Based on regional control, it is known that the section consists of sediments down to about 4 km. The reflection event at 6. The group of reflections between 8—10 s, which corresponds to a depth range of 25—35 km, represents a transition zone in the lower crust — most likely, the Moho discontinuity, itself.
Common-midpoint CMP recording is the most widely used seismic data acquisition technique. By providing redundancy, measured as the fold of coverage in the seismic experiment, it improves signal quality. Figure I-3 shows seismic data collected along the same traverse in with single-fold coverage and in with twelve-fold coverage. These two different vintages of data have been subjected to different treatments in processing; nevertheless, the fold of coverage has caused the most difference in the signal level of the final sections.
Seismic data processing strategies and results are strongly affected by field acquisition parameters. Additionally, surface conditions have a significant impact on the quality of data collected in the field. Part of the seismic section shown in Figure I-4 between midpoints A and B is over an area covered with karstic limestone.
Note the continuous reflections between 2 and 3 s outside the limestone-covered zone. These reflections abruptly disappear under the problem zone in the middle. The lack of events is not the result of a subsurface void of reflectors. Surface conditions also have an influence on how much energy from a given source type can penetrate into the subsurface. Figure I-5 shows a seismic section along a traverse over a karstic topography with a highly weathered near-surface.
In data acquisition, surface charges have been used to the right of midpoint A, and charges have been placed in holes to the left of midpoint A. In the absence of source coupling using surface charges, there is very little energy that can penetrate into the subsurface through the weathered near-surface layer.
As a result, note the lack of coherent reflections to the right of midpoint A. On the other hand, improved source coupling using downhole charges has resulted in better penetration of the energy into the subsurface in the remainder of the section.
Besides surface conditions, environmental and demographic restrictions can have a significant impact on field data quality. The part of the seismic section shown in Figure I-6 between midpoints A and B is through a village.
In the village, the vibroseis source was not operated with full power. Hence, not enough energy penetrated into the earth. Although surface conditions were similar along the entire line, the risk of property damage resulted in poor signal quality in the middle portion of the line.
Other factors, such as weather conditions, care taken during recording, and the condition of the recording equipment, also influence data quality. Almost always, seismic data are collected often in less-than-ideal conditions.
Hence, we can only hope to attenuate the noise and enhance the signal in processing to the extent allowed by the quality of the data acquisition. In addition to field acquisition parameters, seismic data processing results also depend on the techniques used in processing.
A conventional processing sequence almost always includes the three principal processes — deconvolution , CMP stacking , and migration. Sheriff, David C. Change Password. Old Password. New Password. Password Changed Successfully Your password has been changed.
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Request Username Can't sign in? Forgot your username? Enter your email address below and we will send you your username. Buy print edition Recommend to a librarian. Purchase Save for later Item saved, go to cart. In addition to the developments in all aspects of conventional processing, this two-volume set represents a comprehensive and complete coverage of the modern trends in the seismic industry-from time to depth, from 3-D to 4-D, from 4-D to 4-C, and from isotropy to anisotropy.
All of this book's content, except where otherwise noted including republished material , is licensed under a Creative Commons Attribution 3. Distribution or reproduction of this work in whole or in part commercially or noncommercially requires full attribution of the original publication, including its digital object identifier DOI. Derivatives of this work must carry the same license. O how sweet it is — Listening to the echos from the earth.
The seismic method has three principal applications: a Delineation of near-surface geology for engineering studies, and coal and mineral exploration within a depth of up to 1 km: The seismic method applied to the near-surface studies is known as engineering seismology.
Front Matter. Preview Abstract The front matter contains the title page, copyright page, dedication, table of contents, preface to the first edition, and the preface. The seismic method has three Fundamentals of Signal Processing. Preview Abstract 1. Residual statics corrections often are required for cess are critically examined via an extensive series of improving velocity estimation and stacking.
In a daily synthetic and real data examples. For experienced seismic explorationists, is a good length for the deconvolution operator? What this book should serve as a refresher and handy ref- should the prediction lag be? What should the de- erence. However, it is not just meant for the seismic sign gate for the operator be? How should the corre- analyst. Explorationists who would like to gain a prac- lation window be chosen in residual statics computa- tical background in seismic data processing without any tions?
Many more questions matical treatise on the main subjects is provided in the could be included in this list of questions. To help an- appendixes. I also appreciate his valuable recommenda- key the text into the word processor. I also thank everlasting encouragement. The second edition Concurrent with prestack imaging, we began to im- is the culmination of this continuous update over the age the subsurface also in depth to account for strong past ten years.
The updating process was based on ex- lateral velocity variations. I have also drawn an extensive and for earth modeling and imaging in depth. Using appro- demonstrative set of real-data examples from the nu- priate inversion methods, we derive a seismic represen- merous case studies that I conducted during the course tation of an earth model in depth, described by two sets of the update.
The power of 3-D visualization has given us seismic data analysis — processing, inversion, and inter- the ability to create an earth model in depth with the pretation of seismic data. Additionally, the rapid growth analysis during the past 15 years.
Additionally, terpretation. Techniques for multi- lineate the structural model of the subsurface, but we ple attenuation based on the Radon transform and wave also make use of the seismic amplitudes to infer the extrapolation have been successfully demonstrated on depositional model of the subsurface. The road ahead for exploration seismology includes Shortly after 3-D migration, we also began to image three main topics — 4-D seismic method, 4-C seismic the subsurface before stacking.
Such changes may be related to changes I is devoted to 2-D conventional processing based on in the seismic amplitudes from one 3-D survey to the the three principle processes — deconvolution, stack- next. Time-lapse 3-D seismic monitoring of reservoirs ing, and migration. Volume I is devoted to topics be- is referred to as the 4-D seismic method.
Potential applications of ing in depth, 4-D seismic method, 4-C seismic method, the 4-D seismic method include monitoring the spatial and anisotropy. Each chapter is accompanied by an ap- extent of the steam front following in-situ combustion pendix that includes a mathematical treatise of selected or steam injection used for thermal recovery, monitoring topics from the chapter itself. As such, practical aspects the spatial extent of the injected water front used for of seismic data analysis are treated within the chapters secondary recovery, imaging bypassed oil, determining themselves without the burden of the theoretical details.
By record- mology based on primarily the appendixes. If you are a research geophysicist using this recording and analysis is often referred to as the 4- book as a reference, you can study the practical aspects C seismic method. While the source of tation, mapping hydrocarbon saturation, and mapping this passion is indisputably my teacher and life-long oil-water contact. Most appropriately, I wish to express here my of reservoir rocks.
Seismic anisotropy often is associated heartful gratitudes to each of these individuals. For instance, in To begin with, I am deeply grateful to Steve Do- a vertically fractured limestone reservoir, velocity in the herty, my technical editor and life-long friend, for his fracture direction is lower than velocity in the direction incisive, meticulous, and prompt editing of this entire perpendicular to the plane of fracturing, giving rise to work.
Another directional variation of the text.
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