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64th EAGE Conference & Exhibition
- Conference date: 27 May 2002 - 30 May 2002
- Location: Florence, Italy
- Published: 27 May 2002
61 - 80 of 688 results
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Amplitude-Preserving Monte Carlo 3D Prestack Migration
Authors L. Cazzola, M.T. Arienti, E. Bonomi and G. CardoneB-09 AMPLITUDE-PRESERVING MONTE CARLO 3D PRESTACK MIGRATION Abstract 1 We present an amplitude-preserving imaging condition based on a least-squares approach that applies to Monte Carlo wavefield migration methods. Its implementation requires the knowledge of the overall shot illumination map that can be computed at a negligible additional cost during the migration process. The resulting condition is not sensitive to instability effects usually plaguing other formulations. Furthermore it compensates irregular shot illumination and focusing/defocusing effect caused by the velocity field. Finally we show how the shot illumination volume is used as an independent tool for a better interpretation of seismic data.
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Pre-Stack Time Migration for Rough and Rugged Mountain Areas
More LessB-10 PRE-STACK TIME MIGRATION FOR ROUGH AND RUGGED MOUNTAIN AREAS Summary 1 Seismic imaging algorithms commonly used in production like NMO DMO pre-stack and post-stack migration are only applied to data that have been datumed to a planar surface. This is because conventional seismic imaging algorithms have an assumption that the shot and receiver of a seismic trace are located at the same elevation. This assumption is restrictive and cannot be satisfied in mountain areas with rough and rugged topography. There are two approaches to address this problem: wave-equation datuming or migration from topography. Here we developed a 3-D pre-stack
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Amplitude Preserving v(z) Pre-stack Kirchhoff Migration, Demigration and Modeling
Authors C. Notfors, Y. Zhang, M. Karazincir, J. Sun and B. HungB-11 AMPLITUDE PRESERVING V(Z) PRE-STACK KIRCHHOFF MIGRATION DEMIGRATION AND MODELING 1 Summary We analyze the true amplitude weights in time migration and demigration based on Bleistein’s Kirchhoff inversion and modeling formulas. In addition a geometrical spreading factor is derived for any dipping reflector in a v (z) medium. Finally we propose proper anti-aliasing formulas honoring sampling theory to preserve fidelity for 3-D migration and demigration. Introduction Kirchhoff prestack time migration is widely used in 3-D seismic data processing while Kirchhoff demigration is a useful tool to obtain a zero-offset data volume after Kirchhoff prestack time migration and stack. Arbitrary weights
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Wavefront Construction Kirchhoff Migration with Ray-Amplitude Corrections
Authors M.C. Fehler, S.T. Hildebrand, L.J. Huang and D.X. AldeB-12 Wavefront Construction Kirchhoff Migration with Ray-Amplitude Corrections 1 Michael C. Fehler Steven T. Hildebrand Lianjie Huang and Douglas Alde MS D443; Los Alamos National Laborartory; Los Alamos NM 87545; USA Summary: Kirchhoff migration using ray tracing travel times has been a popular imaging method for many years. However there are significant limitations in the ability of Kirchhoff migration to reliably image regions of complex structure when using only first arrivals. Thus new methods for imaging have been sought. One approach for improving imaging capability is to use ray tracing methods that allow the calculation of multiple-valued travel time tables
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Construction of Single-Valued Ray Field Maps in the Position/Angle Domain for Ray-Based Imaging with Multiple Arrivals
Authors D.A. Kraaijpoel, R.K. Snieder and K. Roy-ChowdhuryB-13 CONSTRUCTION OF SINGLE-VALUED RAY FIELD MAPS IN THE POSITION/ANGLE DOMAIN FOR RAY-BASED IMAGING WITH MULTIPLE ARRIVALS Summary DIRK KRAAIJPOEL 1 ROEL SNIEDER 2 and KABIR ROY-CHOWDHURY 1 1 Utrecht University Faculty of Earth Sciences Budapestlaan 4 3582 CD Utrecht The Netherlands 2 Center for Wave Phenomena and Dept. of Geophysics Colorado School of Mines Golden CO 80401-1887 USA We present a new approach to the representation and generation of ray field maps (traveltimes amplitude etc. ) for use in ray-based imaging techniques. For the new representation of ray field data we make use of the fact that the source
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Offset Plane Wave Migration
Authors D.J. Foster, C.C. Mosher and S. JinB-14 Offset Plane Wave Migration Abstract In spite of advances in computing hardware full aperture 3D pre-stack wave equation shot record migration of marine streamer data remains a significant challenge. Like common azimuth migration offset plane wave migration provides a means for reducing the number of computations required for full aperture wave equation imaging of azimuthally limited datasets. Offset plane wave migration algorithms are derived from common azimuth phase screen migrations by replacing the Fourier transforms over the offset coordinate with a stationary phase mapping between offset ray parameter in the wavenumber domain and offset in the space domain. This
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3D Zero Offset-Common Reflection Surface Stack for Land Data - Real Data Example
Authors P. Marchetti, A. Cristini and G. CardoneB-15 3D ZERO-OFFSET COMMON REFLECTION SURFACE STACK FOR LAND DATA - REAL DATA EXAMPLE 1 ANTONIO CRISTINI 1 GIOVANNI CARDONE 1 and PAOLO MARCHETTI 2 Summary. The macro-model independent Zero-Offset Common Reflection Surface stacking technique has been established as an improvement of the conventional NMO/DMO processing. Over the past years it has been successfully applied both to 2D synthetic and real multi-coverage data and only recently a 3D implementation was developed and tested on a synthetic data set. We present and discuss an implementation of the CRS stack that applies to 3D real data. The first satisfactory results on a
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Improved Resolution in Time and Depth Processing by Macro-Model Independent CRS Stacking
Authors G. Gierse, H. Trappe and J. PruessmannB-16 Improved resolution in time and depth processing by macro-model independent CRS stacking H. Trappe G. Gierse and J. Pruessmann TEEC Trappe Erdoel Erdgas Consultant Burgwedeler Str. 89 30916 Isernhagen Germany Macro-model independent imaging techniques have received increasing attention in seismic exploration in recent years. Based on this technical strategy the Common-Reflection-Surface (CRS) method has proved to be a valid alternative to conventional NMO/DMO processing. Numerous application examples demonstrate the increase in resolution by this technique. The superior signal-to-noise ratio and reflector continuity are supplemented by an enhanced imaging of structural details and dipping elements. Both these imaging advantages and
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Local Imaging Approach and Applications
Authors I. Lecomte, L.-J. Gelius and S.-E. HamranB-17 LOCAL IMAGING APPROACH AND APPLICATIONS Summary 1 Local imaging obtained using a local plane-wavenumber approach of Generalized Diffraction Tomography is very similar to Synthetic Aperture Radar imaging in spotlight-mode acquisition. A local image of the scattering structures around any point in a model is calculated using ray-based Green’s functions computed at that point only. The cost of the local imaging is very small compared to classic imaging which needs grids of Green’s functions. The signal-processing approach inherent to this FFT-based local imaging allows also a very powerful and flexible imaging with full control of aliasing and noise filtering. The
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Constrained Least-Squares Wave-Equation Migration for AVP Inversion
Authors H. Kuehl and M.D. SacchiB-18 CONSTRAINED LEAST-SQUARES WAVE- EQUATION MIGRATION FOR AVP INVERSION Abstract 1 Wave-equation migration is known to be beneficial for structural imaging in complex geological settings. Recently imaging principles have been developed that allow for the extraction of amplitude variations as a function of angle or offset ray-parameter (AVA or AVP) from the downward continued wavefield. We propose the least-squares (LS) approach to wave-equation migration in order to generate high quality AVP common image gathers (CIGs). As we have previously demonstrated with the Marmousi dataset least-squares imaging with a smoothing constraint on the AVP CIGs can mitigate artifacts. Here we study
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SIGSBEE_2A Synthetic Subsalt Dataset - Image Quality as Function of Migration Algorithm and Velocity Model Error
Authors J. Paffenholz, J. Stefani, B. McLain and K. BishopB-19 SIGSBEE_2A SYNTHETIC SUBSALT DATASET - IMAGE QUALITY AS FUNCTION OF MIGRATION ALGORITHM AND VELOCITY MODEL ERROR 1 Summary Producing consistent production-quality seismic images sub-salt within the deepwater Sigsbee escarpment province of the Gulf of Mexico remains today an unsolved technical challenge. To help gain insight into the imaging failure mechanism(s) and to facilitate research into potential imaging solutions the SMAART JV constructed a 2D model containing a distorting salt lens and calculated a 2D acoustic Finite Difference numeric dataset. This dataset was used to investigate a) the relationship between imaging algorithms and 2D sub-salt image quality and b) the
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Imaging the Unimaginable
Authors A.J. Deighan, H. Crook and R. BlowB-20 IMAGING THE UNIMAGINABLE Introduction 1 Even as a mature area the Southern North Sea presents one of the most challenging areas for Prestack Depth Migration (PreSDM). Constrained by project schedules and costs we present a case history where we have integrated ambiguous borehole and seismic data in a structurally complex area resulting in significant changes to the geological interpretation. General geological setting The area of interest lies in the Dowsing Fault Zone (DFZ) on the western margin of the Southern North Sea. The northeasterly dipping fault zone separates the relatively stable East Midlands shelf from the tectonically active Sole
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Pre-Stack Depth Migration Netherlands an Integrated Methodology - Processing, Interpretation, Algorithm Development
Authors G. Desrousseaux, L. Lemaistre, P. Sexton and P. WilliamsonB-21 PRE-STACK DEPTH MIGRATION NETHERLANDS - AN INTEGRATED METHODOLOGY PROCESSING INTERPRETATION ALGORITHM DEVELOPMENT Introduction 1 A 3D Pre-Stack Depth Migration (PSDM) has been carried out on a Netherlands block case study with the aim of improving the imaging and minimising the structural uncertainty. The prospect is in a structurally complex environment beneath a 3000m high salt diapir. The sensitivity of PSDM to the input velocity model is well understood. In previous publications [5] we have proposed adaptations of tomographic model building techniques to deal with complex tectonics. In this paper we would like to focus more on the importance and
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Angle Tomography
Authors S. Brandsberg-Dahl, B. Ursin and M.V. de HoopB-22 ANGLETOMOGRAPHY SVERRE BRANDSBERG-DAHL 1 BJORN URSIN 2 and MAARTEN V. DE HOOP 3 1 BPAmerica Inc. Houston TX 77079 USA. Formerly: Colorado School of Mines Golden CO80401 USA 2 Norwegian University of Science and Technology N-7491 Trondheim Norway 3 Center for Wave Phenomena Colorado School of Mines Golden CO80401 USA Abstract Wepresent amethod for migration velocity analysis in complex media that does not depend on picking traveltime misfits or residual moveout in common image gathers (CIGs). Our method constructs CIGs in the scattering-angle/azimuth domain where we apply semblance or differential semblance to measure the coherency of events. Since amplitude
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A Comparison of Ray-Based and Waveform Tomography - Implications for Migration
Authors R.G. Pratt, F. Gao, C. Zelt and A. LevanderB-23 A comparison of ray-based and waveform tomography: implications for migration Introduction 1 Seismic ray-based tomography has proven to be an effective imaging tool in many applications. More recently the technique of waveform tomography has emerged in which we use wave-theoretical methods and the direct arrival waveform. The distinctions that arise in tomography are an analogue for the distinctions between ray-based (Kirchhoff) methods and “wave-equation” methods used in migration: in most implementations of ray-based tomography (and Kirchhoff migration) events are assumed to be adequately represented by their (single valued) arrival times while a wave-theoretical approach treats the wavefield as a
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Toward Accurate Velocity Models by 3D Tomographic Velocity Analysis
More LessB-24 TOWARDS ACCURATE VELOCITY MODELS BY 3D TOMOGRAPHIC VELOCITY ANALYSIS Summary 3-D prestack depth migration has become a routine process for depth imaging. However the image quality depends strongly on the accuracy of the velocity model. For post-migration tomographic analysis bad data (picks) null space and intrinsic non-linearity may degrade the quality of the velocity model. In our tomography implementation we use several tools to address these problems. First we automatically pick a large number of depth residuals without requiring lateral continuity along horizons. In the solver we apply a left preconditioning operator resulting from the L norm to reduce
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Defining Lateral Velocity Variations to Improve Reservoir Mapping with New Seismic Measurements while Drilling, Leadon Field, UK
Authors S.J. Bevali, P.T. King, G. Templeton and M.L. ReederB-25 DEFINING LATERAL VELOCITY VARIATIONS TO IMPROVE RESERVOIR MAPPING WITH NEW SEISMIC MEASUREMENTS WHILE DRILLING LEADON FIELD UK Abstract 1 PHILIP KING 1 GERHARD TEMPLETON 1 MARK REEDER 1 and STEPHANE BEVALI 2 1 Kerr-McGee North Sea (U.K.) Ltd 2 Schlumberger Kirkton Avenue Aberdeen AB21 0BF UK During velocity model building of the Leadon field Kerr-McGee had recognized lateral velocity variations. However it has proved difficult to model and integrate the uncertainties associated with these velocity variations particularly in planning long horizontal development wells (up to 5000 ft MD). The present article illustrates how we used the new Seismic Measurement
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Comparison of Full Waveform SeismicMWD and Conventional VSP Data from the South Caspian
Authors J.B.U. Haldorsen, M. Krasovec, S. Raikes, T. Harrold, D.N. Day and J.D. ClippardB026 Comparison of Full Waveform SeismicMWD and conventional VSP data from the South Caspian 1 J.B.U. Haldorsen 1 M. Krasovec 2 S. Raikes 3 T. Harrold 3 and D.N. Day 3 J.D. Clippard 4 1 Schlumberger-Doll Research Old Quarry Road Ridgefield CT06877-4108 USA 2 Earth Resources Laboratory Massachusetts Institute of Technology 42 Carleton St. Cambridge MA 02142 3 BP Chertsey Road Sunbury on Thames Middlesex TW16 7LN UK 4 Shell E&P Technology Appl. & Research Volmerlaan 8 Postbus 60 2280AB Rijswijk The Netherlands Abstract We demonstrate that full waveform data acquired while drilling using the new Schlumberger Seismic Measurement While
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A Migration Method for Limited Seismic Array Geometries - Application to Reverse VSP
Authors M.L. Krasovec, W. Rodi, R. Turpening, R.T. Coates and M.N. ToksözB-27 A MIGRATION METHOD FOR LIMITED SEISMIC ARRAY GEOMETRIES - APPLICATION TO REVERSE VSP Summary 1 Images produced from seismic data collected with limited arrays such as downhole seismics or surface seismics with incomplete arrays tend to contain artifacts resembling migration smiles. These artifacts are often suppressed by severely limiting the migration dip aperture which can also omit dipping reflectors and detract from the quality and usefulness of the image. To maximize the imaging capabilities of such datasets a new imaging approach has been developed to compliment conventional migration methods. The new approach termed vector image isochron (VII) migration minimizes
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Planning, Acquiring and Processing a Walkaround VSP for Fracture Induced Anisotropy
Authors S.A. Horne, C. Thompson, R. Moran, J. Walsh, J. Hyde and E. LuiB-28 PLANNING ACQUIRING AND PROCESSING A WALKAROUND VSP FOR FRACTURE INDUCED ANISOTROPY 1 Introduction The Rangely field Western Colorado is a large monoclinal structure with gentle dips of less than 4 degrees at the reservoir depth of approximately 1.7km. The principal reservoir rock is the lower Pennsylvanian Weber formation which is a massive fine-grained aeolian sandstone exhibiting cross-bedding. The Weber formation is mostly overlain by shales with some sandstones. Rangely is a mature field discovered in 1933. Since initial production in the 1940s the field has undergone pressure depletion followed by water injection and now CO2 miscible flood. Injector-producer pattern
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