Download or read book Seismic Forward Modeling of Fractures and Fractured Medium Inversion written by Xiaoqin Cui and published by Springer. This book was released on 2017-06-09 with total page 170 pages. Available in PDF, EPUB and Kindle. Book excerpt: This detailed book systematically investigates subsurface geological fractures using rock mechanics, geology, and geophysics. Based on geological fracture mechanisms and fracture boundary conditions, it presents new finite-difference equations for the simulation of seismic wave responses to geological fractures, and proposes innovative AVO inversion equations for the accurate estimation of the rock properties of the fractured medium. It employs schematics, snapshots, color images and charts to demonstrate the mechanical characteristics of the fractures, the seismic wave-field response to the fractures, the seismic data attributes of the fractures and the rock properties of the fractures obtained via inversion. It provides a new methodology for enhancing geological fracture detection technology and for the accurate delineation of fractured reservoirs that ultimately benefits reservoir and mining engineers, geologists and geophysicists in terms of optimizing reservoir recovery, well performance and mining safety.
Download or read book Seismic Wave Theory written by Edward S. Krebes and published by Cambridge University Press. This book was released on 2019-03-28 with total page 367 pages. Available in PDF, EPUB and Kindle. Book excerpt: Concise textbook on seismic wave theory, with detailed derivations of formulas, clear explanations of topics, exercises, and selected answers.
Download or read book Seismic Wave Theory written by Edward S. Krebes and published by Cambridge University Press. This book was released on 2019-03-28 with total page 367 pages. Available in PDF, EPUB and Kindle. Book excerpt: Perfect for senior undergraduates and first-year graduate students in geophysics, physics, mathematics, geology and engineering, this book is devoted exclusively to seismic wave theory. The result is an invaluable teaching tool, with its detailed derivations of formulas, clear explanations of topics, exercises along with selected answers, and an additional set of exercises with derived answers on the book's website. Some highlights of the text include: a review of vector calculus and Fourier transforms and an introduction to tensors, which prepare readers for the chapters to come; and a detailed discussion on computing reflection and transmission coefficients, a topic of wide interest in the field; a discussion in later chapters of plane waves in anisotropic and anelastic media, which serves as a useful introduction to these two areas of current research in geophysics. Students will learn to understand seismic wave theory through the book's clear and concise pedagogy.
Download or read book Cost Effective Strategies for Problems in Computational Geophysics written by Janaki Vamaraju and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first part of my thesis focuses on seismic modeling in fractured media. Several recent developments in finite elements such as usage of high degree polynomials to approximate the wavefield, diagonalization of mass matrices to be inverted through mass lumping techniques and usage of high order time-stepping schemes, have made these methods (along with their classical advantages) more attractive when compared to the finite difference methods (FDM). Discontinuous Galerkin finite element method (DGM) and spectral element method (SEM) have particularly attracted researchers in the field of numerical wave propagation. SEM uses continuous basis functions, which do not allow for discontinuities in the displacement field. Hence it can be used to simulate wave propagation only in non-fractured media. On the other hand, DGM allows for discontinuities in the displacement field to simulate fractures or faults but with a significant increase in computation cost and memory requirement. Here, I formulate and analyze two new, improved finite element techniques (FEM) for the numerical solution of elastic wave propagation in fractured and non-fractured media. Enriched Galerkin (EGM) and hybrid Galerkin (HGM) formulations are proposed for solving elastic wave propagation that has advantages similar to those of DGM but with a computational cost comparable to that of SEM. EGM uses the same bilinear form as DGM, and discontinuous piecewise constants or bilinear functions enrich the continuous Galerkin finite element spaces. EGM satisfies local equilibrium while reducing the degrees of freedom in DGM formulations. HGM employs DGM in areas containing fractures and SEM in regions without fractures. The coupling between the domains at the interfaces is satisfied through interface conditions. The degree of reduction in computation time depends primarily on the density of fractures in the medium. I apply these methods to model wave propagation in 2D/3D fractured media and validate their efficiency with numerical examples. Fractured reservoirs are more complicated due to the presence of fractures and pores. Biot’s fundamental theory on wave propagation in fluid-saturated porous media is still well accepted and forms the basis of this work. To examine the effects of fluid-filled cracks and fractures, I next propose to combine poroelasticity with the linear slip theory for simulating wave propagation in fractured porous media. This study provides an equivalent anisotropic medium model for the description of porous rock with fractures in the seismic frequency band. I solve Biot’s poroelastic wave equations using a velocity-stress staggered grid finite difference algorithm. Through numerical examples, I show that fractures and pores strongly influence wave propagation, induce anisotropy, and poroelastic behavior in wavefields. I also validate the presence of two compressional waves as predicted by Biot’s theory along with the converted waves due to faults. Compared to elastic methods, this approach provides a considerably concise and more accurate model for fractured reservoirs. The second part of my thesis centers on developing cost-effective solutions for seismic migrations and anisotropic moveout corrections. Least-squares migration (LSM) is a linearized inversion problem that iteratively minimizes a misfit functional as a function of the model perturbation. The success of the inversion largely depends on our ability to handle large systems of equations given the massive computation costs. I propose a suite of unsupervised machine learning (ML) approaches that leverage the existing physics-based models and machine learning optimizers to achieve more accurate and cheaper solutions. First, I use a special kind of unsupervised recurrent neural network and its variant, Hopfield neural networks, and the Boltzmann machine, to solve the problems of Kirchhoff and post-stack reverse time migrations. Physics-based forward models can be used to derive the weights and biases of the neural network. The optimal configuration of the neural network after training corresponds to the minimum energy of the network and thus gives the reflectivity solution of the migration problem. I next implement a fast image-domain target-oriented least-squares reverse time migration (LSRTM) workflow using a conjugate Hopfield network. The method computes a low-cost target-oriented Hessian matrix using plane-wave Green’s functions. I recover a more accurate image in the presence of a truncated Hessian matrix. I further implement pre-stack LSRTM in a deep learning framework and adopt various machine learning optimizers to achieve more accurate and cheaper solutions than conventional methods. Using a time-domain formulation, I show that mini-batch gradients can reduce the computation cost by using a subset of total shots for each iteration. Mini-batches not only reduce source cross-talk but are also less memory intensive. Combining mini-batch gradients with Adam optimizer and Huber loss function can improve the efficiency of pre-stack LSRTM. I demonstrate high accuracy predictions on complex synthetic models that can generate noisy data. Finally, I develop a Hough transform neural network based technique for normal moveout correction in vertically transverse isotropic (VTI) media. This technique offers advantages when compared to the time and computational costs required in a conventional anisotropic normal moveout correction. Using a Hough transform based neural network, I simultaneously fit all the non-hyperbolic reflection moveout curves using intermediate to long offsets. I apply the network to synthetic VTI datasets and demonstrate the practical feasibility of anisotropic moveout correction that is independent of travel-time picking and velocity analysis
Download or read book Azimuthal P wave AVA Inversion for Fracture Orientation and Density written by Keyao Xia and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis studies the numerical seismic modeling of a simulated fractured medium to analyze variations of seismic reflection amplitudes with incident and azimuthal angles (AVAZ). The intent is to extract the information about the fracture orientation and intensity of a fractured medium. The effective compliance tensor for a fractured medium can be written as the sum of the compliance tensor of the unfractured background rock and the compliance tensor for the set of aligned fractures. Based on the assumption of rotationally invariant fracture sets, two fracture compliances the normal and tangential compliance are required to specify the fracture compliance tensor. The stiffness tensor can be attained by inverting the compliance tensor. The P-wave reflection coefficients for arbitrary anisotropic media are obtained by two methods (Chattopadhyay, 2004; Schoenberg and Protazio, 1992). Rüger's linear approximation can accurately estimate the exact reflection coefficients and hence it is widely used in the linear inversion. Analysis is applied in the decision to choose between the incident angle and the average angle for Rüger's linear approximation. Linear AVAZ inversions, based on singular value decomposition (SVD), and non-linear AVAZ inversion, based on generalized linear inversion (GLI), for fracture orientation and HTI anisotropy parameters, were applied on P-wave reflection coefficients with variable incident angle and azimuth. However, 90° ambiguity in the estimation of the fracture orientation always exists. Sensitivity analysis of the inversion results, including S/N ratio, maximum incident angle used, and error propagation, confirms the accuracy of the amplitude analysis.
Download or read book Numerical Modeling of Seismic Responses from Fractured Reservoirs by the Grid characteristic Method written by Leviant Vladimir and published by . This book was released on 2019 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt: Using direct seismic responses of fractures and fracture zones to obtain location and characteristic information is a promising direction of investigation. This book addresses properties of fractured media seismic waves by describing, modeling, and analyzing responses from discrete fractured media, and proposes a methodology for direct detection.
Download or read book Seismic Fracture Characterization written by Enru Liu and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: During the last three decades, seismic anisotropy has evolved from a purely academic research topic into applications in the mainstream of applied geophysics. Today, nobody doubts that the earth is anisotropic and most (if not all) hydrocarbon reservoirs are anisotropic. Since shale accounts for 70% of sedimentary basins and fractures exist in all reservoirs, seismic anisotropy may be even more extensive than we think. Taking anisotropy into account in seismic processing has improved the quality of seismic images, even though it makes seismic processing more challenging since additional parameters are needed. At the same time, fracture characterization using the concept of seismic anisotropy has added value in reservoir characterization, reservoir management, and has increased recovery and optimized well locations. This book and the associated course provide an introduction to the fundamental concepts of seismic fracture characterization by introducing seismic anisotropy, equivalent-medium representation theories of fractured rock and methodologies for extracting fracture parameters from seismic data. We focus on practical applications using extensive field data examples. Includes cast studies demonstrating the applicability, workflow and limitations of this technologyContains physical laboratory 3D experiments where fracture distributions are known, a Middle East fractured carbonate reservoir and a fractured tight gas reservoir. Builds discrete fracture network models incorporating all data. These models should not only be geologically consistent but also geophysically and geomechanically consistent, so that the models can be used to forecast the behaviour and performance of fractured reservoirs.
Download or read book Seismic Exploration of Hydrocarbons in Heterogeneous Reservoirs written by Jing Ba and published by Elsevier. This book was released on 2014-05-02 with total page 375 pages. Available in PDF, EPUB and Kindle. Book excerpt: Seismic Exploration of Hydrocarbons in Heterogeneous Reservoirs: New Theories, Methods and Applications is based on the field research conducted over the past decade by an authoring team of five of the world’s leading geoscientists. In recent years, the exploration targets of world's oil companies have become more complex. The direct detection of hydrocarbons based on seismic wave data in heterogeneous oil/gas reservoirs has become a hot spot in the research of applied and exploration geophysics. The relevant theories, approaches and applications, which the authors have worked on for years and have established mature technical processes for industrial application, are of significant meaning to the further study and practice of engineers, researchers and students in related area. Authored by a team of geophysicists in industry and academia with a range of field, instruction, and research experience in hydrocarbon exploration Nearly 200 figures, photographs, and illustrations aid in the understanding of the fundamental concepts and techniques Presents the latest research in wave propagation theory, unconventional resources, experimental study, multi-component seismic processing and imaging, rock physics modeling and quantitative seismic interpretation Sophisticated approach to research systematically forms an industrial work flow for geoscience and engineering practice
Download or read book Seismic Fracture Characterization written by Enru Liu and published by Academic Press. This book was released on 2013-12-06 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: During the last three decades, seismic anisotropy has evolved from a purely academic research topic into applications in the mainstream of applied geophysics. Today, nobody doubts that the earth is anisotropic and most (if not all) hydrocarbon reservoirs are anisotropic. Since shale accounts for 70% of sedimentary basins and fractures exist in all reservoirs, seismic anisotropy may be even more extensive than we think. Taking anisotropy into account in seismic processing has improved the quality of seismic images, even though it makes seismic processing more challenging since additional parameters are needed. At the same time, fracture characterization using the concept of seismic anisotropy has added value in reservoir characterization, reservoir management, and has increased recovery and optimized well locations. This book and the associated course provide an introduction to the fundamental concepts of seismic fracture characterization by introducing seismic anisotropy, equivalent-medium representation theories of fractured rock and methodologies for extracting fracture parameters from seismic data. We focus on practical applications using extensive field data examples. Includes cast studies demonstrating the applicability, workflow and limitations of this technology Contains physical laboratory 3D experiments where fracture distributions are known, a Middle East fractured carbonate reservoir and a fractured tight gas reservoir. Builds discrete fracture network models incorporating all data. These models should not only be geologically consistent but also geophysically and geomechanically consistent, so that the models can be used to forecast the behaviour and performance of fractured reservoirs.
Download or read book The Integration of Seismic Anisotropy and Reservoir Performance Data for Characterization of Naturally Fractured Reservoirs Using Discrete Feature Network Models written by Robert A. Will and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation presents the development of a method for quantitative integration of seismic (elastic) anisotropy attributes with reservoir performance data as an aid in characterization of systems of natural fractures in hydrocarbon reservoirs. This new method incorporates stochastic Discrete Feature Network (DFN) fracture modeling techniques, DFN model based fracture system hydraulic property and elastic anisotropy modeling, and non-linear inversion techniques, to achieve numerical integration of production data and seismic attributes for iterative refinement of initial trend and fracture intensity estimates. Although DFN modeling, flow simulation, and elastic anisotropy modeling are in themselves not new technologies, this dissertation represents the first known attempt to integrate advanced models for production performance and elastic anisotropy in fractured reservoirs using a rigorous mathematical inversion. The following new developments are presented: · Forward modeling and sensitivity analysis of the upscaled hydraulic properties of realistic DFN fracture models through use of effective permeability modeling techniques. · Forward modeling and sensitivity analysis of azimuthally variant seismic attributes based on the same DFN models. · Development of a combined production and seismic data objective function and computation of sensitivity coefficients. · Iterative model-based non-linear inversion of DFN fracture model trend and intensity through minimization of the combined objective function. This new technique is demonstrated on synthetic models with single and multiple fracture sets as well as differing background (host) reservoir hydraulic and elastic properties. Results on these synthetic control models show that, given a well conditioned initial DFN model and good quality field production and seismic observations, the integration procedure results in convergence of both fracture trend and intensity in models with both single and multiple fracture sets. Tests show that for a single fracture set convergence is accelerated when the combined objective function is used as compared to a similar technique using only production data in the objective function. Tests performed on multiple fracture sets show that, without the addition of seismic anisotropy, the model fails to converge. These tests validate the importance of the new process for use in more realistic reservoir models.
Download or read book Numerical Investigation of Seismic Wave Propagation in Fracture Systems written by Weidong Yi and published by . This book was released on 1999 with total page 380 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Static Conceptual Fracture Modeling written by Ronald A. Nelson and published by John Wiley & Sons. This book was released on 2019-11-25 with total page 201 pages. Available in PDF, EPUB and Kindle. Book excerpt: Modelling of flow in naturally fractured reservoirs is quickly becoming mandatory in all phases of oil and gas exploration and production. Creation of a Static Conceptual Fracture Model (SCFM) is needed as input to create flow simulations for today and for prediction of flow into the future. Unfortunately, the computer modelers tasked with constructing the gridded fracture model are often not well versed in natural fracture characterization and are often forced to make quick decisions as to the input required by the software used to create these models. Static Conceptual Fracture Modelling: Preparing for Simulation and Development describes all the fracture and reservoir parameters needed to create the fracture database for effective modelling and how to generate the data and parameter distributions. The material covered in this volume highlights not only natural fracture system quantification and formatting, but also describes best practices for managing technical teams charged with creating the SCFM. This book will become a must on the shelf for all reservoir modelers.
Download or read book Understanding the Micro to Macro Behaviour of Rock fluid Systems written by Richard Paul Shaw and published by Geological Society of London. This book was released on 2005 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding how fluids flow through though rocks is very important in a number of fields. Almost all of the world's oil and gas are produced from underground reservoirs. Knowledge of how they got where they are, what keeps them there and how they migrate through the rock is very important in the search for new resources, as well as for maximising the extraction of as much of the contained oil/gas as possible. Some contributors to this volume have been trying to understand real rocks in real situations and others have been working on computer models and laboratory simulations. Put together, these approaches have yielded very useful results, many of which are discussed in this volume.
Download or read book Forward Modeling and Interpretation of Multicomponent Seismic Data for Fracture Characterization Weyburn Field Saskatchewan written by Micah Daniel Reasnor and published by . This book was released on 2001 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Seismic Signatures and Analysis of Reflection Data in Anisotropic Media written by I. Tsvankin and published by Elsevier. This book was released on 2005-06-13 with total page 472 pages. Available in PDF, EPUB and Kindle. Book excerpt: Following the breakthrough in the last decade in identifying the key parameters for time and depth imaging in anisotropic media and developing practical methodologies for estimating them from seismic data, Seismic Signatures and Analysis of Reflection Data in Anisotropic Media primarily focuses on the far reaching exploration benefits of anisotropic processing. This volume provides the first comprehensive description of reflection seismic signatures and processing methods in anisotropic media. It identifies the key parameters for time and depth imaging in transversely isotropic media and describes practical methodologies for estimating them from seismic data. Also, it contains a thorough discussion of the important issues of uniqueness and stability of seismic velocity analysis in the presence of anisotropy. The book contains a complete description of anisotropic imaging methods, from the theoretical background to algorithms to implementation issues. Numerous applications to synthetic and field data illustrate the improvements achieved by the anisotropic processing and the possibility of using the estimated anisotropic parameters in lithology discrimination. Focuses on the far reaching exploration benefits of anisotropic processing First comprehensive description of reflection seismic signatures and processing methods in anisotropic media
Download or read book Rock Fractures and Fluid Flow written by National Research Council and published by National Academies Press. This book was released on 1996-08-27 with total page 568 pages. Available in PDF, EPUB and Kindle. Book excerpt: Scientific understanding of fluid flow in rock fracturesâ€"a process underlying contemporary earth science problems from the search for petroleum to the controversy over nuclear waste storageâ€"has grown significantly in the past 20 years. This volume presents a comprehensive report on the state of the field, with an interdisciplinary viewpoint, case studies of fracture sites, illustrations, conclusions, and research recommendations. The book addresses these questions: How can fractures that are significant hydraulic conductors be identified, located, and characterized? How do flow and transport occur in fracture systems? How can changes in fracture systems be predicted and controlled? Among other topics, the committee provides a geomechanical understanding of fracture formation, reviews methods for detecting subsurface fractures, and looks at the use of hydraulic and tracer tests to investigate fluid flow. The volume examines the state of conceptual and mathematical modeling, and it provides a useful framework for understanding the complexity of fracture changes that occur during fluid pumping and other engineering practices. With a practical and multidisciplinary outlook, this volume will be welcomed by geologists, petroleum geologists, geoengineers, geophysicists, hydrologists, researchers, educators and students in these fields, and public officials involved in geological projects.
Download or read book Theoretical And Computational Acoustics 2005 With Cd rom Proceedings Of The 7th International Conference Ictca 2005 written by Alexandra Tolstoy and published by World Scientific. This book was released on 2006-10-16 with total page 230 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume represents the latest advances in the field of theoretical and computational acoustics. The coverage includes results in the areas of underwater acoustics, seismics, scattering, inversion, genetic algorithms, reverberation, IFEM, Radon transforms, wavelet statistics, PE modeling, and Gaussian beams.
