Understanding Seismic Anisotropy in Exploration and Exploitation


Book Description

All rock masses are seismically anisotropic, but we generally ignore this in our seismic acquisition, processing, and interpretation. The anisotropy nonetheless does affect our data, in ways that limit the effectiveness with which we can use it, as long as we ignore it. This book, produced for use with the fifth SEG/EAGE Distinguished Instructor Short Course, helps us understand why this inconsistency between reality and practice has been so successful in the past and why it will be less successful in the future as we acquire better seismic data (especially including vector seismic data) and correspondingly higher expectations of it. This book helps us understand how we can modify our practice to more fully realize the potential inherent in our data through algorithms which recognize the fact of seismic anisotropy.







Understanding Seismic Anisotropy in Exploration and Exploitation, Second Edition


Book Description

Understanding Seismic Anisotropy in Exploration and Exploitation (second edition) by Leon Thomsen is designed to show you how to recognize the effects of anisotropy in your data and to provide you with the intuitive concepts that you will need to analyze it. Since its original publication in 2002, seismic anisotropy has become a mainstream topic in exploration geophysics. With the emergence of the shale resource play, the issues of seismic anisotropy have become central, because all shales are seismically anisotropic, whether fractured or not. With the advent of wide-azimuth surveying, it has become apparent that most rocks are azimuthally anisotropic, with P-wave velocities and P-AVO gradients varying with source-receiver azimuth. What this means is that analysis of such data with narrow-azimuth algorithms and concepts will necessarily fail to get the most out of this expensively acquired data. The issues include not only seismic wave propagation, but also seismic rock physics. Isotropic concepts including velocity, Young’s modulus, and Poisson’s ratio have no place in the discussion of anisotropic rocks, unless qualified in some directional way (e.g., vertical Young’s modulus). Likewise, fluid substitution in anisotropic rocks, using the isotropic Biot/Gassmann formula, leads to formal errors, because the bulk modulus does not appear, in a natural way, within the anisotropic P-wave velocity. This updated edition is now current as of 2014.




Quantitative Analysis of Geopressure for Geoscientists and Engineers


Book Description

Geopressure, or pore pressure in subsurface rock formations impacts hydrocarbon resource estimation, drilling, and drilling safety in operations. This book provides a comprehensive overview of geopressure analysis bringing together rock physics, seismic technology, quantitative basin modeling and geomechanics. It provides a fundamental physical and geological basis for understanding geopressure by explaining the coupled mechanical and thermal processes. It also brings together state-of-the-art tools and technologies for analysis and detection of geopressure, along with the associated uncertainty. Prediction and detection of shallow geohazards and gas hydrates is also discussed and field examples are used to illustrate how models can be practically applied. With supplementary MATLAB® codes and exercises available online, this is an ideal resource for students, researchers and industry professionals in geoscience and petroleum engineering looking to understand and analyse subsurface formation pressure.




3C Seismic and VSP: Converted waves and vector wavefield applications


Book Description

3C seismic applications provide enhanced rock property characterization of the reservoir that can complement P-wave methods. Continued interest in converted P- to S-waves (PS-waves) and vertical seismic profiles (VSPs) has resulted in the steady development of advanced vector wavefield techniques. PS-wave images along with VSP data can be used to help P-wave interpretation of structure in gas obscured zones, of elastic and fluid properties for lithology discrimination from S-wave impedance and density inversion in unconventional reservoirs, and of fracture characterization and stress monitoring from S-wave birefringence (splitting) analysis. The book, which accompanies the 2016 SEG Distinguished Instructor Short Course, presents an overview of 3C seismic theory and practical application: from fundamentals of PS-waves and VSPs, through to acquisition and processing including interpretation techniques. The emphasis is on unique aspects of vector wavefields, anisotropy, and the important relationships that unify S-waves and P-waves. Various applications and case studies demonstrate image benefits from PS-waves, elastic properties and fluid discrimination from joint inversion of amplitude variations with offset/angle (AVO/A), and VSP methods for anisotropic velocity model building and improved reservoir imaging. The book will be of interest to geophysicists, geologists, and engineers, especially those involved with or considering the use of AVO/A inversion, fracture/stress characterization analyses, or interpretation in gas-obscured reservoirs.




Anisotropy and Microseismics: Theory and Practice


Book Description

Downhole microseismic monitoring of stimulation and production of unconventional reservoirs has resulted in renewed industry interest in seismic anisotropy. This occurred not only because anisotropy of hydrocarbon-bearing shales is among the strongest in rocks but also because downhole microseismics shifts the focus from the standard exploration of P-waves to shear waves. The consequences of the difference in wave type are profound for geophysicists because everyone involved - from theoreticians to developers and users of microseismic data-processing software - must be aware of shear-wave splitting, singularities, and multivalued wavefronts, which have been largely irrelevant for P-waves propagating in relatively simple geologic settings. Anisotropy and Microseismics leads readers on a path of discovery of rarely examined wave phenomena and their possible usage. Most of the chapters begin by formulating a question, followed by explanations of what is exciting about it, where the mystery might lie, and what could be the potential value of answering the question. Importantly, the findings entail useful applications, as showcased by the unmistakably practical flavor of the chapters on microseismic event location, moment tensor inversion, and imaging. As an investigation of microseismic methodologies and techniques is conducted, it often yields unexpected results.




Elements of Seismic Dispersion


Book Description

Demonstrates how spectral decomposition and time-frequency methods have led to improved understanding and use of nonlinear harmonics, near-surface guided waves, layer-induced anisotropy, velocity dispersion and attenuation, interference, and Biot reflection. The discussion includes examples, figures, and literature references for further study.




Concepts and Applications in 3D Seismic Imaging


Book Description

Providing a broad and intuitive understanding of seismic-imaging concepts and methods to enable geoscientists to make appropriate decisions during acquisition, processing, imaging, and interpretation, this book shows trends in imaging research and encourages the adoption of new technologies to facilitate the optimal use of these images.




Seismic Stratigraphy and Depositional Facies Models


Book Description

The 2e of Seismic Stratigraphy and Depositional Facies Models summarizes basic seismic interpretation techniques and demonstrates the benefits of integrated reservoir studies for hydrocarbon exploration. Topics are presented from a practical point of view and are supported by well-illustrated case histories. The reader is taken from a basic level to more advanced study techniques. The presented modern geophysical techniques allow more accurate prediction of the changes in subsurface geology. Dynamics of sedimentary environments are discussed their relation to global controling factors, and a link is made to high-resolution sequence stratigraphy. The interest in seismic stratigraphic techniques to interpret reflection datasets is well established. The advent of sophisticated subsurface reservoir studies and 4D monitoring for optimizing the hydrocarbon production in existing fields demonstrate the importance of the 3D seismic methodology. The added value of reflection seismics to the petroleum industry has clearly been proven over the last few decades. Seismic profiles and 3D cubes form a vast and robust data source to unravel the structure of the subsurface. Larger offsets and velocity anisotropy effects give access to more details on reservoir flow properties like fracture density, porosity and permeability distribution. Elastic inversion and modeling may tell something about the change in petrophysical parameters. Seismic investigations provide a vital tool for the delineation of subtle hydrocarbon traps, and they are the basis for understanding the regional basin framework and the stratigraphic subdivision. Seismic stratigraphy combines two very different scales of observation: the seismic and well control. The systematic approach applied in seismic stratigraphy explains why many workers are using the principles to evaluate their seismic observations. - Discusses the link between seismic stratigraphic principles and sequence stratigraphy - Provides techniques for seismic reservoir characterization as well as well control - Analyzes inversion, AVO and seismic attributes




Rock Quality, Seismic Velocity, Attenuation and Anisotropy


Book Description

Seismic measurements take many forms, and appear to have a universal role in the Earth Sciences. They are the means for most easily and economically interpreting what lies beneath the visible surface. There are huge economic rewards and losses to be made when interpreting the shallow crust or subsurface more, or less accurately, as the case may be.