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69th EAGE Conference and Exhibition - Workshop Package
- Conference date: 11 Jun 2007 - 14 Jun 2007
- Location: London, UK
- ISBN: 978-94-6282-105-7
- Published: 10 June 2007
1 - 50 of 76 results
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Recent developments in curvelet-based seismic processing
More LessRecent developments in curvelet-based seismic processing Felix J. Herrmann (Seismic Laboratory for Imaging and Modeling Department of Earth and Ocean Sciences The University of British Columbia) SUMMARY____________________________________________________________ In this paper we present recent developments in nonlinear curvelet-based sparsity-promoting formulations of problems in the seismic data processing flow. We present our latest work on a parallel curvelet transform and recent work on a curvelet-regularized formulation for the focal transform the prediction of multiples and the computation of the inverse data space. We show that the curvelet’s wavefront detection capability and invariance under wave propagation lead to a formulation of these problems
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The seislet transform and seislet frames
By S. FomelWorkshop 8 The seislet transform and seislet frames Sergey Fomel (University of Texas at Austin) SUMMARY____________________________________________________________ I introduce the seislet transform: a digital wavelet-like transform tailored specifically for representing seismic data. The transform provides a multiscale orthogonal basis with basis functions aligned along seismic event slopes in the input data. In the case of multiple conflicting slopes the basis decomposition can be replaced with a frame composed of different bases. I define seislets with the help of the wavelet lifting scheme combined with local plane-wave destruction. The main objective is an optimal seismic data compression for designing efficient algorithms. Many
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Local wavefield operators, radon transforms and sparsity
Authors M. D. Sacchi, S. T. Kaplan and U. TheuneLocal Wavefield Operators Radon Transforms and Sparsity Mauricio D. Sacchi (Department of Physics University of Alberta) Sam T. Kaplan (Department of Physics University of Alberta) and Ulrich Theune (Statoil Research Center Trondheim) SUMMARY____________________________________________________________ The Radon transform is a powerful method that has been used to filter coherent noise from seismic records and to reconstruct seismic data. In addition it has a long history in image processing as a tool for feature extraction. An important shortcoming in exploration seismology however is the requirement of simple integration paths that often do not match the spatiotemporal structure of seismic waveforms. The latter can
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Seismic data analysis with dual-tree M-band wavelet transforms
More LessSeismic Data Analysis With Dual-Tree M-Band Wavelet Transforms Laurent Duval (Institut Français du Pétrole (IFP)) Caroline Chaux (ARIANA research group) and Stéphan Ker (IFREMER Marine Geosciences Department) SUMMARY____________________________________________________________ The complexity of seismic data still challenges signal processing algorithms in several applications. The rediscovery of wavelet transforms by J.Morlet et al. has allowed improvements in addressing several data representation (local analysis compression) and restoration problems. However despites their achievements traditional approaches based on discrete and separable (both for computational purposes) wavelets fail at efficiently representing directional or higher dimensional data features such as line or plane singularities especially in severe noise
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Wavelet based self-similarity analysis in seismic data processing
Authors Z. Yu and D. WhitcombeWavelet based self-similarity analysis in seismic data processing Zhou Yu (BP) and David Whitcombe (BP) SUMMARY____________________________________________________________ This paper shows using synthetic examples how by using the wavelet transform we can exploit the principle of self-similarity to overcome a number of limitations within seismic data. Firstly we demonstrate that the plane wave solution to the wave equation has self-similarity when dispersion is too small to be considered. When seismic data is decomposed using the orthogonal wavelet basis this self-similarity is further enhanced by the fact that the orthogonal wavelet bases at different scales overlap in frequency. Decimation in the pyramid decomposition
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Curvelet reconstruction with sparsity-promoting inversion:successes and challenges
Authors G. Hennenfent and F. J. HerrmannCurvelet reconstruction with sparsity-promoting inversion:successes and challenges Gilles Hennenfent (Seismic Laboratory for Imaging and Modeling Department of Earth and Ocean Sciences The University of British Columbia) and Felix J. Herrmann (Seismic Laboratory for Imaging and Modeling Department of Earth and Ocean Sciences The University of British Columbia) SUMMARY____________________________________________________________ In this overview of the recent Curvelet Reconstruction with Sparsity-promoting Inversion (CRSI) method we present our latest 2-D and 3-D interpolation results on both synthetic and real datasets. We compare these results to interpolated data using other existing methods. Finally we discuss the challenges related to sparsity-promoting solvers for the large-scale problems
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Elimination of migration artifacts using the multiscale radon transform
Authors A. Droujinine, G. Baeten, F. Kuiper and R. WervelmanElimination Of Migration Artifacts Using The Multiscale Radon Transform Alexander Droujinine (Shell International Exploration & Production B. V.) Guido Baeten (Shell International Exploration & Production B. V.) Frans Kuiper (Shell International Exploration & Production B. V.) and Rob Wervelman (Nederlandse Aardolie Maatschappij (NAM)) SUMMARY____________________________________________________________ The suppression of high-amplitude migration artifacts (refractions prismatic waves etc.) from common image gathers (CIGs) represents an important part of the Kirchhoff PP PSDM workflow in complex terrains. Based on the characteristics of noise in the CIG domain using conventional Radon or FK filters has proved to be unsuccessful due to the offset limitation and illumination
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Just diagonalize: a curvelet-based approach to seismic amplitude recovery
Authors F. J. Herrmann and P. MoghaddamJust diagonalize: a curvelet-based approach to seismic amplitude recovery Felix J. Herrmann (Seismic Laboratory for Imaging and Modeling Department of Earth and Ocean Sciences The University of British Columbia) and Peyman Moghaddam (Seismic Laboratory for Imaging and Modeling Department of Earth and Ocean Sciences The University of British Columbia) SUMMARY____________________________________________________________ In this presentation we present a nonlinear curvelet-based sparsity-promoting formulation for the recovery of seismic amplitudes. We show that the curvelet’s wavefront detection capability and invariance under wave propagation lead to a formulation of this recovery problem that is stable under noise and missing data. EAGE 69 th Conference &
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Leading-order seismic imaging using curvelets
Authors H. Douma and M. V. de HoopLeading-Order Seismic Imaging Using Curvelets H. Douma (Department of Geosciences Princeton University) and M.V. de Hoop (Center for Computational and Applied Mathematics and Department of Earth and Atmospheric Sciences Purdue University) SUMMARY____________________________________________________________ We show that with curvelets the leading-order approximation (in angular frequency horizontal wavenumber and migrated location) to Kirchhoff depth-migration becomes a simple transformation of the coordinates of the curvelets in the data combined with amplitude scaling. This transformation is calculated using map migration which uses the local slopes provided by the curvelet decomposition of the data. We verify the accuracy of the method using numerical examples for homogeneous
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Seismic migration using the complex shiftable pyramid
Authors T. Nguyen and H. ChaurisSeismic migration using the complex shiftable Pyramid Truong Nguyen (Ecole des Mines de Paris) and Hervé Chauris (Ecole des Mines de Paris) SUMMARY____________________________________________________________ We consider how the 2-D seismic Kirchhoff migration scheme can benefit from a recently introduced shiftable directional pyramid. First the pyramidal dual-tree directional filter bank is presented with some modifications to make it more suitable to the seismic migration problem. Since the decomposition by this filter bank is multiresolution and multidirectional it can be regarded as a digital curvelet transform. We implement the first-order approximation of the Kirchhoff migration scheme. It essentially consists of a rotation a
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Towards interactive seismic imaging with curvelets
Authors H. Chauris and T. NguyenTowards interactive seismic imaging with curvelets Hervé Chauris (Ecole des Mines de Paris) and Truong Nguyen (Ecole des Mines de Paris) SUMMARY____________________________________________________________ We present a new methodology towards interactive seismic imaging. A first seismic image is obtained with a prestack depth migration code run in a reference velocity model. The objective is to efficiently derive what the migrated section would be in a perturbed velocity model. Instead of migrating the full input data in the second velocity model the reference migrated section is first decomposed in the curvelet domain. This provides coefficients associated to the representation of local plane waves
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Interactive seismic imaging by fast beam migration
Authors F. Gao, P. Zhang, B. Wang, G. Thomas-Collignon and V. DirksInteractive seismic imaging by fast beam migration Fuchun Gao (CGGVeritas) Po Zhang (CGGVeritas) Bin Wang (CGGVeritas) Guillaume Thomas-Collignon (CGGVeritas) and Volker Dirks (CGGVeritas) SUMMARY____________________________________________________________ This paper presents a Fast Beam migration algorithm which has been specifically designed to facilitate very rapid migration turnarounds to allow for interactive velocity model building and validation. The very fast imaging turnaround is achieved by only migrating pre-picked events in a wavelet by wavelet fashion. Coherent noise and migration artifacts are reduced compared to classical Kirchhoff migration techniques by using a sophisticated event selection scheme during the event picking phase and by subsequent multi-path migration
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Seismic migration in the coupled ray-parameter domain
Authors M. K. Sen, P. L. Stoffa and R. K. SeifoullaevSeismic migration in the coupled ray-parameter domain Mrinal K. Sen (John A. and Katherine G. Jackson School of Geosciences The University of Texas at Austin) Paul L. Stoffa (John A. and Katherine G. Jackson School of Geosciences The University of Texas at Austin) and Roustam K. Seifoullaev (John A. and Katherine G. Jackson School of Geosciences The University of Texas at Austin) SUMMARY____________________________________________________________ Seismic data transformed to the plane wave domain offer several advantages in seismic processing and parameter estimation. .Simple slant stacking can be used to identify the plane waves recorded along the measurement surface. Alternatives to linear slope
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Beamlet and directional wavelet: phase-space localization and wave propagation
By R-S. WuBeamlet and Directional Wavelet: Phase-Space Localization and Wave Propagation Ru-Shan Wu (University of California) SUMMARY____________________________________________________________ First I review the development of beamlet decomposition and propagation in the framework of phase-space localization especially the space-wavenumber localization. Then the relation between the beamlet and the directional wavelet is discussed in the context of wave propagation. Beamlet and directional wavelet have the same capacity of representing phasespace localized wavefield due to the angle-wavenumber correspondence. Some examples of propagator decomposition and seismic imaging using local cosine beamlet propagator are given. EAGE 69 th Conference & Exhibition — London UK 11 - 14 June 2007
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On uncertainties propagation in modeling and interpretation of EM data concerning saturated granular media
By L. SambuelliOn uncertainties propagation in modeling and interpretation of EM data concerning saturated granular media. Luigi Sambuelli (DITAG – Politecnico di Torino) SUMMARY____________________________________________________________ In this study I calculate the uncertainties occurring either when from experimental E and EM data one wants to estimate the porosity of a two-phase saturated media; or when from the given properties of a saturated granular media one wants to estimate the E and/or EM parameters (conductivity or permittivity). I analyze some of the most common mixing laws used in geophysics. I pay particular attention to uncertainties achievable in field survey to make the user aware of
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Trends in waterborne electrical and EM induction methods for high resolution sub-bottom imaging
By K. E. ButlerTrends in waterborne electrical and EM induction methods for high resolution sub-bottom imaging Karl E. Butler (University of New Brunswick) SUMMARY____________________________________________________________ Electrical and electromagnetic (EM) methods are used extensively for near-surface applications on land but their use on water remains relatively novel. Shallow water applications are becoming more common however as there has been growing recognition over the past five years of the useful information these methods can provide in groundwater hydrology sedimentology engineering and other fields. In many applications spatial variations in resistivity variations are useful as a proxy for variations in another bulk material property such as pore
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Advanced processing and acquisition methods to image within and beneath shallow water bodies with ground-penetrating radar
Authors J. H. Bradford and T. BrostenAdvanced processing and acquisition methods to image within and beneath shallow water bodies with ground-penetrating radar John H. Bradford (CGISS Boise State University) and Troy Brosten (CGISS Boise State University) SUMMARY____________________________________________________________ We have investigated acquisition and processing methods to maximize the information content of GPR surveys in a variety of shallow water investigations. In a study of permafrost melt beneath Arctic streams we conducted 3D surveys in remote locations that required spatial (horizontal and vertical) precision on the order of 2 cm. Integrating kinematic geodetic grade GPS measurements with GPR data acquisition provided the necessary spatial control. 3D migration produced
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EC imaging of aquifers beneath watercourses of the Murray Darling Basin, Australia
More LessEC Imaging of aquifers beneath watercourses of the Murray Darling Basin Australia David Allen (Groundwater Imaging Pty. Ltd.) and Torleif Dahlin (Teknisk Geologi Lunds Tekniska Högskola Lunds Universitet) SUMMARY____________________________________________________________ Electrical conductivity imaging of numerous rivers segments and canals of the Murray Darling Basin Australia has been conducted using both geo-electric arrays and transient electromagnetic devices towed along the watercourses. Permeable pathways beneath the watercourses are clearly evident due to fresh water moving downwards or saline water moving upwards through them. EC imaging is proving to be a very cost effective tool for managing saline inflow to rivers and seepage loss
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Marine geoelectrical prospecting for soft structures characterization in shallow water: field and laboratory test
Authors G. Losito, P. L. Aminti, L. Martelletti, J. Grandjean, A. Mazzetti, A. Trova and G. BenvenutiMarine geoelectrical prospecting for soft structures characterization in shallow water: field and laboratory test. G.Losito (Dipartimento di Ingegneria Civile – Università di Firenze) P.L. Aminti (Dipartimento di Ingegneria Civile – Università di Firenze) L. Martelletti (Dipartimento di Ingegneria Civile – Università di Firenze) J.-M.Grandjean (Freelance engineer) A. Mazzetti (ENKI s.r.l.) A. Trova (Dipartimento di Ingegneria Civile – Università di Firenze) and G. Benvenuti (Dipartimento di Ingegneria Civile – Università di Firenze) SUMMARY____________________________________________________________ In June 2006 on the Tuscany shore we started field tests in order to evaluate the capabilities to characterize and map a buried groin in a shallow water
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Using controlled source EM methods to constrain physical properties of the uppermost seafloor: An example of instrumentation and a case study from a gas Pock-Mark offshore Ireland
Authors X. Garcia, R. L. Evans and X. MonteysUsing Controlled Source EM Methods to Constrain Physical Properties of the Uppermost Seafloor: An Example of Instrumentation and a Case Study from a Gas Pock-Mark Offshore Ireland. Xavier Garcia (Dublin Institute for Advanced Studies (DIAS)) Rob. L. Evans (Dept of Geology and Geophysics Woods Hole Oceanographic Institution) and Xavier Monteys (Geological Survey of Ireland) SUMMARY____________________________________________________________ We discuss a towed frequency-domain magnetic-dipole electromagnetic (EM) system that is used to map the uppermost 20 m of seafloor in a variety of settings. To date the system has been used in water depths of ranging from 10-20m nearshore out to 1300 m on
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Water bottom electrical tomography in the river Tiber
Authors L. Orlando and L. TramontiWATER BOTTOM ELECTRICAL TOMOGRAPHY IN THE RIVER TIBER Luciana Orlando (Dept. Idraulica Trasporti e Strade “La Sapienza University”) and Luigi Tramonti (Freelance researcher) SUMMARY____________________________________________________________ The paper deals with electrical tomography performed on the Tiber river bottom with the goal of reconstructing the setting of sediments and characterising their lithologies. The data were acquired by a cable lying along the river bottom equipped with 24 electrodes set 1m apart and with Wenner dipole-dipole and Schlumberger spreads. The efficiency of electrical tomography was validated with 1D theoretical modelling performed with finite differences algorithm. We have obtained to constrain the uncertainties in the
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Integration of high-resolution seismics and multi-offset GPR for shallow freshwater basins studies: a case history from the Cheko Lake area (Russia)
Authors M. Pipan, G. Dal Moro, E. Forte and L. GasperiniIntegration of high-resolution seismics and multioffset GPR for shallow freshwater basins studies: a case history from the Cheko Lake area (Russia) M.Pipan (University of Trieste) G. Dal Moro (University of Trieste) E.Forte (University of Trieste) L.Gasperini (ISMAR-Bologna) SUMMARY____________________________________________________________ This study focuses on the integration of linear multi-fold GPR techniques and High- Resolution Seismics to study the Cheko Lake area (101 o E 62 o N). Primary objectives of the study are acoustic and electromagnetic subsurface imaging in the offshore area and in the southern coastal sector and characterization of subsurface properties of the materials. Imaging and material characterization aim at
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Stream-Axis EM from a helicopter: identifying salinity sources in a large river basin
Authors J. G. Paine, E. W. Collins and H. S. NanceStream-Axis EM from a Helicopter: Identifying Salinity Sources in a Large River Basin Jeffrey G. Paine (Bureau of Economic Geology Jackson School of Geosciences The University of Texas at Austin) Edward W. Collins (Bureau of Economic Geology Jackson School of Geosciences The University of Texas at Austin) and H.S. Nance (Bureau of Economic Geology Jackson School of Geosciences The University of Texas at Austin) SUMMARY____________________________________________________________ We combined multifrequency airborne EM measurements of apparent ground conductivity with chemical analyses of surface water to delineate natural and oil-field salinity sources that degrade water quality in the upper Colorado River (western Texas U.S.A).
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GeoChirp 3D: high resolution 3D sub-bottom profiling
Authors M. Gutowski, J. M. Bull, J. K. Dix, T. J. Henstock, P. I. Hogarth and T. M. HillerGeoChirp 3D: High Resolution 3D Sub-Bottom Profiling Martin Gutowski (GeoAcoustics Ltd) Jon M. Bull (National Oceanography Centre) Justin K. Dix (National Oceanography Centre) Timothy J. Henstock (National Oceanography Centre) Peter I. Hogarth (GeoAcoustics Ltd) and Thomas M. Hiller (GeoAcoustics Ltd) SUMMARY____________________________________________________________ This article describes the concept of high resolution 3D sub-bottom profiling outlines the design and application of the GeoChirp 3D system and demonstrates its capabilities using a dataset imaging a buried cofferdam in the Port of Southampton (UK). EAGE 69 th Conference & Exhibition — London UK 11 - 14 June 2007 Introduction The hydrocarbon exploration industry has routinely
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High-resolution 2D deep-towed seismic system for shallow water surveying
Authors M. Tokarev, N. Kuzub and R. PevznerHigh-resolution 2D deep-towed seismic system for shallow water surveying Mikhail Tokarev (Lomonosov Moscow State University) Nikolay Kuzub (Lomonosov Moscow State University) and Roman Pevzner (Lomonosov Moscow State University) SUMMARY____________________________________________________________ Under certain conditions when it is needed to ensure high resolution (tens of cm) with relatively low penetration (10-15 m) at relatively deep water (tens of m) deep towed seismic systems have significant advantages comparing to the conventional seismic systems. These conditions are typical for inspection of sites for drilling platform construction as well as for lithological biological and environmental investigations etc. Deep-towed systems demonstrate robustness to rough weather conditions lower
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AVO analysis for the study of lacustrine sediments, in Lake Geneva, Switzerland
Authors D. Hammami and F. MarillierAVO analysis for the study of lacustrine sediments in Lake Geneva Switzerland D. Hammami and F. Marillier SUMMARY____________________________________________________________ A new system was developed to acquire 2D and 3D high-resolution seismic data in lakes. More than 400 km of 2D data and three 3D data volumes made it possible to study different features in Lake Geneva. To better understand the physical characteristics of sedimentary deposits in this lake we carried out a quantitative seismic analysis of our data. Accurate amplitude measurements were obtained after correction for the frequency response of the hydrophones that were individually calibrated. After amplitude preserving processing followed
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Shallow time slices from deep 3-D time slices: a new world discovered?
Authors B. F. Paap, J. H. Brouwer and S. van HeterenShallow time slices from deep 3-D time slices: a new world discovered? Bob F. Paap (TNO Built Environment and Geosciences – Geological Survey of the Netherlands) Jan H. Brouwer (TNO Built Environment and Geosciences – Geological Survey of the Netherlands) and Sytze van Heteren (TNO Built Environment and Geosciences – Geological Survey of the Netherlands) SUMMARY____________________________________________________________ In recent years shallow time slices of marine 3D-seismics acquired for petroleum-exploration purposes have been used to reconstruct paleolandscapes that are presently buried and submerged. These shallow time slices provide information on the distribution of various lithological units that are present in the upper
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UHR marine 3D seismic investigation of the Limantepe/Carantina Island archaeological sites (Urla/Turkey)
More LessUHR Marine 3D Seismic Investigation of the Limantepe/Carantina Island Archaeological Sites (Urla/Turkey) Christof Müller (Christian-Albrechts-University Kiel Germany) Susanne Woelz (Christian-Albrechts-University Kiel Germany) Tobias Jokisch (Christian-Albrechts-University Kiel Germany) Yasar Ersoy (Bilkent University Ankara Turkey) Gert Wendt (Rostock University Rostock Germany) and Wolfgang Rabbel (Christian-Albrechts-University Kiel Germany) SUMMARY____________________________________________________________ As part of the SEAMAP-3D project 2D and 3D high resolution seismic investigations of the Iskele (Limantepe and Necropolis) and Carantina Island shore areas were carried out in October 2006. Archaeological findings indicate that sea level change led to the submersion of man-made structures. Based on a 2D reconnaissance survey two areas were selected
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High-resolution seismic from LakeTana, Ethiopia
Authors C. R. Bates and D. HuwsHigh-resolution Seismic from LakeTana Ethiopia C. Richard Bates (University of St Andrews) and D. Huws (University of Wales) SUMMARY____________________________________________________________ Two high-resolution seismic surveys have recently been conducted at Lake Tana as part of a regional palaeo-climate study. Lake Tana the source of the Blue Nile is located in the Ethiopian Highlands and as the largest northern latitude sub-tropical lake in Africa it contains an important record of regional climate events. The lake is approximately 70km by 50km but has an average depth of only 8m. Seismic data acquired using both a Geoacoustics Chirp system and a Seistec Boomer showed an
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Seismic data acquisition in shallow water: A case history In The Venice Lagoon
Authors L. Baradello and F. DondaSeismic Data Acquisition In Shallow Water: A Case History in The Venice Lagoon Luca Baradello (Istituto Nazionale di Geofisica Sperimentale – OGS) and Federica Donda (Istituto Nazionale di Geofisica Sperimentale – OGS) SUMMARY____________________________________________________________ This work shows how is possible to collect High Resolution Seismic data in very shallow water with a boomer and a mono-channel streamer. Using mono-channel is necessary for improving Signal/Noise but in shallow water the aliasing ruins the signal. We tested a special acquisition geometry in which the streamer and the plate are towed on opposite sides (only lateral offset) behind the stern. In this case the
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Irregular sampling from aliasing to noise
More LessIrregular sampling from aliasing to noise G. Hennenfest (University of British Columbia) SUMMARY____________________________________________________________ EAGE 69 th Conference & Exhibition — London UK 11 - 14 June 2007 Adequate sampling of seismic data is traditionally understood as evenly-distributed time and space measurements of the reflected wavefield. Moreover the sampling rate along each axis must be equal to or above twice the highest frequency/wavenumber of the continuous signal being discretized (Shannon/Nyquist sampling theorem). In practice however seismic data is often irregularly and/or sparsely sampled along spatial coordinates which is generally considered as a nuisance since it breaks one or both previouslystated conditions
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Near Surface Noise Characterization With Multicomponent Measurements
Authors E. Kragh and E. MuyzertNear Surface Noise Characterization With Multicomponent Measurements Ed Kragh (Schlumberger Cambridge Research (SCR)) and Everhard Muyzert (Schlumberger Cambridge Research (SCR)) SUMMARY____________________________________________________________ On land the effect of the near-surface is the major cause of poor seismic data quality. Surface noise heterogeneity causing scattering statics coupling variations wavefield attenuation and anisotropy all degrade the quality of the wavefield recorded at the surface. To further improve the quality of land seismic data one approach is to gain a fundamental understanding of the wave propagation in the near-surface. As an example a consistent observation which requires explaining is the amount of cross-line energy recorded
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Noise Reduction in Land Seismic Acquisition by the use of High-fold, Multi-Component Single Point Sensors
By B. DonnellyNoise Reduction in Land Seismic Acquisition by the use of High-fold Multi-Component Single Point Sensors. Brian Donnelly (Input/Output UK Ltd) SUMMARY____________________________________________________________ We discuss how recent developments in seismic recording techniques can be used to dramatically improve noise attenuation in land seismic acquisition. The use of wireless technology allows for unrestricted fully-configurable survey geometries making super-high fold recording practical. The optimised orthogonal survey spread lends itself to the use of Offset Vector Tiling methods for geometry regularisation and enhanced seismic data processing. Married to the use of multi-component sensors this yields a full-wavefield image with data quality which has not been
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Attenuating the ice flexural wave on arctic seismic data
By D. C. HenleyAttenuating the ice flexural wave on arctic seismic data David C. Henley (CREWES) SUMMARY____________________________________________________________ Although providing good surface coupling for seismic surveying in the arctic floating ice also generates of one of the most powerful known coherent noises—the ice flexural wave. This set of modes is unique in its massive dispersion with the highest frequency energy propagating at near the ice compressional velocity and the lowest frequencies often moving at speeds well below air velocity. While its large dispersion makes the ice flexural wave difficult to attenuate using conventional techniques such as f-k filtering it suggests the use of the
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Improvements to Radon-based noise removal
By M. D. SacchiImprovements to Radon-based noise removal Mauricio D. Sacchi (Department of Physics University of Alberta) SUMMARY____________________________________________________________ I will discuss different strategies to improve the performance of Radon-based filtering with application to coherent noise removal. In particular I propose to combine multi-parameter Radon transforms (operators with more than one type of integration path) with filter banks. The latter significantly increases our ability to separate signal from coherent noise. I also examine new ways to gaining efficiency in the computation of time-variant Radon transforms. In particular time-variant multi-parameter Radon transforms can be quite demanding from the computational point of view when used for
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Examples of 3D Noise Attenuation Processes Applied to Land and OBC data
More LessExamples of 3D Noise Attenuation Processes Applied to Land and OBC data Simon Shaw (ConocoPhillips) Chuck Mosher (ConocoPhillips) Stephen Chiu (ConocoPhillips) Yunqin Shen (ConocoPhillips) Jack Howell (ConocoPhillips) and Mark Wuenscher (ConocoPhillips) SUMMARY____________________________________________________________ Land and ocean bottom seismic data can be readily acquired with wide azimuth acquisition geometries. The orthogonal cross spread has advantages for noise attenuation including that ground roll can be well sampled and these 3D gathers allow for the application of more powerful 3D processing algorithms. In this workshop we will present a variety of synthetic and field data results that compare and contrast some of these 3D
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A review of some powerful noise elimination techniques for Land Processing
Authors J. A. Stein and T. Langston“A review of some powerful noise elimination techniques for Land Processing” Jaime A. Stein (Geotrace Technologies Inc.) and Tom Langston (Geotrace Technologies Inc.) SUMMARY____________________________________________________________ As part of a successful processing project especially on land a proper suite of noise elimination techniques is paramount. The failure to eliminate or at least to reduce the effect of any of these noises can dramatically affect the outcome of the interpretation. Noises left in the data are virtually impossible to eliminate in the latter stages of processing and have devastating consequences for interpretation. We herby review three of the most used and successful technaiques
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Local Directional And Uncoherent Seismic Noise Filtering With Oversampled Filter Banks
Authors J. Gauthier, M-C. Cacas and L. DuvalLocal Directional And Uncoherent Seismic Noise Filtering With Oversampled Filter Banks Jérôme Gauthier (Institut Français du Pétrole (IFP)) Marie-Christine Cacas (Institut Français du Pétrole (IFP)) and Laurent Duval (Institut Français du Pétrole (IFP)) SUMMARY____________________________________________________________ Seismic data are subject to different kinds of unwanted perturbations. These random or organised noises which can be acquisition or processing related for instance may disturb geophysical interpretations and thwart attempts at automated processing methods. Since the relative features (e.g. amplitude spectrum) of the signals of interest and the noises may vary locally signal and noise separation is obtained by a local data-driven filtering with two
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Effective data denoising using new data driven and model driven algorithms
Authors M. Buia, E. Loinger and P. MarchettiEffective data denoising using new data driven and model driven algorithms Michele Buia (Eni) Eugenio Loinger (Eni) and Paolo Marchetti (Eni) SUMMARY____________________________________________________________ The noise problem in land seismic is sometimes a real show stopper for a correct geological interpretation; in particular there are environments like thrust belts where it is impossible to get “at least an image” of the subsurface despite a careful processing work. Unfortunately new frontier of exploration sometimes have to deal with such bad areas and with not properly acquired seismic data. In this paper will be described two processing algorithms that demonstrated themselves practically effective in
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Using Least-Squares to Reduce Migration Noise
Authors R. Leggott, R. Wombell, T. Noss, G. Conroy and G. WilliamsUsing Least-Squares to Reduce Migration Noise Richard Leggott (CGGVeritas) Richard Wombell (CGGVeritas) Tony Noss (CGGVeritas) Graham Conroy (CGG Veritas) and Gareth Williams (CGGVeritas) SUMMARY____________________________________________________________ Seismic data should be migrated before analysis and interpretation. However the process of migration is often a source of noise; this is especially true of onshore seismic data where an “acquisition footprint” is a common problem. The origin of this migration noise lies in the difficulty of computing an accurate migration operator. If simplifying assumptions are used such as regular acquisition geometry then the computation of the migration operator becomes practical. Such assumptions are almost universal
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Near surface models derived from ground roll, guided waves and Scholte waves
By E. MuyzertNear surface models derived from ground roll guided waves and Scholte waves Everhard Muyzert (Schlumberger Cambridge Research) SUMMARY____________________________________________________________ In normal exploration practice we make strenuous efforts to remove the effect of ground roll and other sources of self noise from the recorded data. We do this in the field with arrays and in the computer with sometimes complex processing schemes. Most of this so called self noise is a representation of the source wave field's response to the Earth and hence it should be usable as signal to provide extra information about the Earth and in particular about the near
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Diffraction imaging for fracture detection
Authors S. Fomel, E. Landa and M. T. TanerDiffraction imaging for fracture detection Sergey Fomel (University of Texas at Austin) Evgeny Landa (OPERA) and M. Turhan Taner (Rock Solid Images) SUMMARY____________________________________________________________ EAGE 69 th Conference & Exhibition — London UK 11 - 14 June 2007 INTRODUCTION Naturally fractured reservoirs are an important target for the oil industry. Such reservoir development requests information about the fractures obtained from seismic data. Usually this information comes from the effective media theories that predict a general elastic behaviour of a solid containing many inhomogeneities whose sizes are small (Grechka and Kasprov 2006). It is assumed that because of a small size (much
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Curvelet applications in surface wave removal
Authors C. Yarham, G. Hennenfent and F. J. HerrmannCurvelet Applications in Surface Wave Removal Carson Yarham (Seismic Laboratory for Imaging and Modeling Department of Earth and Ocean Sciences The University of British Columbia) Gilles Hennenfent (Seismic Laboratory for Imaging and Modeling Department of Earth and Ocean Sciences The University of British Columbia) and Felix J. Herrmann (Seismic Laboratory for Imaging and Modeling Department of Earth and Ocean Sciences The University of British Columbia) SUMMARY____________________________________________________________ Ground roll removal of seismic signals can be a challenging prospect. Dealing with undersampleing causing aliased waves amplitudes orders of magnitude higher than reflector signals and low frequency loss of information due to band
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Efficient optical architectures for seismic reservoir monitoring
Authors A. V. Strudley and P. NashFibre-optic seismic sensor systems are gaining increased interest in the context of field-wide permanent seismic reservoir monitoring. This interest stems from the expectation of improved reliability and lower through life cost compared to electronic component systems. Meeting these expectations for high channel count (>10 000 channels) is critically dependent on the optical architecture employed since this dictates requirements on total fibre and optical component count. A particularly attractive optical architecture using Time and Dense Wavelength Division Multiplexing is described. Examples of the implementation of this architecture in a field test of a 4C seismic optical sensor array are presented. A system noise floor below -140dB g/rt Hz, maximum signal level of greater than 0.9g in the seismic band and sensor to sensor cross talk better than -70dB were achieved confirming the viability of this approach for optical seismic sensing.
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Passive seismic monitoring of microearthquakes in mines and hydrocarbon reservoirs
More LessNORSAR has developed and applied processing and interpretation software for microearthquakes in hydrocarbon reservoirs and mines. In this paper we will discuss the challenges and limitations of borehole installations compared to subsurface installations in mines with respect to data analyses and interpretation. Since 2003 we have been working with microseismic data from the 1.4 km deep Pyhäsalmi ore mine (Oye et al., 2006). The data are recorded using an ISS International (Integrated Seismic System) network consisting of 12 vertical and 6 three-component geophones deployed at depths between 1 and 1.4 km around the active part of the mine. The Pyhäsalmi mine and ISS have kindly made the raw seismic data available to us, which we are processing independently with in-house software (Oye and Roth, 2003). In hydrocarbon reservoirs, the most commonly applied geometry is an array of geophones that is lowered into a single borehole. We have primarily been working with data from an 18-day monitoring of the Ekofisk field in the North Sea and with various data from the San Andreas Fault Observatory at Depth (SAFOD) based on different receiver array configurations within Pilot Hole and Main Hole installation (Oye et al., 2004). In principal, event localization can be based on phase arrival times and polarization information, the latter being essential for single borehole installations only. However, the polarization is strongly affected by local heterogeneities, especially at the receiver site, and the reliability of polarization determination depends to a high degree on the geophone quality and on proper installation/orientation. Uncertainties of 10-20 deg are typical. An automatic estimation of basic source parameters such as e.g. seismic moment, seismically radiated energy and corner frequency, can generally be determined under the assumption of a theoretical source model (e.g., Oye et al., 2006). The signal spectra are corrected for propagation path effects such as geometrical spreading and attenuation and source spectra are fit to the corrected signal spectra. Amplitude effects from the source radiation pattern can only be compensated for if the fault plane solution is assumed known or by averaging, provided that the receivers have sufficient spatial coverage of the source. The spatial coverage of the source is even more indispensable to achieve reliable fault plane solutions, since the solution space is non-linear and ambiguous. The assignment of fault plane solutions already implies the assumption of a pure shear failure, which might not necessarily be the general case. To resolve for such non-shear or volumetric components in the source, a moment tensor inversion is required, which in turn relies on even better spatial coverage. Due to a generally superior 3D geophone configuration in mining environments compared to hydrocarbon reservoirs, the quantity and quality of results obtained from passive seismic monitoring are significantly higher. This becomes also evident when considering the amount of microseismic installations, which have been proven valuable, if not indispensable.
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Monitoring mining seismicity and hazard analysis, examples from Poland
By S. LasockiMany examples have shown that the activity accompanying underground mining works can be hazardous both to underground staff and mining installations, as well as to ground structures. Magnitude of the strongest seismic events in copper mines of Legnica-Glogow Copper District (LGCD) in Poland exceeds 4.0. Furthermore, due to shallow focal depth, events of this size can give rise to peak ground acceleration of more than 2 m/s2. An accurate assessment of seismic hazard posed by mining-induced events is thus a problem of primary importance. Monitoring mining seismicity in LGCD is carried on both underground as well as from the surface. The underground seismic network is supposed to provide information about seismic sources. Yearly several thousands events are recorded and parameterized. The surface accelerometric ground motion monitoring aims at assessing seismic impacts to buildings and other man-made structures in this considerably urbanized area. The mining seismic events are weak earthquakes but the seismicity in mines significantly differs from the earthquake process. Firstly, mining event occurrence is predominantly controlled by time-varying mining works, therefore the active zones in mines are, by their nature, transient. Moreover, even during their lifetime, the activity of these zones changes considerably. In our approach to seismic hazard assessment in mines, locations and times of activity of the zones that will be active in the future are deduced from programs of mining operations. Characteristics of fracturing process in these zones are inferred from characteristics of the zones that were active in the past and can be considered as models for the future activity. The model zones are selected by expert judgment based on anticipated similarity between mining and geologic conditions of the past and future zones. The epistemic uncertainty of such selections is considered within the logic tree scheme. Secondly, due to the heterogeneity of the rockmass fracturing process, the magnitude distribution of seismic events induced by exploitation is often non-Gutenberg-Richter's, complex and multimodal. As a remedy the model-free approach with the non-parametric kernel estimator of magnitude density is applied. This approach ensures reliable estimates of probability functions of event size regardless the actual complexity of the underlying distribution of magnitude. The mentioned ways of analyzing the seismic hazard posed by mining-induced seismicity are illustrated by a practical example in which we predict future seismic activity and estimate limiting values for ground motion in the 20 years horizon.
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Multidisciplinary monitoring at the Izaute gas storage geophysical laboratory
By F. AubertinIzaute is a gas storage facility operated by Total and located in the South West of France. The reservoir, at a depth of 500 m, is filled in the spring and extraction begins in the fall. This cycle is repeated on an annual basis. This site has been selected to be a geophysical laboratory for monitoring techniques due to this periodic behaviour and its easy access. A wealth of geophysical data both seismic (surface and borehole) and non-seismic has been acquired at Izaute on a permanent basis. In this presentation the various geometries used are described. Conclusions are drawn on the on the usefulness of the various techniques in monitoring the movements of the gas - water contact. In particular, the acquired experience has helped promoting downhole optical seismic sensors within more integrated monitoring configurations.
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Permanent reservoir monitoring using passive microseismic techniques
More LessIn the course of the last ten years the author and his colleagues have been responsible for the design and installation of many permanent passive microseismic monitoring systems for oil, gas and CO2 sequestration projects. Theses systems are typically designed to be Life of Field installations with an operating life for the downhole components predicted to be > 15 - 20 years. In all cases the systems are intended to provide operators with relevant information about the response of the reservoir and the surrounding strata, the behavior of existing or induced structural failures, and the performance of the subsurface infrastructure, i.e. injection, casings, production tubulars, etc. The paper discusses the design parameters and results from four projects and illustrates how permanent passive microseismic monitoring systems can be used to assist operators in their quest to maximize extraction from a reservoir and to assess the effectiveness of production enhancement techniques.
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SeisMovieTM: a continuous land seismic monitoring system
By J. J. PostelTo overcome the difficulties linked to source and surface noises in the near surface on 4D land seismic acquisition, CGGVeritas has developed a seismic monitoring technology called SeisMovieTM based on low-energy surface or buried sources operating continuously and simultaneously in conjunction with a network of permanent receivers' antennae. The antennae can be vertical when very high sensitivity is needed or horizontal when spatial information is necessary. As the sources and receivers are stationary and cemented, one of the major causes of non-repeatability (positioning and coupling differences) is removed. Furthermore, it was found that, unlike their surface counterpart, buried sources and buried receivers could be almost insensitive to weather changes and provide a far better repeatability. This system is fully automated and remotely controlled. This type of high-resolution seismic monitoring has the potential to optimize exploitation scenarios: tiny changes in the seismic response (a few microseconds and a few percent) can be measured and calibrated to direct reservoir measurements. On top of that, the SeisMovieTM technology allows active and passive seismic to be combined for continuous reservoir monitoring. We will present the results of a one month continuous experiment on a SAGD pilot site in Canada showing a high level of repeatability in an industrial context. The steam plant adjacent to the recording area and nearby drilling operations during this period did not prevent the system from being able to detect significant 4D seismic signals.
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Time lapse reservoir monitoring: geophysical applications from the geothermal industry
Authors D. Watts, D. Colombo, S. Hallinan and G. Nordquist and S. RejekiHigh enthalpy geothermal fields exploited for electricity production are routinely monitored using geophysics, including both the long term reservoir evolution and short term injection and interference tests. We present examples of induced micro-seismicity data, gravity and repeat levelling (ground subsidence) programs from some of the worlds most significant fields, including The Geysers in the US and Darajat in Indonesia. The evolution of reservoir mass balance is monitored through repeated, high precision levelling and gravity surveys, enhanced by simultaneous monitoring of ground water level changes in shallow boreholes. The mass balance tracks the ability of natural fluid recharge to keep up with net loss from production and only partial, condensed fluid re-injection. Accurate MEQ locations, obtained through iterative 3D tomographic modelling of Vp and Vs velocities and subsequent location updating, track production and injection fluid paths. Fluid characteristics can be monitored through spatial and temporal changes in the Vp/Vs ratio, and moment tensor analysis gives and indication of changing fracture systems. The rates of fluid movement associated with commercial geothermal production are of the same order of magnitude as those expected from large oil fields, suggesting the monitoring techniques are transferable. The fluid dynamics are somewhat different, naturally, but analogies such as steam and water flood monitoring are directly comparable.
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