e-Books

In this book the main problems related to the construction of an Earth-Model are presented and discussed. The first three chapters are dedicated to the classical methods that can be used to build numerical models, in particular, the author proposes:
– some of the classical modeling techniques used in Computer Aided Design (CAD) to model surfaces and their inadequacy for modeling complex geological objects, in particular:
– classical interpolation techniques used to model surfaces;
– topological models used to describe the connections between surfaces and volumes;
– an overview of geomodeling methods dedicated to the discrete modeling of geological objects, in particular:
– the Discrete-Smooth-Interpolation method (DSI);
– meshing techniques to model surfaces and grids;
– a presentation of the classical ?Shared-Earth-Model? (SEM) paradigm consisting in a Structural-Model (SM) plus a Property-Model (PM): SEM = SM + PM
– a discussion concerning the problems raised by the (in) compatibility between the Structural-Model (SM) and the Property-Model (PM).

‘Permo-Triassic Sequence of the Arabian Plate’, edited by Michael Pöppelreiter, is based on the findings of an EAGE organized workshop held in Kuwait on the stratigraphy, reservoir and exploration techniques of the Arabian Khuff formation. The volume portrays the Khuff formation, which stretches across six countries, from an integrated petroleum- systems perspective: source, reservoir and seal across the platform from margin to open marine environments.
The special publication was written by 64 authors and co-authors, from 17 nations across three continents, affiliated to industry and academia. The Khuff is portrayed hierarchically from basin, play, environment, body and grain scale in 15 chapters on 400 pages with emphasis on 229 high-quality, full-colour figures.
The publication emphasizes the importance of subtle tectonics on all elements of the petroleum system. For those who want to find out more about the formation, the book has a contacts directory of Khuff specialists on different subject matters.

Despite its fundamental importance for acquiring an accurate picture of the subsurface, the topic of time-to-depth conversion on the basis of true propagation velocities has never been addressed in the form of a comprehensive, dedicated book. The present book has long been overdue for bridging this obvious gap in geoscience. Geophysicists proficient in data processing fully appreciate that depth imaging, despite the excellence achieved in data quality and lateral positioning, does not amount to true or accurate depth conversion. This is because modelling “velocities” in processing (described in the book as “pro-velocities”) can often be quite different from the actual propagation velocities.
The many forms of velocities, their interrelationships, their derivation, their assessment and the various factors that could affect their stability and accuracy, are all thoroughly covered. Common misconceptions are brought to notice. The main thrust is for the use of these velocities for time-todepth conversion. Extensive details of depth conversion procedures are established, together with velocity models, each to suit the various depth conversion situations arising in practice. Factors affecting depth conversion results and estimation of the associated uncertainty are extensively covered. Clarity and simplicity of presentation and practical applicability are a prime consideration. Demystifying some topics that are vague to a majority of geoscientists (e.g. anisotropy) also receives ample attention.
The book is written for the interpretation geophysicist working in exploration and development, for the seismic processor seeking a wider perspective on the quality of output and on the provision of the data to help the “frontline” geoscientist, for the geologist using geophysical methods as a tool at various levels of detail in the evaluation of the subsurface, and for the geoscientist at large.

Satellite radar data for surface deformation monitoring are gaining increasing attention, and not only within the oil and gas community. They provide a powerful tool for remotely measuring extremely small surface displacements over large areas and long periods of time, without requiring the installation of in-situ equipment. However, apart from remote sensing and radar specialists, only a relatively small number of geoscientists and engineers understand how a radar sensor orbiting the Earth at about 7 km/s from 700km above the Earth’s surface can actually measure ground displacements of a fraction of a centimetre.
This book provides a step-by-step introduction to satellite radar sensors, SAR imagery, SAR interferometry and advanced InSAR techniques. Rather than a tutorial for remote sensing specialists, the book starts from very basic concepts and explains in plain language the most important ideas related to SAR data processing and why geoscientists and engineers should take a vested interest in this new information source.

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.

Three case studies are included to demonstrate the applicability, workflow and limitations of this technology: a physical laboratory 3D experiment where fracture distributions are known, a Middle East fractured carbonate reservoir and a fractured tight gas reservoir. Our ultimate goal is to build 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.

The EAGE’s Education Tour (EET) offers a one-day course delivered by renowned geoscientists at various locations globally. Accompanied by a comprehensive course book, it provides members and others with access to the latest developments in key topics in the Geosciences. The Tour has been a great success since its launch in 2006.

The book presents the various seismic imaging methods currently in use in the Oil and Gas industry in a unified and almost equation-free approach. Guided step by step through each method well illustrated by figures and examples, the reader will discover differences between time and depth imaging, how they impact the quality of the seismic image, the distinction between Kirchhoff, Gaussian Beam and other Beam techniques, principles of ray-based tomography and how it may be used after wave-equation methods, in what sense two-way Reverse Time Migration differs from one-way Shot Point migration, what are the emerging routes for migration velocity analysis, what can we expect from Full Waveform Inversion and at what cost, how 3D and wide azimuth acquisition impact imaging, and answers to many other questions.

In this publication, Philippe Doyen reviews some of the most widely used workflows for constraining 3-D earth models with seismic data. They typically involve a sequential process where seismic data are first inverted to elastic properties. Inverted data are then depth-converted and transferred into the earth model framework, where the seismic attributes are used to guide the interpolation of reservoir properties between the wells.
Geostatistics provides a number of tools for this purpose, including generalized regression techniques such as cokriging and kriging with external drift, stochastic simulation with seismic constraints and geostatistical inversion. These techniques are reasonably well-established and their application can lead to significantly better constrained earth models. So what are the remaining challenges for seismic data integration in earth models? In particular, what are the main limitations or bottlenecks with current approaches that need to be addressed in order to make this integration more widely applicable? In the last few paragraphs, Philippe Doyen lists some of the future challenges and new directions in seismic earth modelling.

Tomographic imaging of seismic velocities is probably the most novel application of the seismic method to high resolution exploration and monitoring of the subsurface. It is a pleasure to make available a comprehensive state-of-the-art book giving an excellent overview of seismic tomography explaining the current status of the method, describing it and evaluating the possibilities and the potential for future developments.
The book covers a wide range of applications of seismic tomography in geotechnological and geoscientific investigations, in particular for engineering and exploration. The intent to be practical is well met with many field examples and problems, without neglecting the basic principles needed to understand the examples more deeply and to judge the quality of the imaging. A very comprehensive list of references to specific and general publications on the subject allows access to more detailed information.
Bodo Lehmann has succeeded very well in making seismic tomography understandable and useful to the geoscientific and geoengineering community and beyond. This is the most comprehensive book currently available on seismic tomography. It is suitable not only for professional geophysicists, geologists and engineers but also for study at the graduate level.

Velocities, Imaging, and Waveform Inversion - The evolution of characterizing the Earth’s subsurface is part of Ian Jones' EAGE Education Tour and will be a fusion of practical industrial elements, concentrating on the origin and nature of the geological complexities that give rise to imaging problems, as well as a physical (rather than mathematical) understanding of subsurface parameter estimation, and will also look at some possible future directions. The course is designed for: practising geoscientists who desire to better understand the principles and limitations of both current and emerging technologies involved in subsurface parameter estimation and imaging and geoscience students. Following this course, participants should ideally understand how contemporary velocity estimation methods work, and what approximations are involved in obtaining computationally tractable solutions.
In using sound waves to characterise the Earth’s subsurface, we can employ ray theory and/or wave theory, and both migration algorithms and parameter estimation schemes employ one or other of these theoretical descriptions. In this course, we will review the evolution of the industry’s approaches to building earth models via velocity estimation and imaging, outlining the evolution from ray tomography to full waveform inversion, and look towards the emerging possibilities for replacing imaging techniques with direct subsurface parameter inversion methods.
The approach will be mostly non-mathematical, concentrating on an intuitive understanding of the principles, demonstrating them via case histories, and will be divided into the following sections:
- Dealing with the near surface
- The effects of strong vertical velocity contrasts
- The effects of strong lateral velocity contrasts
- Waves versus rays - Model building using ray methods (tomography)
- Model building using wavefield extrapolation methods (FWI)
- Data examples and comparisons
- Future developments
The first three sections outline the nature of the problems we face when building images representing subsurface impedance contrasts, and the next three deal with the technology we deploy to address the problems. In addition, I have included three appendices to outline: the historical development of model building, anisotropy and pre-processing considerations for complex imaging. Several of the individual chapters build on a series of recent tutorial papers which I published in First Break. However, only the key points from these tutorial papers are included, so I refer readers to the original papers for more detail and/or a range of real data examples for each of their topics.
However, due to space and time constraints in the EET format, I have had to omit or limit coverage of various topics, including migration of multiples, Marchenko and inverse scattering series migration, joint migration-inversion, least-squares migration and uncertainty estimation.