This is the first book of its kind on seismic amplitude inversion in the context of reflection tomography. The aim of the monograph is to advocate the use of ray-amplitude data, separately or jointly with traveltime data, in reflection seismic tomography. The emphasis of seismic exploration is on imaging techniques, so that seismic section can be interpreted directly as a geological section. In contrast it is perhaps ironic that, in decades of industrial seismology, one major aspect of waveform data that potentially is easier to measure and analyse has generally been ignored. That is, the information content of seismic amplitudes. Perhaps the potential complexity has deterred most researchers from a more thorough investigation of the practical use of seismic amplitude data. The author of this volume presents an authoritative and detailed study of amplitude data, as used in conjunction with traveltime data, to provide better constraints on the variation of seismic wave speed in the subsurface. One of the fundamental problems in conventional reflection seismic tomography using only traveltime data is the possible ambiguity between the velocity variation and the reflector depth. The inclusion of amplitude data in the inversion may help to resolve this problem because the amplitudes and traveltimes are sensitive to different features of the subsurface model, and thereby provide more accurate information about the subsurface structure and the velocity distribution. An essential goal of this monograph is to make the amplitude inversion method work with real reflection seismic data.
Stepwise linear regression of a database of 177 Class III hydrocarbon prospect outcomes and associated descriptions of Direct Hydrocarbon Indicator (DHI) observations indicate that the seismic characteristics can be used to predict well outcomes with a success rate better than 74% for out of sample tests. The most important seismic characteristics are presence of a phase change at the down dip edge of the anomaly, down dip conformance of the anomaly to structure (fit to closure), lack of unexplained anomalies in the same stratigraphic interval in the area, down-dip extent of the anomaly consistent with sealing capacity, and presence of prospect analogues. AVO analysis and results consistent with rock physics trends are also found to be significant factors in success/failure analysis. As seal capacity is an often neglected factor, its high ranking in the stepwise regression has significant practical implications. The mean-squared prediction error and residuals for all of the predictions are within acceptable limits. This shows that there is a relationship between the characteristics and quality of the interpreted DHI anomalies and the prospect outcome.
A rich literature exists on computational methods based on wave equations for seismic imaging and earth-parameter estimation. Somewhat lost in the advance to progressively more sophisticated computational techniques are the intuitive ideas with roots that reach back to Hagedoorn and are based on ray theory, the geometry of data, and the geometry of wave propagation. In Seismic True-Amplitude Imaging (SEG Geophysical Developments Series No. 12), the authors describe their research of many years, demonstrating that those simple ideas also lead to a broad description of the structure of the earth's interior and the changes in medium parameters across reflectors. Demonstrations in the open literature of the efficacy of their methods abound. Now those ideas have been collected and reorganized. The book gives a pictorial presentation of the basic principles of Kirchhoff-type imaging and proceeds to a comprehensive treatment of its kinematic and dynamic aspects. The text is a valuable addition to the library of anyone interested in the theory and practices of seismic data processing for imaging and parameter estimation with all its attendant processes.
We continue exploring methodologies to improve earthquake-explosion discrimination using regional amplitude ratios such as P/S in a variety of frequency bands. Empirically we demonstrate that such ratios separate explosions from earthquakes using closely located pairs of earthquakes and explosions recorded on common, publicly available stations at test sites around the world (e.g. Nevada, Novaya Zemlya, Semipalatinsk, Lop Nor, India, Pakistan, and North Korea). We are also examining if there is any relationship between the observed P/S and the point source variability revealed by longer period full waveform modeling (e. g. Ford et al 2008). For example, regional waveform modeling shows strong tectonic release from the May 1998 India test, in contrast with very little tectonic release in the October 2006 North Korea test, but the P/S discrimination behavior appears similar in both events using the limited regional data available. While regional amplitude ratios such as P/S can separate events in close proximity, it is also empirically well known that path effects can greatly distort observed amplitudes and make earthquakes appear very explosion-like. Previously we have shown that the MDAC (Magnitude Distance Amplitude Correction, Walter and Taylor, 2001) technique can account for simple 1-D attenuation and geometrical spreading corrections, as well as magnitude and site effects. However in some regions 1-D path corrections are a poor approximation and we need to develop 2-D path corrections. Here we demonstrate a new 2-D attenuation tomography technique using the MDAC earthquake source model applied to a set of events and stations in both the Middle East and the Yellow Sea Korean Peninsula regions. We believe this new 2-D MDAC tomography has the potential to greatly improve earthquake-explosion discrimination, particularly in tectonically complex regions such as the Middle East. Monitoring the world for potential nuclear explosions requires characterizing seismic events and discriminating between natural and man-made seismic events, such as earthquakes and mining activities, and nuclear weapons testing. We continue developing, testing, and refining size-, distance-, and location-based regional seismic amplitude corrections to facilitate the comparison of all events that are recorded at a particular seismic station. These corrections, calibrated for each station, reduce amplitude measurement scatter and improve discrimination performance. We test the methods on well-known (ground truth) datasets in the U.S. and then apply them to the uncalibrated stations in Eurasia, Africa, and other regions of interest to improve underground nuclear test monitoring capability.
Author: Haruo Sato
Publisher: Springer Science & Business Media
Release Date: 2008-12-17
Seismic waves – generated both by natural earthquakes and by man-made sources – have produced an enormous amount of information about the Earth's interior. In classical seismology, the Earth is modeled as a sequence of uniform horizontal layers (or sperical shells) having different elastic properties and one determines these properties from travel times and dispersion of seismic waves. The Earth, however, is not made of horizontally uniform layers, and classic seismic methods can take large-scale inhomogeneities into account. Smaller-scale irregularities, on the other hand, require other methods. Observations of continuous wave trains that follow classic direct S waves, known as coda waves, have shown that there are heterogeneities of random size scattered randomly throughout the layers of the classic seismic model. This book focuses on recent developments in the area of seismic wave propagation and scattering through the randomly heterogeneous structure of the Earth, with emphasis on the lithosphere. The presentation combines information from many sources to present a coherent introduction to the theory of scattering in acoustic and elastic materials and includes analyses of observations using the theoretical methods developed.
Author: S.K. Upadhyay
Publisher: Springer Science & Business Media
Release Date: 2013-03-09
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.
The interest in seismic stratigraphic techniques to interpret reflection datasets is well established. The advent of sophisticated subsurface reservoir studies and 4D monitoring, for optimising the hydrocarbon production in existing fields, does 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 decades. Seismic profiles and 3D cubes form a vast and robust data source to unravel the structure of the subsurface. It gets nowadays exploited in ever greater detail. Larger offsets and velocity anisotropy effects give for instance access to more details on reservoir flow properties like fracture density, porosity and permeability distribution, Elastic inversion and modelling may tell something about the change in petrophysical parameters. Seismic investigations provide a vital tool for the delineation of subtle hydrocarbon traps. 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. The here presented modern geophysical techniques allow more accurate prediction of the changes in subsurface geology. Dynamics of sedimentary environments are discussed with its relation to global controling factors and a link is made to high-resolution sequence stratigraphy. ‘Seismic Stratigraphy Basin Analysis and Reservoir Characterisation’ summarizes basic seismic interpretation techniques and demonstrates the benefits of intergrated reservoir studies for hydrocarbon exploration. Topics are presented from a practical point of view and are supported by well-illustrated case histories. The reader (student as well as professional geophysicists, geologists and reservoir engineers) is taken from a basic level to more advanced study techniques. * Overview reflection seismic methods and its limitations. * Link between basic seismic stratigraphic principles and high resolution sequence stratigraphy. * Description of various techniques for seismic reservoir characterization and synthetic modelling. * Overview nversion techniques, AVO and seismic attributes analysis.
Seismic attributes play a key role in exploration and exploitation of hydrocarbons. In Seismic Attributes for Prospect Identification and Reservoir Characterization (SEG Geophysical Developments No. 11), Satinder Chopra and Kurt J. Marfurt introduce the physical basis, mathematical implementation, and geologic expression of modern volumetric attributes including coherence, dip/azimuth, curvature, amplitude gradients, seismic textures, and spectral decomposition. The authors demonstrate the importance of effective color display and sensitivity to seismic acquisition and processing. Examples from different basins illustrate the attribute expression of tectonic deformation, clastic depositional systems, carbonate depositional systems and diagenesis, drilling hazards, and reservoir characterization. The book is illustrated generously with color figures throughout. "Seismic Attributes" will appeal to seismic interpreters who want to extract more information from data; seismic processors and imagers who want to learn how their efforts impact subtle stratigraphic and fracture plays; sedimentologists, stratigraphers, and structural geologists who use large 3D seismic volumes to interpret their plays within a regional, basinwide context; and reservoir engineers whose work is based on detailed 3D reservoir models. Copublished with EAGE.
Author: N.A. Anstey
Publisher: Springer Science & Business Media
Release Date: 2012-12-06
This text was originally written for use with the videotape program of the same title. Numbered video cassettes correspond to the following chapters of the book: Tape Chapter(s) Tape Chapter(s) 1 1-2. 2. 1 11 3. 4 2 2. 2. 2-2. 3 12 3. 5. 1-3. 5. 2 3 2. 4 13 3. 5. 3 4 2. 5-2. 6 14 3. 5. 4-3. 6. 3 5 2. 7-2. 8 15 3. 7-3. 7. 2 6 3 16 3. 8-4 7 3. 1 17 4. 1 8 3. 2-3. 2. 1 18 4. 2-4. 4 9 3. 2. 2-3. 2. 3 19 5 10 3. 3 Complete information about the videotape program, Seismic Exploration for Sandstone Reservoirs may be obtained from: IHRDC, 137 Newbury St. , Boston, MA 02116, (617) 536-0202. Acknowledgements Thanks are expressed to the authors, companies and professional associations who have allowed the use of their material in the course. The author and publisher are grateful for permission to reproduce material whose copyright belongs as follows: Figures: 2. 4-3 (Widess) SEG; 2. 4-4 (Prescott) Continental Oil Company; 3-1 (Le Blanc) AAPG; 3-2 (MacKenzie) AAPG; 3. 1-1 Seiscom Delta; 3. 1-3 (Schramm et al. ) AAPG; 3. 1-4 (Lamer et al. ) Western Geophysical Company; 3. 2. 2-2 Prakla Seismos; 3. 2. 2-3 (Leung et al. ) Amoco Europe; 3. 2. 2-4 (Newman et al. ) S&A Geophysical; 3. 2. 3-2 Seiscom Delta; 3. 3-1 (Taner) Seiscom Delta; 3.
Author: Per Avseth
Publisher: Cambridge University Press
Release Date: 2010-06-10
Quantitative Seismic Interpretation demonstrates how rock physics can be applied to predict reservoir parameters, such as lithologies and pore fluids, from seismically derived attributes. The authors provide an integrated methodology and practical tools for quantitative interpretation, uncertainty assessment, and characterization of subsurface reservoirs using well-log and seismic data. They illustrate the advantages of these new methodologies, while providing advice about limitations of the methods and traditional pitfalls. This book is aimed at graduate students, academics and industry professionals working in the areas of petroleum geoscience and exploration seismology. It will also interest environmental geophysicists seeking a quantitative subsurface characterization from shallow seismic data. The book includes problem sets and a case-study, for which seismic and well-log data, and Matlab codes are provided on a website (http://www.cambridge.org/9780521816014). These resources will allow readers to gain a hands-on understanding of the methodologies.