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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
101 - 150 of 156 results
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Geothermal Exploration – Ensuring an Optimized Utilization of Geothermal Energy in Low-enthalpy Sedimentary Settings
Authors Ben Norden, Sven Fuchs, Simon Weides, Inga Moeck and Andrea FrsterAn adequate comprehensive understanding of the subsurface geology is a pre-requisite for a precise planning and successful operating of geothermal applications and reduces the financial risks considerably. An exploration concept is needed which is tailored for the geological setting to be evaluated and the level of exploration performed prior to the geothermal exploration. We present examples from ongoing geothermal exploration projects encompassing, for example, studies on the geological structure, including the stress field, on the hydraulic and thermal properties of geological formations, and on the temperature prognoses for target reservoirs.
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Improved Inversion of Needle Probe Data for the Determination of Rock Thermal Properties
Authors Thue S. Bording, Sren Bom Nielsen and Niels BallingHeat flow, thermal conductivity and thermal diffusivity are essential properties in subsurface temperature modelling. We present initial results of a novel inversion approach for laboratory measurements of rock thermal conductivity and thermal diffusivity by the needle probe method. Instead of analytical expressions, we use a numerical finite element procedure for the forward temperature response. A Markov Chain Monte Carlo Metropolis Hastings inversion procedure produces estimates of rock thermal parameters with uncertainties.
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The Thermal Properties of the Subsurface – Key Parameters for Geothermal Energy Utilization
Authors Ben Norden, Thue S. Bording and Niels BallingOften the investigation of petrophysical properties is far behind the capabilities of sophisticated modelling techniques applied in basin and geothermal modelling and for which these data serve as an input. Therefore, more in-depth investigations especially of thermal properties are requested. We evaluate different methods and devices for measuring rock thermal properties including thermal conductivity and thermal diffusivity and will compare the results to assure a high quality of these important key parameters.
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Porosity and Permeability Depth Trends, Examples from the Danish Upper Triassic−Upper Jurassic Gassum Formation
ty-depth and permeability-depth trends, established for all cored intervals of the Gassum Formation. The porosity-depth and permeability-depth trends represent sandstones alteration during burial due to mechanical compaction and diagenesis. The focus of this study is on the Gassum Formation, which has the largest potential and is the main target for planned geothermal wells in Denmark, as it is widely distributed and generally occurs within the depth interval of 800-3000 m, thereby reaching sufficient high temperatures and still assumed to maintain the required porosity and permeability. The Gassum Formation occurs with thicknesses of 50–150 m in central and distal areas of the Danish part of the Norwegian−Danish Basin, thickening locally in association with salt structures and major faults (up to 300 m in the Sorgenfrei−Tornquist Zone) and thinning or being absent on the structural highs, such as the Skagerrak−Kattegat Platform and the Ringkøbing−Fyn High (Fig. 1). The Gassum Formation consists of shoreface, fluvial, estuarine, lacustrine, lagoonal and marine facies (Nielsen 2003).
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Deep Saline Pre-Rhaetian Triassic Aquifers in the Hllviken Halfgraben, Stratigraphy, Distribution, Petrology and Petrophysical Properties with Respect to Their Geothermal Potential
Authors Mikael Erlstrm and Sofie LindstrmThe pre-Rhaetian Triassic sequence in the Hllviken Halfgraben contains several sandstone layers, which have been investigated concerning their potential as geothermal aquifers. Two geothermal projects managed by E.ON Sverige AB, DONG (Danish Oil and Natural Gas) and HGS (Hovedstadens Geotermiske Samarbejde) resulted in the early 2000s in the completion of four deep wells in Copenhagen and Malm. The wells penetrate an up to 700 m thick pre-Rhaetian Triassic sequence at depths between 1800 m and 2650 m. The geological information from these wells and data from 15 older wells and one cored borehole constitute the main database in this study. The incentive has been the need for a comprehensive characterization of the Triassic aquifers regarding their distribution, lateral extension and petrophysical properties as to assess their geothermal potential on a regional scale.
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Geothermal Energy Production Assessment from Premature Reservoir Evaluation
Authors Carsten M. Nielsen and Lars KristensenAssessment of the geothermal energy production potential, in an early decision stage of a development project, is subjected to great uncertainty due to the often sparse data coverage. By using all available data i.e. wireline logs, core analysis data and seismic interpretations to construct a preliminary geological model for the area of interest, the basis for decision is strengthen. The geological model forms the basis for subsequent reservoir simulation, where the uncertainty in water flow rates from the various input parameters can be quantified. Different production strategies can be examined and optimized. Furthermore, any identified faults or geological baffles potentially constraining fluid flow may be incorporated and evaluated. The present paper illustrates the construction and use of a subsurface model to address uncertainties in early decision making for geothermal energy production projects.
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Regional Geothermal 3D Modeling in Denmark
Authors Sren E. Poulsen, Niels Balling, Thue S. Bording and Sren Bom NielsenWe present first results of a 3D model of the subsurface temperature in Denmark. Updated temperatures are contoured for the Gassum formation which is currently utilized for geothermal energy production. The Gassum formation of Upper Triassic/Lower Jurassic age is present in most of Denmark with sufficient net sand thickness and temperatures between 50oC and 80oC in large areas. This makes this formation of particular interest for further geothermal exploration. The regional geothermal model is expected to aid decision makers in future prospecting of geothermal resources in Denmark.
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Risking Seismic Amplitude Anomaly Prospects Calibrated to an Industry-Wide Database
Authors Rocky Roden and Mike Forrest and Roger HoleywellOver the past decade, a consortium of oil companies in the US and Europe has developed a work process to interpret and risk seismic amplitude anomalies on exploration and development prospects. Over 175 prospects have been reviewed and documented in a database where the geology risk factors, seismic and rock physics data quality and amplitude anomaly characteristics have been analyzed to calculate the probability of geological success (Pg - flowable hydrocarbons). The drilling results for each prospect were compared to the calculated Final Pg, a function of the Initial Pg (geology) and the DHI Index which is the impact of the anomaly characteristics modified by data quality. The Final Pg and DHI Index compared to drilling result trends indicate a DHI Threshold Effect on prospects at the high end of the risk spectrum and a low Pg Threshold Effect at the low end of the spectrum. In other words, on the upper end of the spectrum there is a point at which a significant amount of the risks have been reduced to dramatically increase the Final Pg and DHI Index. On the lower end of the spectrum there is a threshold below which essentially all the wells are dry holes. Using these database trends, Pg can be calibrated to a wide range of 5% to 95% Final Pg. Therefore in DHI prospects, geoscientists should be more optimistic in analyzing the prospect risk if Final Pg and DHI Index are above certain threshold levels. Conversely, the low end of the risk profile prospects in the portfolio should probably be farmed out or not drilled with an overall goal of upgrading the exploration portfolio.
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Bayesian Risk Modification for Seismic Anomalies and Multiple Segment Prospect
More LessIt is well understood that anomaly information such as a flat spot, conformance, AVO, boosts the chance of success (COS) of an exploration target. Similarly, lack of anomaly information, when expected, attenuates the COS of the target. However, what happens when a prospect is composed of multiple targets (zones, compartments) with differential anomaly information? This paper presents a methodology that captures the intuitive notion that the aggregate effect of anomaly indicators at the target level depends on the degree of risk dependency between the discrete targets in the prospect. If the targets are relatively risk independent, then the prospect level COS will be a direct consequence of risk modification at the target level. On the other hand, if there is significant risk dependency, then the aggregate effect can be a relatively stronger boost or a significant attenuation depending on whether the signatures are consistent or mixed.
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Seismic Rock Physics, Sherlock Holmes and DHI Risking
By Rob SimmWe have been chasing ‘amplitude plays’ in earnest for over 20 years in this era of rock physics, AVO and seismic hi-fidelity. The published statistics and our own experience tell us that it pays off; exploration success rates are higher in plays where DHI technology is applicable. So, where to now?, more of the same presumably. We have all the checklists we need to ensure that procedures are followed together with systematic risking processes that help rank prospects around the globe. But oil and gas is found by the creative mind not committees, and filling in forms is no substitute for experience. The challenges faced by E & P companies requiring rigorous and consistent risking of amplitude supported prospects are not insignificant. Education, discipline integration and technology transfer from ‘experts’ to asset teams are significant issues, but the encouragement of a seismic rock physics mindset in seismic interpreters is the key to success.
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Amplitude Preservation for PSDM Processing
Authors Alfonso Gonzalez, Everett Mobley, Charles Wagner, Xiang Du, Robin Fletcher and Craig TophamAs seismic exploration moves to more complex and challenging geologic environments, Anisotropic Prestack Depth Migration is becoming the standard imaging technology. At the same time, there is high interest to use seismic amplitudes in these complex environments for risk assessment and reservoir characterization, objectives that require accurate amplitude preserving prestack depth migration. In this paper we review recent advances made to ensure depth migration algorithms maintain the quality of relative amplitudes. We verify with simple synthetics the amplitude response of Reverse Time Migration, Adaptive Beam Migration and Kirchhoff Migration algorithms, and demonstrate how these can be used successfully, under controlled circumstances, for AVO/AVA and Absolute Acoustic Inversion in media with lateral velocity variations.
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Fast Amplitude Analysis from Geo-Model Horizons
Authors Sebastien Lacaze and Fabien Pauget and Ingelise SchmidtIn this paper, we propose a new workflow, based on a global approach in seismic interpretation, to better analyze seismic amplitudes in a new horizon framework. This method seeks to overcome limitations in seismic such as wavelet polarity changes and amplitude drops and allows for building a continuous geological model for detailed understanding of the different reservoir levels of the survey. The amplitude extraction on numerous horizons in a short vertical window enables the delineation of geological prospects and therefore minimizes risks for drilling decisions. In this paper, we will describe the proposed workflow, its background technology and some case studies where amplitude extractions on horizons computed from the geo-model enabled to identify unseen events with classical approaches and facilitated fast modeling for forward modeling.
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Use of Quality and Anomaly Indicators in the QC of Seismic Inversion
More LessQuantifying the capability to repeat measurements of a signal or repeatability analysis is essential in geophysics and particularly for 4D seismic studies. Traditionally, it relies on statistical measurements like correlation coefficients and NRMS. We introduce two new repeatability indicators called “Quality” and “Anomaly” which allow the identification and quantification of inconsistencies inside a large amount of data. These indicators can also be used for AVO studies or after a seismic inversion to evaluate the match between the synthetic response of the inverted model and the observed seismic amplitudes. For prestack and 4D seismic inversion, the amount of data to analyze is significant. These indicators provide data reduction and quantify the ability of a given elastic model to reproduce seismic data. They are therefore useful to find the optimal parameterization of the inversion and to identify areas where further analysis and interpretation is needed. It is also used for qualifying different processing options for inversion purpose.
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Tricky DHIs for a Successful Exploration History in West Africa Deep Offshore
More LessDHIs have definitely become a crucial factor at steering the exploration activity in a mature block of the deep offshore of West Africa. Eni has drilled here many wells to test so far some thirty target levels. Many examples will be reviewed to show how the really tricky AVOs and DHIs have gained reliability and prediction power along the four year of exploration history in the block.
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Development and Utilization of an S-wave Type Land Streamer for High-Resolution Reflection Surveying
More LessHigh-resolution S-wave reflection surveying has been conducted on the paved surface utilizing Land Streamer which was originally developed by the author. The Land Streamer is featured by nonstretch towing member on which geophone units are mounted or hooked. The geophone units are coupled with paved surface without being planted to the ground. Since 1997, we have conducted production surveys using S-wave type Land Streamer at 27 sites, 46 lines, in Japan, and successfully delineated detailed near-surface structure down to 100 m. Especially, the tool has been utilized to active fault survey, because it is capable to discriminate vertical displacement of sediment layers less than 1 m owing to shorter wavelength of S-waves in the near-surface sediments compared with that of P-waves.
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Shear Wave Reflection Seismic by Combining Vibratory Sources and Land Streamer Receiver Setups
By Ulrich PolomSeismic imaging of the shallow subsurface to about 100 m in depth in high-resolution got a push on the demand in the last decade. The range of requests to image subsurface structures and also to assign shear wave velocities with respect to dynamic shear modulus analysis spread from very shallow targets in the first 10 m for e.g. building ground investigation for foundation to continuously increasing depths of more than 100 m for a wide range of shallow subsurface investigations. A special target in that frame was the subsurface investigation in urban environments, on paved surfaces and also below existing buildings, which can hardly be carried out by other geophysical methods. The performances of shear waves compared to P-waves allow new insights in this scale of subsurface investigations, if the method and the tools are adapted to these specific requirements. Beside only a few other research groups worldwide, LIAG research focussed to this demand since 2001 in developments of the shear wave reflection method, including research in tool development, acquisition operation, data processing, imaging, and interpretation. Over the years, a wide range of case studies led to continuously increasing experiences using this method. Since 2006 the achieved results and improvements also led to first breaks through to the commercial market.
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Is the Vila Franca de Xira Fault Still Active? A Shallow Seismic Reflection Shear-wave Study in an Intraplate Environment
The V. F. Xira fault (VFXF) is considered to be the most probable source of several destructive earthquakes that caused significant damage and loss of lives in Lisbon, Portugal and surrounding cities. The fault outcrops in Miocene sediments but is not seen to affect Quaternary terrains. The combination of low slip-rates in the area with erosion/sedimentation rates prevents the identification of active faults in the region. Our goal is to confirm if this fault has been active and to improve seismic hazard assessment in the LTV area. Previous P-wave seismic reflection data indicated the possibility of two shallow fault segments affecting the Holocene alluvium close to the VFXF outcrop. Due to the lack of resolution of this data to detect a small throw (< 2m) fault, the site was revisited with a high-resolution shallow S-wave reflection profile to confirm the fault segments but results were not completely conclusive. Here, we present reprocessed S-wave data and results of full-elastic seismic modelling to confirm the presence of the suspected faults. Clear indications of faulting were found: change of the shape and the amplitude of the reflection hyperbolae, discontinuities in the reflectors in the stacked section, shear-wave velocity dropping in anticipated the damage zones, and weak fault plane reflections. The results are analyzed further through seismic modeling. We conclude that the shallow fault segments affect the entire thickness of the Holocene alluvium and that the VFXF is active.
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Integrating High-resolution Shear Wave Seismics and Outcrop Data:A Case Study from Northern Germany
Authors Christian Brandes, Ulrich Polom and J. WinsemannShear wave seismic surveys allow a detailed assessment of the facies architecture and structural style of the Emme Delta in northern Germany. We combine outcrop and seismic data. The individual architectural elements that form the delta body were defined on the basis of their external geometry and the internal reflector pattern. Outcrops and borehole data were used to relate the seismic facies to the sedimentary facies. Special emphasize was placed on identifying faults, based on the reflector pattern. Faults are imaged as transparent lines that offset the reflectors. Syn-sedimentary faults can be indentified based on the wedge-shape of the growth strata. The faults have planar to slightly listric geometries and show vertical offsets in a range of 2 to 15 m. They form small graben and half-graben systems, which locally show roll-over structures. The fill of the half-grabens has a wedge-shaped geometry, with the greatest sediment thickness close to the fault.
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Seismic Reflection Surveys Using an SH-wave-type Vibrator Across Active Faults
Authors T. Kurahashi and Tomio InazakiThis paper describes the results of seismic reflection surveys conducted using a horizontally polarized shear (SH) wave-type vibrator. In the study, post-migrated CMP profiles of seismic reflection processing were produced to characterize subsurface structures across both the Asahiyama flexure and the Kozu-Matsuda fault. The throw of the top reflector enabled estimation of the cumulative vertical offset in the bedrock across the fault, and refraction tomography processing also revealed the SH wave velocity structure across it. The velocity structure in the subsurface around the fault decreased to 300 or 500 m/s. This was considered to be the result of unfavorable geological conditions with a low shear modulus. Against this background, SH-wave seismic reflection surveys are strongly expected to be very useful for acquiring images of bedrock across active faults, approximating the depth of bedrock, and identifying dataset signal anomalies that may indicate unfavorable geological conditions. These benefits are owed to the lower speed and shorter wavelength of SH waves.
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S-wave reflection profiling: Applicability and demonstrated use in Denmark at site and regional scale
Authors Kerim Martinez, Jos A. Mendoza and Andre PuginMulti-component reflection methods have gained acceptance for near surface mapping during recent years. Two case studies from Denmark employing shear wave reflection at different survey scales are presented. The first case study is a small site scale investigation to image the near surface lithology of a contaminated site. Here the S-wave reflection mapping was employed to update the Conceptual Site Model. The second application is a regional scale investigation with the aim to supplement mapping of unconsolidated sediments in buried valley structures as the mapping of these geological units is a primary objective in the hydrogeological mapping in Denmark. In both cases the method was utilised to obtain more detailed information on structures at the very near surface. Continuous advances in shear wave acquisition and processing methods contribute to increased applicability of shear wave reflection profiling in near surface characterisations.
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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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Frameworks for Modeling and Inversion
More LessInversion combines modelling with optimisation, two computational domains with quite different concepts and requirements. I suggest a few simple principles that help to organize software for these two types of tasks into linked frameworks. Code libraries based on these principles minimize the work involved in construction of modelling and inversion applications, and maximize the reliability of the end product. This paper presents example libraries constructed by the author’s research group, the principles on which they are based, and some examples of their use.
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Python for Geophysical Data Processing and Visualization
Authors Didrik Pinte, Eric Jones, Robert Kern and Pietro BerkesThe Python language excels as a tool for processing and visualizing scientific data. The array processing tools in NumPy handle multi-dimensional arrays and provide convenient representations for common geophysical data types such as well logs (1D), horizons (2D) and seismic volumes (3D). SciPy provides a wealth of efficient algorithms (interpolation, statistics, signal processing, etc.) common in processing such data, and matplotlib, chaco, and Mayavi provide plotting and 3D visualization capabilities. For those interested in harnessing the powers of the GPU, libraries such as CLyther, PyOpenCL, and PyCUDA offer a convenient bridge to these technologies. This presentation will provide an overview of these Python tools and demonstrate how to apply them to geophysical problems. We will provide examples of how these open source tools can be used for academic research as well as incorporated into commercial applications.
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Challenges Facing Open Source Software Developers and Users
More LessUsing open source E&P software for the first time or, in particular, becoming a developer has always meant that we have to put in an enormous effort in learning the ins and outs of the desired open source package. This requirement has, over the years, limited the number of potential users of open source software or has scared off new users. Addressing the reasons behind the big effort required to learn an open source E&P software will be the subject of this panel discussion.
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A Redeposited Chalk Reservoir (Upper Maastrichtian–Danian) in the Oseberg Field, Northern North Sea
More LessSetting and Stratigraphy The northern limit of the Upper Cretaceous chalks in the North Sea occurs at 60–61°N where carbonates interdigitate with mud-rich siliciclastics. This facies transition, coinciding with marked submarine palaeotopography descending from the Horda Platform to the Viking Graben, is recorded primarily by well-log data which demonstrate the temporal shifts in the position of the chalk:mudstone facies boundary. The Oseberg Field, 130 km west of Bergen (Norway), straddles this regional facies front; declining production from the primary Jurassic reservoirs in this field has focussed attention on hydrocarbon-bearing carbonates in the uppermost Shetland Group, mainly in the south of the field. Of particular interest is a 10–30 m thick chalk-rich section that caps the upper Campanian–Maastrichtian Hardråde Formation; a thin Danian carbonate unit (equivalent to the Ekofisk Formation farther south) is also recognisable locally, resting on a hiatal surface spanning the latest Maastrichtian (nannofossil subzone UC20d) and early Danian (subzones NNTp1–4E).
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Comparison of Fracturing Techniques for Unconventional Reservoirs
Authors Klaasvan Gijtenbeek and Markvan DomelenDue to their extremely low permeability, unconventional (UC) reservoirs such as tight sandstones, shale formations, and coal seams nearly all require hydraulic fracturing to maximize production. With marginal economics often at the forefront of the decision process to proceed with a field development project, successful fracture stimulation is critical for helping to de-risk these types of projects. Over the years the industry has used many different approaches in an effort to determine the “optimum” fracturing and completion design in different UC reservoirs. Using a variety of evaluation techniques that help to define success, one common theme emerges from the extensive amount of literature published: UC reservoirs respond most favourably to fracturing methods that are tailored to the specific reservoir conditions. This presentation will focus on some of the key factors that must be considered when designing hydraulic fracturing treatments for three different types of reservoirs; 1) low permeability sandstone formations, 2) shale reservoirs, and 3) coalbed methane (CBM) reservoirs, with a specific emphasis on comparing and contrasting the fracturing objectives between these different reservoir types.
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An Inversion Approach to Separating Sources in Marine Simultaneous Shooting Acquisition
Authors Roaldvan Borselen, Rolf Baardman, Bedanta Goswami and Eivind FromyrIn seismic exploration, there is continuous drive towards more dense data sampling to better image complex geological structures. Recent advances in acquisition such as Wide-Azimuth, Multi-Azimuth or Rich-Azimuth acquisition can deliver a more diverse range of source, azimuth and offset sampling. To collect such data, multiple source and receiver vessels are deployed, thereby increasing the costs of the survey significantly. In conventional acquisition, there is zero time overlap between shot records, and data are recorded discontinuously. The source domain is often poorly sampled, leading to aliasing. In simultaneous acquisition, data can be recorded continuously, and temporal overlap between shots is allowed. Consequently, more sources are fired during the same period of acquisition, which greatly enhances the flexibility in survey geometries. As a result, a more densely sampled data set in terms of source spacing, but also azimuth and offset distributions can be obtained. In terms of efficiency, simultaneous acquisition can contribute by reducing survey times, which is of particular value in critical situations where small acquisition timewindows dominate due to severe safety, environmental or economic restrictions. As such, from an acquisition point of view, simultaneous acquisition holds the promise of both efficiency and quality improvements. However, unless source separation can be achieved to a sufficiently high degree, the enormous potential benefits of simultaneous sources remain unrealized. Two approaches are currently utilized by the industry to achieve source separation: methods based on random noise attenuation and inversion-based methods. By regarding the energy from secondary sources as incoherent noise, after sorting the acquired data into an appropriate domain, the interference noise appears as random spikes which could be attenuated using well-known random noise removal procedures. Alternatively, inversion-driven methods aim to construct the separated sources through the minimization of a cost function that describes the “data misfit”. In such methods, incoherent energy is no longer regarded as noise that is to be removed. Instead, this energy is recognized as a representation of coherent events belonging to (one of) the interfering shots. An inversion approach aims to distribute all energy in the blended shot records by reconstructing the individual unblended shot records at their respective locations. In this abstract, an inversion-driven method is utilized that uses coherency measures to reconstruct the individual shot gathers from the blended data. The method is demonstrated to be capable of separating sources, even in the presence of strong diffraction energy. The method can be used in conjunction with other methods, resulting in so-called hybrid solutions. A simultaneous source wide-azimuth 3D data set from the Gulf of Mexico is presented.
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A Land Example of Full Waveform Inversion and Distance Separated Simultaneous Sweeping
Authors R.É. Plessix, G. Baeten, J. W.de Maag, F.ten Kroode and R. J. ZhangSimultaneous or blended shooting has been developed to reduce the acquisition cost while keeping a dense coverage. The processing and imaging are complicated by the cross-talks between the simultaneous sweeps. A compromise can be achieved with distance separated simultaneous sweeping when we are primarily interested in reflected events since by design, the interferences at the target are avoided and the shots can be easily separated. At large offsets which are relevant when full waveform inversion is used to construct the background velocity, cross-talks occur. Based on the single shot, single receiver land data set recorded in Inner Mongolia, China, we simulated a 2D distance separated simultaneous sweeping acquisition. We then carried out several full waveform inversions to evaluate the effects of the cross-talks. By adapting the offset weighting traditionally applied, a multi-scale full waveform inversion of the blended data produces a background velocity model that is very similar to the model obtained with the original unblended data.
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On the Relation between Seismic Interferometry and the Simultaneous-source Method
Authors Kees Wapenaar, Joostvan der Neut and Jan ThorbeckeIn seismic interferometry the response to a virtual source is created from responses to sequential transient or simultaneous noise sources. In the simultaneous-source method, overlapping responses to sources with small time delays are recorded. Seismic interferometry and the simultaneous-source method are related. In this paper we make this relation explicit by discussing deblending as a form of seismic interferometry by multidimensional deconvolution.
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Blended Acquisition with Optimized Dispersed Source Arrays
Authors Guus Berkhout and Gerrit BlacquièreUntil now, blended source arrays are configured with equal source units: ‘homogeneous blending’. We propose to extend the blending concept to inhomogeneous blending, meaning that a blended source array consists of different, narrowband source units with different central frequencies.
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Waveform Inversion Overview: Where Are We? And What Are the Challenges?
More LessSince at least forty years, mathematicians and geophysics have studied seismic waveform inversion. Its computational cost and its ill-posedness (i.e. the presence of local minima and the non-uniqueness of the solutions) make its use difficult with real-sized problems. Nevertheless, with the improvements in data quality and in acquisition and the increase in computer power, several real data examples have been reported. In the literature, waveform inversion has been formulated either in the data domain or in the model domain. In this presentation, I shall discuss the data-domain formulation, where we minimize the misfit between the observed data and the computed data that are direct solutions of the wave equation. I shall consider three main applications. In the first group of applications, waveform inversion is solved with a global optimization and a simple 1D forward modeling. The objective is, generally, to derive some petrophysical parameters from the seismic reflection traces. In the second group of applications, waveform inversion is solved with a local optimization assuming a known background velocity, the objective is to retrieve reflectivity or impedance maps from reflection data. In the third group of applications, waveform inversion is solved with a local optimization and a multiscale approach. The goal is to estimate the background velocity mainly from low-frequency and long-offset data. While reviewing these waveform inversion applications, I shall discuss the challenges we are still facing. The focus of the presentation will be the applications of waveform inversion for macroscopic (background velocity) model building.
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