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60th EAGE Conference and Exhibition
- Conference date: 08 Jun 1998 - 12 Jun 1998
- Location: Leipzig, Germany
- ISBN: 978-90-73781-09-2
- Published: 08 June 1998
201 - 250 of 489 results
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Requirements for a Three-Component Downhole Frequency Electromagnetic System for Mineral Exploration
Authors B. Bourgeois, C. Alayrac and H. SoininenAs the search for metallic ores is going deeper, it becomes more important to use efficient geophysical tools allowing investigations at some distance from bareholes.
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Recent Advances in Borehole Resistivity Logging
Authors K. -M. Strack, O. N. Fanini, A. G. Mezzatesta and L. A. TabarovskyIn locating liydrocarbons in a borehole, electrical logging techniques play a key role since they can distinguish between oil and water saturated rocks.
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The Parabolic Radon Transform - Least-Squares Solutions and Error Analysis
By E. MaelandLeast-squares solutions are widely used in seismic data-processing (Eines and Treitel,1984), but no systematic analysis of the errors are given in the literature.
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Impact of Surface Consistent Deconvolution on Wavelet Stability and Seismic Attributes - a Case Story
Authors A. Prakash, V. Singh, U. C. Saxena and G. SenThe prime goal of seismic interpretation is to extract more information out of processed seismic data and utilise it for interpreting subsurface structural, stratigraphic and lithologic features .
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Using the BPNN as a General Feature Detector
Authors H. C. Dai, C. MacBeth and X. Y. LiIn earthquake seismology and exploration seismology, a major step is often the detection of characteristic features from the seismic traces as a basis for further interpretation and analysis.
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Relative Amplitude Processing - a Contractor Evaluation
By A. BulandHistorically, the ultimate goal of seismic processing has been a migrated stack. An image with well balanced amplitudes and clean sharp interfaces has made the basis for structural interpretation and reservoir delineation.
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Optimum Primary and Additional Signals Maximizing the Resolution of Seismic Record
More LessUsually in practice, while generating seismic waves under constant conditions numerous natural and technical obstacles erevent acquisition of the reflecting seismograms with sufficiently wide spectral interval within the limits of which signal predominates over noise.
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A Hybrid fk Filter for VSP Wavefield Separation
Authors A. Dasios, J. S. Oliver and C. McCannEstimates of anelastic attenuation from vertical seismic profiles (VSP) normally use the downgoing wave arrivals. Unless the geology of the survey area is very simple, any window chosen around the direct arrivals (downgoing wavefield) is likely to contain a significant amount of upgoing energy, leading to distortion of the downgoing wave spectra. As attenuation measurements are based on the spectral properties of the seismic data, they are very sensitive to the methods used for wavefield separation if these distort the remaining downgoing wavefield.
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High Resolution Time Frequency Filtering of Surface Waves
By T. StöckerTime-frequency filtering can be used to remove non-stationary components - especially surface waves - from seismic signals. The classical concept to perform this is Gabor analysis. Here we present a different method which uses Wigner -Ville analysis and time-frequency-atomic signal decompositions .
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Using a Recognition Technique for S/N Enhancement of Deep Seismic Reflection Data
Authors M. Van der Baan and A. PaulRecognition techniques are widely spread in remote sensing image processing to separate the different signal types in a semi- or fully automatic way, thereby saving immense interpretation time.
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CMP Processing and Single Scattering
Authors T. Jäger, C. Müller and B. MilkereitConventional CMP seismic data processing has evolved over the decades to become a sophisticated methodology designed to enhance continious reflectors in the subsurface. Many of the inherent assumptions begin to break down for the scenarios relevant to small scattering bodies.
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Identifying Tuning Effects in AVO Responses
Authors A. Castoro, R. E. White and R. D. ThomasSummary not available
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Reflection Coefficients for Elastic Media with a System of Vertical Fractures
Authors M. Zillmer, D. Gajewski and B. M. KashtanAn isotropic elastic medium with a single system of parallel fractures or microcracks serves as a reservoir model. It can be represented by an equivalent transversely isotropic medium with symmetry axis normal to the fracture planes (Hudson 1981, Schoenberg & Douma 1988).
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AVO-Investigations on Shallow Marine Sediments
Authors M. Riedel and F. TheilenAVO (Amplitude Versus Offset) - investigations of the seafloor, which are well known in the reservoir characterization in hydrocarbon prospecting, are used for investigations of shallow marine environments with respect to physical properties and distribution of sediments. Parameters of interest are P- and S- Wave velocities, bulk density and related geotechnical properties, which can be used for the characterization of environmental and offshore engineering problems. In the North Sea and Baltic Sea, we have conducted high resolution multichannel seismic measurements with boomer and sparker as seismic sources.
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Comparison of Shallow P- and S-Wave Seismic at the Huesca Fluvial Fan System in Spain
Authors M. H. Van Kempen, G. G. Drijkoningen, V. Nijhof, T. ter Burg and K. Roy-ChowdhurryIn an area surrounded by magnificent outcrops, various seismic studies were carried out to image land bodies down to 160 m depth.
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The Effect of Multiple Removal on AVO Analysis - a Gulf of Mexico Data Example
Authors R. Van Borselen, P. Sen and M. LahrRemoval of free surface multiples from seismic reflection data is an essential pre-processing step before pre-stack migration and post-migration amplitude analysis. In this abstract, the effect of different multiple removal techniques on amplitude versus offset (AVO) analysis is investigated.
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AVO Attributes from Multicomponent Ocean Bottom Seismic Data
More LessWe present a method to compute P-P and P-S AVO attributes from the vertical and horizontal components of the particle velocity measured at the sea bottom.
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Using of the New Seismic Methods for Determination of Minor Faults in Marineza Oilfield
Authors L. Çobo and L. MehillkaMarineza oil field extends partly in the northern of the Kurveleshi Belt and in the southern part of the Pen- Adriatic Depression. From the geological point of view, this field includes the Messinian deposits that are unconformable with carbonate deposits.
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Reservoir Monitoring Using Non Conventional Seismic Surveying
Authors J. Meunier, F. Huguet and M. BecqueyThe Céré-la-Ronde artificial gas storage reservoir was used by GAZ DE FRANCE to evaluate seismic monitoring methods. Conventional surveying was performed before and after gas injection and was able to show the effect of injecting gas in a water-filled reservoir.
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Time-Lapse 9C Combined Borehole and Surface Seismic Data Acquisition for Reservoir Studies
Authors R. D. Benson, A. Takla and R. MonganResearch is currently underway using time-lapse seismic surveys to monitor the dynamic characteristics of oil reservoirs.
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Progressive Prestack Cross Equalization of Time-Lapse Seismic Data - a North Sea Case Study
By P. HarrisThe main aim in time lapse seismic is to analyse changes in seismic response due to fluid movement, stress changes and temperature changes in the reservoir.
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Comparison of Two Different Crossline Migration Methods for 3D Prestack Migration
Authors T. Gindler and D. RistowFull 3-D prestack depth migration (one-pass migration) is in principle an effective way to image complex 3-D structures with significant lateral vetocity variations.
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Migration of VSP Data in Presence of Lateral Velocity Changes
Authors N. Y. Marmalevsky, Z. V. Gomyak, Y. V. Roganov and A. L. KhankinPicking and spatial localization of steep dipped reflectors is now one of the most important problems when studying complex medium, in particular, a side walls of salt stock, "fonts" of stock, tectonic dislocation planes, steep dipped layer boundaries, etc.
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Analysis of Errors in Constant Velocity Viscoacoustic Migration
More LessMigration images are sensitive to errors in the velocity macromodel. To analyze the effects of velocity errors, we derive analytical formulae of the image of a horizontal plane reflector in a homogeneous macromodel, obtained by migration with an incorrect velocity. We let the velocities be complex and frequency dependent (viscoacoustic model), so that the analysis also describes the effects of errors in the attenuation macromodel.
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Reflection Coefficient Determination Using Eigenwavefront Attributes
Authors J. C. R. Cruz, G. Garabito and J. UrbanIn this paper the reflection coefficient map is obtained applying a geometrical spreading correction factor to the principal component of the primary reflection wavefields, corresponding to seismic traces into zero-offset configuration data.
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Imaging of Scattering Objects by Means of Adaptive Focusing Transformations
Authors V. A. Pozdniakov, V. I. Kostin and D. SafonovThe physical background of focusing transformations is the diffractive model of geological media, when it is treated as a set of diffractive points, so any wave field can be thaught as a superposition of diffracted waves.
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Integral Dip Move Out Operator for Transversely Isotropic Media - the Hyperbolic Case
By A. StovasThe methods which takes into account the anisotropy for the transversely isotropic models with a vertical symmetry axis (VTI media) were developed in the recent years.
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Robust Tomography Algorithms
Authors M. Dobróka, M. Kis and A. C. KovacsThe noise contained by the data set has an important effect to the accuracy of the tomographic reconstruction.
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Aperture for 3D Seismic Imaging
More LessImaging in reflection seismology is based on backward wave field extrapolation (migration).
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Multiple Attenuation - a Contractor Evaluation
Authors A. S. Pedersen, L. Amundsen, S. Johansen, O. R. Lorentsen and B. ArntsenSix geophysical contractars have been invited to apply their best multiple suppression technology on a seismic data set prepared by Statoil Research.
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Identification of Surface Related Multiples Using Wavefront Characteristics
More LessWe propose a method for the identification of surface related multiple reflected events from prestack data.
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Trigger Time Synchronization in Shallow Seismic Exploration
By R. SunAn algorithm to synchronize the trigger time in high-resolution reflection shallow seismic data is developed.
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Interactive Two-Way Source Wavelet Estimation from Marine Seismic Data
By R. Alá‘iIn this paper an example is illustrated on a marine dataset from the North Viking Graben in the North Sea. In this example, a method is presented in which source wavelets can be estimated interactively from marine surface data with all multiples included, taking all the boundary conditions at the seabottom into account, using two-way techniques.
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Decomposition of Multicomponent Sea Floor Data into Primary PP, PS, SP and SS Wave Responses
Authors E. Holvik and L. AmundsenThe sources in land data acquisition are normally vibrators or buried dynamite. Using vibrators, it is in principe possible to perform a 3 x 3 or "nine-component" seismic survey.
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Multiple Attenuation and P/S Splitting of OBC Data at a Heterogeneous Sea Floor
Authors L. Amundsen, L. T. Ikelle and J. MartinAfter several attempts through the 80's, the technologies for recording seismic data directly on the sea floor are now well established.
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Evaluation of the Surface Related Multiple Elimination Applied to Field Data
Authors P. L. A. Winthaegen, B. C. Scheffers and D. J. VerschuurAfter seismic surveying multiple energy may interfere with primary reflections. Mapped in a certain domain, the discrimination of unwanted multiples can be optimally performed if there is no interference with primaries, and, hence, no distortion of the primaries after elimination of the rnultiples.
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Free Surface Boundary Conditions for Elastic Staggered-Grid Modelling Schemes
By R. MittetThe purpose of the work presented here is to describe an accurate and simple implementation of the clastic free surface for staggered grid modeling schemes. An analysis for acoustic waves demonstrates that a horizontal free surface can be implemented using two methods. One method give the free surface on the main node system in a staggered grid scheme, the other method give the free surface midway between nodes. Both methods are utilized when implementing the elastic free surface on a staggered grid. The proposed scheme show excellent agreement with a direct global matrix method.
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S Wave Depth Section as a ByProduct of Deep Reflection Profiling
Authors E. Törös, L. Hermann and Z. PrónayThe knowledge of the S-velocity structure is very important for geotechnical and earthqualce engineering. Direct measurements using downhole/crosshole methods are accurate but give only local information and are very expensive. In loose sediments the borehole S-velocity determination methods fall down. The S-refraction/ reflection methods give less accurate information (e.g. on important low velocity layers embedded) with relatively high costs.
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Wavefield Inversion of Reflection Data - Recovering High and Low Wavenumbers with Local Methods
Authors G. Hicks and R. G. PrattA common limitation of seismic waveform inversion of reflection data is that standard iterative methods recover only high wavenumbers (corresponding to seismic frequencies), resulting in migration-like velocity images.
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Interal Seismic Structure of Flood Basalts
Authors M. M. Fliedner, J. R. Smallwood, J. Frühn and R. S. WhiteSeaward dipping reflector sequences on volcanic passive margins are known from drilling to originate from thick piles of subaerial basalt flows. Individual flows are typically much thinner than the seismic wavelength; it is therefore not immediately obvious what exactly gives rise to the observed reflections.
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P-Wave Reflections in 3D Model of Coal Basin with Boulders
By V. BuchaThis paper is devoted to the computation of reflections in 3-D model of coal basin with four boulders located in the upper bed of the Goal seam.
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Anisotropy from a Hybrid Optimization Method with Wide-Angle Seismic Data
More LessThere is a large body of evidence supporting the existence of widespread seismic anisotropy at all scales. The determination of anisotropy parameters is essential for accurate seismic imaging and lithological identification.
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Separation of Up- and Downgoing Waves Using the BIE Method
Authors A. Druzhinin and M. Turhan-TanerThis paper follows recent techniques for decomposing, sea-floor measurements unto up- and downgoing waves.
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Full 3D Stratigraphic Inversions toward an Accurate Reservoir Imaging
More LessThe integration in 3D of seismic and geological data is crucial to ensure accurate and reliable reservoir studies.
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