frequency selection strategies on cross-talk artifacts. Our analysis focuses on a multiscale frequency-domain FWI algorithm that is implemented with simultaneous sources that are randomly encoded with a source-encoding function. In the multiscale conventional FWI inversion strategies, a finite set of discrete frequencies will be selected and the inversion is carried out sequentially from low to high frequency data components. We examine six frequency selection strategies and test the performance of the algorithm with encoded datasets. Numerical tests show that high fidelity results can be attained by inverting partially overlapped groups of temporal frequencies. In order to mitigate cross-talk artifacts during the numerical inversion, a new encoding is generated at every iteration. We also found that high resolution images can be obtained by re-sampling new source positions and new encoding functions at every iteration of the FWI algorithm. Finally, we present a full Newton FWI algorithm and its application in the presence of high amplitude multi-reflected waves that are generated by strong velocity contrast and/or from free surface reflections.
Download or read book Implementing Efficient Global Optimization Methods in Full Waveform Inversion written by Debanjan Datta and published by . This book was released on 2017 with total page 410 pages. Available in PDF, EPUB and Kindle. Book excerpt: Full Waveform Inversion (FWI) is slowly becoming the standard for velocity estimation from seismic data. It uses the full wave equation to estimate high resolution models capable of recovering finer details compared to traditional methods like tomography. FWI is constructed as a least squares optimization problem that iteratively updates an initial model until the misfit between modeled and observed data are within a pre-specified tolerance. The local nature of FWI makes it sensitive to the choice of starting model which has to be in the global minimum trough of the misfit function. If the starting model lies outside the global minimum trough, FWI converges to a local minima giving an incorrect estimation of subsurface properties. In this thesis, I eliminate the sensitivity to the starting model when performing FWI. This is done by recasting FWI into a global optimization problem using a combination of sparse parameterization methods. The starting model is generated by a global optimization method that is not sensitive to the starting model. The result from the global optimization method is then used as a starting model for conventional FWI using a dense set of parameters. In chapter 2, I apply global optimization with a sparse parameterization technique for 2D models using a combination of interfaces and velocities. Chapter 3 extends the sparse parameterization for salt bodies using ellipse sets and level-set methods. Lastly, chapter 4 extends sparse parameterization in three dimensions to perform FWI without a starting guess. I demonstrate that the proposed approaches are not sensitive to the source of starting model and discuss some sources of uncertainty. Another issue that prevents implementation of FWI on a regular basis is its computational cost. Expensive forward evaluations need to be performed multiple times across several iterations to obtain the final model. It is of particular significance in 3D where in addition to posing a computational cost problem, it also creates a data reversal problem when computing the gradient. I propose two approaches to reduce the computational cost of forward modeling and gradient computation in the time and frequency domains. The frequency domain approach discussed in chapter 5 exploits the contribution of unchanging zones in an inversion workflow to be reused over subsequent iterations of FWI. The final chapter discusses how to run a gradient computation on GPUs using faster interconnect and on-node memory. I provide a template to apply it to a general adjoint problem with specific example on FWI. I obtain a 20-40% and 82-207% improvement in runtimes in the frequency and time domain, respectively, using the proposed methods
Download or read book Shared Earth Modeling written by John R. Fanchi and published by Elsevier. This book was released on 2002-08-25 with total page 319 pages. Available in PDF, EPUB and Kindle. Book excerpt: Shared Earth Modeling introduces the reader to the processes and concepts needed to develop shared earth models. Shared earth modeling is a cutting-edge methodology that offers a synthesis of modeling paradigms to the geoscientist and petroleum engineer to increase reservoir output and profitability and decrease guesswork. Topics range from geology, petrophysics, and geophysics to reservoir engineering, reservoir simulation, and reservoir management.Shared Earth Modeling is a technique for combining the efforts of reservoir engineers, geophysicists, and petroleum geologists to create a simulation of a reservoir. Reservoir engineers, geophysicists, and petroleum geologists can create separate simulations of a reservoir that vary depending on the technology each scientist is using. Shared earth modeling allows these scientists to consolidate their findings and create an integrated simulation. This gives a more realistic picture of what the reservoir actually looks like, and thus can drastically cut the costs of drilling and time spent mapping the reservoir. First comprehensive publication about Shared Earth Modeling Details cutting edge methodology that provides integrated reservoir simulations
Download or read book Study on Rupture Process by Waveform Inversion Using Simulated Annealing and Simulation of Broadband Ground Motions written by 芝良昭 and published by Contentsworks Inc.. This book was released on 2004 with total page 63 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Introduction to Derivative Free Optimization written by Andrew R. Conn and published by SIAM. This book was released on 2009-04-16 with total page 276 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first contemporary comprehensive treatment of optimization without derivatives. This text explains how sampling and model techniques are used in derivative-free methods and how they are designed to solve optimization problems. It is designed to be readily accessible to both researchers and those with a modest background in computational mathematics.
Download or read book Exact Waveform Inversion of Seismic Reflection Data written by Nina Diane Bregman and published by . This book was released on 1982 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Scattering Two Volume Set written by E. R. Pike and published by Elsevier. This book was released on 2001-10-09 with total page 1831 pages. Available in PDF, EPUB and Kindle. Book excerpt: Scattering is the collision of two objects that results in a change of trajectory and energy. For example, in particle physics, such as electrons, photons, or neutrons are "scattered off" of a target specimen, resulting in a different energy and direction. In the field of electromagnetism, scattering is the random diffusion of electromagnetic radiation from air masses is an aid in the long-range sending of radio signals over geographic obstacles such as mountains. This type of scattering, applied to the field of acoustics, is the spreading of sound in many directions due to irregularities in the transmission medium. Volume I of Scattering will be devoted to basic theoretical ideas, approximation methods, numerical techniques and mathematical modeling. Volume II will be concerned with basic experimental techniques, technological practices, and comparisons with relevant theoretical work including seismology, medical applications, meteorological phenomena and astronomy. This reference will be used by researchers and graduate students in physics, applied physics, biophysics, chemical physics, medical physics, acoustics, geosciences, optics, mathematics, and engineering. This is the first encyclopedic-range work on the topic of scattering theory in quantum mechanics, elastodynamics, acoustics, and electromagnetics. It serves as a comprehensive interdisciplinary presentation of scattering and inverse scattering theory and applications in a wide range of scientific fields, with an emphasis, and details, up-to-date developments. Scattering also places an emphasis on the problems that are still in active current research. The first interdisciplinary reference source on scattering to gather all world expertise in this technique Covers the major aspects of scattering in a common language, helping to widening the knowledge of researchers across disciplines The list of editors, associate editors and contributors reads like an international Who's Who in the interdisciplinary field of scattering
Download or read book Conference on Inverse Scattering Theory and Application written by J. Bee Bednar and published by SIAM. This book was released on 1983-01-01 with total page 310 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Doing Physics Doing Gender written by Anna T. Danielsson and published by Anna Teresia Danielsson. This book was released on 2009-06-15 with total page 284 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Global Optimization Methods in Geophysical Inversion written by Mrinal K. Sen and published by Cambridge University Press. This book was released on 2013-02-21 with total page 303 pages. Available in PDF, EPUB and Kindle. Book excerpt: An up-to-date overview of global optimization methods used to formulate and interpret geophysical observations, for researchers, graduate students and professionals.
Download or read book Offset dependent Reflectivity written by John P. Castagna and published by SEG Books. This book was released on 1993 with total page 356 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recognizing the need for education and further research in AVO, the editors have compiled an all-encompassing treatment of this versatile technology. In addition to providing a general introduction to the subject and a review of the current state of the art, this unique volume provides useful reference materials and data plus original contributions at the leading edge of AVO technologies.
Download or read book Seismic Reflection Processing written by S.K. Upadhyay and published by Springer Science & Business Media. This book was released on 2013-03-09 with total page 641 pages. Available in PDF, EPUB and Kindle. Book excerpt: Seismic Reflection Processing coherently presents the physical concepts, mathematical details and methodology for optimizing results of reservoir modelling, under conditions of isotropy and anisotropy. The most common form of anisotropy - transverse isotropy - is dealt with in detail. Besides, practical aspects in reservoir engineering - such as interval isotropic or anisotropic properties of layered media; identifying lithology, pore-fluid types and saturation; and determining crack/fracture-orientations and density - form the core of discussions. This book incorporates significant new developments in isotropic and anisotropic reflection processing, while organizing them to improve the interpretation of seismic reflection data and optimizing the modeling of hydrocarbon reservoirs. It is written primarily as a reference and tutorial for graduate/postgraduate students and research workers in geophysics.
Download or read book Inverse Problems Design and Optimization vol 1 written by and published by Editora E-papers. This book was released on with total page 365 pages. Available in PDF, EPUB and Kindle. Book excerpt:
