Author: Rob Simm
Publisher: Cambridge University Press
Release Date: 2014-04-17
Seismic amplitudes yield key information on lithology and fluid fill, enabling interpretation of reservoir quality and likelihood of hydrocarbon presence. The modern seismic interpreter must be able to deploy a range of sophisticated geophysical techniques, such as seismic inversion, AVO (amplitude variation with offset), and rock physics modelling, as well as integrating information from other geophysical techniques and well data. This accessible, authoritative book provides a complete framework for seismic amplitude interpretation and analysis in a practical manner that allows easy application - independent of any commercial software products. Deriving from the authors' extensive industry expertise and experience of delivering practical courses on the subject, it guides the interpreter through each step, introducing techniques with practical observations and helping to evaluate interpretation confidence. Seismic Amplitude is an invaluable day-to-day tool for graduate students and industry professionals in geology, geophysics, petrophysics, reservoir engineering, and all subsurface disciplines making regular use of seismic data.
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.
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.
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.
Abstract: Magma is transported in brittle rock through dikes and sills. This movement may be accompanied by the release of seismic energy that can be tracked from the Earth's surface. Locating dikes and deciphering their dynamics is therefore of prime importance in understanding and potentially forecasting volcanic eruptions. The Seismic Amplitude Ratio Analysis (SARA) method aims to track melt propagation using the amplitudes recorded across a seismic network without picking the arrival times of individual earthquake phases. This study validates this methodology by comparing SARA locations (filtered between 2 and 16 Hz) with the earthquake locations (same frequency band) recorded during the 2014–2015 Bár ∂ arbunga‐Holuhraun dike intrusion and eruption in Iceland. Integrating both approaches also provides the opportunity to investigate the spatiotemporal characteristics of magma migration during the dike intrusion and ensuing eruption. During the intrusion SARA locations correspond remarkably well to the locations of earthquakes. Several exceptions are, however, observed. (1) A low‐frequency signal was possibly associated with a subglacial eruption on 23 August. (2) A systematic retreat of the seismicity was also observed to the back of each active segment during stalled phases and was associated with a larger spatial extent of the seismic energy source. This behavior may be controlled by the dike's shape and/or by dike inflation. (3) During the eruption SARA locations consistently focused at the eruptive site. (4) Tremor‐rich signal close to ice cauldrons occurred on 3 September. This study demonstrates the power of the SARA methodology, provided robust site amplification; Quality Factors and seismic velocities are available. Plain Language Summary: Locating earthquakes usually implies picking phase arrivals ( P and S waves). Another technique called Seismic Amplitude Ratio Analysis (SARA) was recently introduced to locate them only by using the amplitude recorded at different pairs of seismic stations. However, this technique was never proven to be true. This study shows that the earthquake locations derived by SARA compares remarkably well with the locations of 30, 000 seismic events triggered when magma migrated in the Icelandic crust prior to the 2014–2015 Holuhraun eruption. But the results also provide new insight into the magma dynamics that led to the largest eruption of the last two centuries in Europe. We show that ground vibration was continuously triggered during the 2 week period preceding the eruption when magma forced its way toward the eruption site but also during the eruption itself. Several intriguing features were observed including low‐frequency vibrations possibly associated with eruption below the ice, or large patches of seismic activity when the magma stopped propagating toward the eruption site. This methodology performs very well, provided some parameters are available, and allows to gain insights into the complex dynamics associated with magma movements. Key Points: This work provides a proof of concept of the Seismic Amplitude Ratio Analysis (SARA) Seismic energy continuously released even in the absence of earthquakes detected by traditional techniques Seismic observations during stalled phases are explained by changes in the dike shape and/or dike inflation.
Author: Haruo Sato
Publisher: Springer Science & Business Media
Release Date: 2012-01-28
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 spherical 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. The second edition especially includes new observational facts such as the spatial variation of medium inhomogeneities and the temporal change in scattering characteristics and recent theoretical developments in the envelope synthesis in random media for the last ten years. Mathematics is thoroughly rewritten for improving the readability. Written for advanced undergraduates or beginning graduate students of geophysics or planetary sciences, this book should also be of interest to civil engineers, seismologists, acoustical engineers, and others interested in wave propagation through inhomogeneous elastic media.
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.