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74th EAGE Conference and Exhibition - Workshops
- Conference date: 04 Jun 2012 - 07 Jun 2012
- Location: Copenhagen, Denmark
- ISBN: 978-90-73834-28-6
- Published: 04 July 2012
121 - 140 of 156 results
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Shallow Shear Wave Reflection Seismic on Firn and Ice – Insights, Challanges, and Opportunities From a Small Scale Experiment at Colle Gnifetti
Authors Ulrich Polom, C. Hofstede, A. Diez and O. EisenIn the summer season 2010, a small shallow reflection seismic experiment was carried out on the overburden firn and ice cover of the Colle Gnifetti, Monte Rosa group, Swiss/Italian Alps. This site is widely used for method testing, since the physical properties of ice are similar to polar regions. The whole experiment was designed to explore the scope of the shallow high-resolution vibroseis method for seismic targets of the firn and ice mass of nearly 60 m thickness. A special part of the experiment was the exploration of vibratory shear wave reflection seismic capabilities in such an environment, which was never done before. The small ELVIS vibrator system was used to generate seismic shear waves received by common planted horizontal geophones in a SH-SH (source and receivers arranged both perpendicular to the profiling direction) configuration on two profiles, arranged as a cross setup. The resulting seismic sections of both profiles clearly show the boundary from ice to rock (evaluated by ice coring in 2005), the structure dip and also deeper events within the underlaying rock up to 150 m in depth. Seismic velocities within the ice overburden were used to derive elastic parameters combined with the density function derived from the ice coring. The results of this experiment show promising new prospects for the vibratory shear wave reflection method on glaciers, firn, and ice.
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SH-wave Seismic Reflection Land Streamer Measurements to Map Very Shallow Sand Deposits
Authors Roger Wisn, Anders Almholt, Fredrik W. G. Olsen and Rune JrgensenWith the purpose of providing a detailed sedimentary geological model, as basis for improving groundwater pumping, a SH-wave reflection seismic survey was performed along a railway ramp of the great belt tunnel in Denmark. The survey provided a high resolution image of the very shallow subsurface and the SH reflection result was the primary source for the geological interpretations. Refraction seismic analysis of P-wave reflection records, surface wave measurements and VSP measurements in two boreholes were also carried out. Together with the SH reflection result and available borehole data these results were used to create a detailed geological model.
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Delineation of Detailed Structure in Holocene Unconsolidated Sediments using S-wave Type Land Streamer
More LessHigh-resolution shallow seismic reflection surveying using SH-wave type Land Streamer was conducted in the Tokyo Metropolitan area, where more than 25 million inhabitants concentrate in small but highly developed region of 3,500 square km. While seismic reflection surveys have been frequently conducted in the area to delineate relatively deep geologic structure as concealed active fault surveys, shallow reflection surveys have been exceptional due to the difficulty in surveying at such a high land-use area disturbed by high amplitude traffic and industrial noises. In contrast, the Land Streamer makes it easy to set a survey line and acquire high quality data even in urban area owing to its short array length along with appropriate coupling with paved surface through a metallic baseplate. We adopted it for the field surveys conducted in the Tokyo Metropolitan area to clarify the detailed structure in a buried valley filled with Holocene unconsolidated soft sediments, and to characterize them based on the S-wave velocity and other physical properties. A set of survey lines were allotted to transect across the buried valley, and the survey successfully delineated the near-surface sedimentary structure in the buried valley.
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Near-surface and Near-seabed S-waves from P-wave Sources
Authors James Gaiser and Richard VermMost shear-wave (S-wave) surveys in exploration seismology are acquired with compressional-wave (P-wave) sources. These are primarily for the purpose of recording P to S converted-wave (PS-wave) reflections to image deep oil and gas targets. Essential for processing, is to have a good model of Swave properties in the overburden and near surface. These properties include not only velocities and statics, but also the presence of S-wave birefringence (splitting) in azimuthally anisotropic media. In addition to PS-waves, pure mode shear-waves (SS-waves) are excited by P-wave sources due to the elastic nature of the near surface and these can aid in velocity model building. The purpose of this presentation is to examine several applications of SS-waves and PS-waves to characterize S-wave properties of the overburden using SS-wave modes from land and marine surveys. Synthetic seismic data from an HTI medium is used to demonstrate that fast and slow SS-waves can be recovered. Also in the marine environment, S-wave resolution is typically very high near the seabed, and can provide accurate S-wave statics and velocities for prestack depth migration (PSDM). An interferometry example shows that SS-waves can be retrieved from OBC data, and a PSDM example illustrates the high resolution that can be achieved with PS-wave data.
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S-wave Velocity from P-wave Reflection Data: The Role of Surface Waves
Authors Valentina Socco and Daniele BoieroHigh resolution seismic reflection surveys provide images of subsurface S-wave structures and are therefore a powerful tool for engineering problems. When SH seismic reflection cannot be gathered, shallow S-wave velocity models can be also obtained from surface wave data analysis. Surface waves (either acquired on purpose or extracted from P-wave seismic reflection gathers) can be considered a useful complement or an alternative to seismic reflection for engineering characterization of shallow layers.
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Dynamic Statics – Improving Seismic Image on a 3D-9C Survey
More LessApplication of innovative Dynamic Statics approach to solving and decoupling statics and velocity allowed for improved seismic image of PP component (pure mode P-wave), SS component (pure mode S-wave). Dynamic Statics algorithm computes statics corrections as pure time shifts on reflected waves and does not require velocity model and first break picking. Converted PS image (C-wave) was obtained automatically and was used as a QC by taking P-wave statics and velocity solution for the source component and S-wave statics and velocity for upgoing (receiver) component. Conventional velocity and first break based statics solution delivered lower quality results on this 3D-9C dataset, characterized by complex near-surface conditions, and C-wave image has never been obtained.
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SeaSeis:A Simple Open-source Seismic Data Processing System
More LessSeaSeis is a seismic data processing system that I developed over the past six years, and which has been distributed as open-source software for about three years. I believe the system is easy to use and easy to add new modules to, which are the two main objectives I had in mind when seriously starting to write it. "Ease of use" is obviously subjective, but ease to write and bind new modules into should be possible to judge more objectively. The main appeal of SeaSeis may be for researchers/developers who want to use it as a platform to quickly implement and test newly developed algorithms, but it may also appeal to quite a different type of users: Since SeaSeis provides broad functionality facilitating production processing, such as master flow generation and logging, a small processing company may find it useful to use it to supplement any other available (licensed) systems. In my dreams (and who says these never come true?), SeaSeis will at some point be combined with the strengths and functionality of other opensource processing systems, to form one fully capable system.
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Comparison of Open Source Seismic Processing Systems
More LessOpen software is a part of our daily lives, ranging from the operating systems used to manage large computer clusters to phone apps that monitor data usage. Such software is written and maintained by programmers willing to distribute their work freely for the sake of contributing to the community as a whole. Seismic processing software is no different and consequently draws upon and suffers from the same strengths and weaknesses as other open source software. As can be expected, there is no single free seismic package that provides all of the functionality that is available in open source form. In this talk, I will compare and contrast the major open source seismic processing packages available today in terms of their approach, functionality, ease of use and acceptance. I will also discuss some of the smaller, less known tools that are freely available.
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Parallel I/O and Computing in JavaSeis
By Chuck MosherJavaSeis is an Open Source project that provides infrastructure for parallel I/O and computation for seismic processing and imaging applications using the Java programming language. JavaSeis is not a seismic processing system, but rather a set of object-oriented classes and methods for building geophysical software applications. To date, the most extensive usage of JavaSeis has been with the SeisSpace seismic processing system from Landmark Graphics Corporation, a subsidiary of Halliburton. The JavaSeis project is hosted by SourceForge, a web-based repository for open source projects. JavaSeis is based on a long history of parallel computing algorithms, dating from the late 1970’s, when parallel computing first began to emerge as an important component of High Performance Computing (HPC). This history provides many of the unique features of JavaSeis, where a significant number of optimized parallel computing algorithms now reside. These features have been selected and tested through repeated application of a wide variety of parallel computing ideas to production processing and imaging problems in the geophysical industry. This history also has allowed the construction of a parallel computing model that performs very well on both shared memory and distributed memory computing hardware, allowing users to construct algorithms without tying their application to a specific hardware platform.
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GeBR:A Free Seismic Processing Interface
More LessThere are many programs for processing seismic data that are freely available and widespread, for example Seismic Un*x, Madagascar, FreeUSP, and SEPlib, among others. All these packages consist of packages of command-line-oriented programs that are designed to be used in sequence; the data conceptually flow in a pipeline through one program after another. Each program is generally controlled by its own set of command-line options. To take full advantage of such a toolkit, the user must have considerable knowledge beyond general geophysical expertise: shell scripting, process submission and management, and batch queue processing, to name a few. While these skills are useful, they should not be a requirement for seismic data processing. A suitable graphical user interface could take care of these computational details, allowing the user to focus on the central problem of processing seismic data. This is particularly important during training courses, where the limited duration of the does not leave time for learning skills that are not essential to the material being taught. A graphical user interface may also boost the uptake of a new program, by making it more accessible to users and allowing its easy integration with other programs available within the same interface. These principles have guided the development of GBR, a graphical user interface to control commandline programs for seismic processing. It permits users to build complex processing flows from predefined modules known as menus. Menus describing new programs can be easily added to the interface, extending its capabilities. GBR is also designed to be simple, in the sense that a couple of hours is enough to introduce the core features of the interface, to allow the user to start working with the seismic data.
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BotoSeis: An Interactive Interface for Seismic Processing with Seismic Unix
Authors German Garabito, Williams Garabito, Joao C. R and Gabriel AlmeidaDespite the Seismic Unix (SU) be the most famous open-source package for seismic processing is still a challenge to use it, specially for inexperienced users. Usually the SU package is used from a command line and using complicated shell scripts. In order to obtain a simple, flexible and robust way to work with the SU package, we present a graphical user interface, called BotoSeis, written in the Java programming language. BotoSeis is an interactive environment to create and manage projects, lines and flowcharts for seismic data processing. It is also possible to add new SU programs or edit any already included programs by an interactive way and without knowledge about any programming language. In the BotoSeis also it is possible to include programs of other packages as MADAGASCAR and proprietary programs. The BotoSeis project also has as objective to develop interactive tools for data visualization, velocity analysis, f-k filtering, muting and others. Currently, it has been developed the botoView for data visualization and the botoVelan for velocity analysis.
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Enhancing Geophysical Data Analysis with Open-source Software
Authors James I. Selvage, C. Jones and H. MacintyreWe demonstrate the software solutions that have enabled geoscientists, without previous software development experience, to experiment with their ideas and develop promising ideas into software solutions. This has involved the use and integration of several pieces of open-source software which together provide a solution to enhance geophysical data analysis whilst providing flexibility to be able to collaborate with third parties. We use software from a wider range of disciplines than just geosciences to take advantage of advances in other disciplines.
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Open Mobile Geocomputing
By Matt HallMobile touch-screen computers—smartphones and tablets—are more powerful, and much more fun to use, than the computers I met at school, university, and even in my first job in 1997. I believe these machines are the most important development in geo-computing since the proliferation of Linux workstations starting about eight years ago. Geoscientists should be especially excited because here, finally, is the possibility of the tactile, high-fidelity, three-dimensional display we’ve all dreamt of since seeing Minority Report in 2002. And you can buy one for less than $400. Open source software and mobile technology have an uncomfortable relationship. Given that both of the major mobile operating systems, Apple’s iOS and Google Android OS, have Unix-like foundations, there is surprisingly little mobile open source software. Sure, Android itself is open source, but an ironic upshot of this is that device resellers are imprinting themselves strongly on the firmware. This often results in limiting consumer choice, locking them in to unwanted relationships. But openness is not just about open source. Even if we don’t wish to publish all our code in this new, fragile, marginal market, we can help each other build more powerful tools as scientific software spreads to mobile platforms: 1. We can promote open standards and data models; 2. We can share and publish code fragments whenever we can; 3. We can design and document rich application programming interfaces; 4. We can design tools around powerful web-based services that we can reach from anywhere.
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Processing and Attribute Analysis of Low-frequency Blackfoot Data
Authors Akshay Gulati and Marcus WilsonThis paper examines the utility of Seismic Unix for processing and attribute analysis of low frequency seismic data. The data were acquired in July 1995 by the Consortium for Research in Elastic Wave and Exploration Seismology (CREWES) in Blackfoot, Alberta. The data are processed using Seismic Unix and the resulting migrated seismic section is compared to the results of previous processing done by a contractor. The quality of the migrated seismic section processed using Seismic Unix is comparable to the one done previously using commercial software. An exact comparison is not done because the two processing flows differ due to availability of advanced processing modules in open source software. After processing, instantaneous seismic attributes are computed, which help with interpretation and can be used as parameters for quality assurance of the final processing results.
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Open Data Library with Open Software Scripts
More LessThe open seismic data library provides data and processing scripts for research, software testing, demonstrations, and user training. There are data sets to support various efforts such as 2D, 3D, land, marine, random noise, multiples, and sampling. Public domain data sets are supplemented with scripts that provide detailed processing sequences and parameters that can be used with or without modification. The gateway the library is at the SEG wiki site, http://wiki.seg.org/index.php/Main_Page where you search for the term “open data”. For each data set the wiki provides meta data like a general overview, images, suggested use, geographic location, and links to seismic data and scripts. This library should accelerate testing and validation of new seismic research, especially at universities and small companies that do not have large data archives and processing groups.
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Processing of Seismic Reflection Data Using Matlab
Authors Abdullatif A Al- Shuhail and Wail A. MousaDue to the global demand for more energy while the less number of students interested to join sciences, particularly, Earth sciences, we thought of attracting more students from Electrical Engineering especially those interested in digital signal processing to the field of seismic data processing by writing our book on processing seismic reflection data using a very popular software them called MATLABTM. The step-by-step demo of the full reflection seismic data processing workflow using a complete real seismic data set places itself as a very useful feature of the book. This is especially true when students are performing their projects, and when professors and researchers are testing their new developed algorithms in MATLABTM for processing seismic data. The book provides the very basic seismic and signal processing theory required for each chapter and shows how to process the data from raw field records to a final image of the subsurface all using MATLAB. The MATLABTM codes and seismic data can be downloaded at: http://www.morganclaypool.com/page/mousa.
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An Open-source Real Time Data Model and Database
More LessThis paper describes and demonstrates an open-source high-performance real-time data model and database system designed to meet the challenges facing the oil and gas industry in managing large volumes of time-critical data. We will review the shortcomings of existing solutions and make the case for a significant change in data management technology and architecture, followed by the demonstration of an initial implementation.
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BP's Experience with Open-source Software and Open Datasets
More LessBP has had a long history of sharing the kernels of their inhouse processing packages with the wider geophysical community, in particular "FreeUSP" and "FreeDDS" via the website "freeusp.org". These packages have allowed BP to proselytize their approach to how to organize seismic data and process it. That is useful, because BP can more conveniently share algorithms with contractors who have adopted the packages or had their own software methodology influenced by them. These contractors can then use the algorithms to process data to BP's specifications.
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A Course in Geophysical Imaging Processing Using Seismic Unix
More LessFor the past 6 years, the Department of Geophysics at the Colorado School of Mines (CSM)has used the CWP/SU: Seismic Un*x (SU) package to give students a practical hands-on introduction to many of the varied issues of seismic data processing. The students start with a raw 2D seismic line (Mobil line 12 from Keys and Foster, 1998) and are introduced in a step by step manner to the processing procedures that take the data from raw shot gathers to a final depth or time-migrated image. Issues such as velocity analysis, deconvolution, wavelet shaping, multiple suppression, and velocity model building are covered. The final project requires the students to reprocess the data, making their own choices of techniques to produce a final migrated image, and to summarize their work in a professional-style poster presentation.
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SEPlib
By Robert ClappSEPlib is one of the oldest open source seismic processing software packages, dating back to the 1980s (and 1970s for its graphic routines). Its primary focus has always been the programmer, offering flexibility and performance often at the cost of simplicity. This trade off can be seen in the variety of languages it is written in/supports (C, C++, Fortran, java, and python). For performance intensive applications, it supports OpenMP and Cuda libraries/programs. In addition, it has libraries that automatically parallelize data-parallel applications on clusters. One of its most attractive features is its visualization capabilities. It includes vplot for 2-D graphics along with a multi-dimensional cube viewer with hooks to enable interactive processing.
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