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63rd EAGE Conference & Exhibition
- Conference date: 11 Jun 2001 - 15 Jun 2001
- Location: Amsterdam, Netherlands
- Published: 11 June 2001
301 - 400 of 516 results
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EM Frequency and Time Characteristics of Complex Polarizable Media
By A.A. RyjovP048 EM FREQUENCY AND TIME CHARACTERISTICS OF COMPLEX POLARIZABLE MEDIA ALBERT A. RYJOV 1 The study of EM frequency and time responses of polarizable electrochemically active environment in many respects depends on applied instrumentation and measuring technology. The great importance for this study has an idealized representation of the investigator about a view of the frequency or transient characteristics of complex medium. Frequency response of complex medium is understood as dependence of observed amplitudes and phases from frequency at a set of specific electrode spacings of EM array above horizontally layered or 3D medium. Time response is understood as dependence
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A New Method for the Interpretation of Induced Polarization Data - the TAU-Transform Approach
Authors E. Turai and M. DobrókaP049 A NEW METHOD FOR THE INTERPRETATION OF INDUCED POLARIZATION DATA – THE TAU-TRANSFORM APPROACH E. TURAI and M. DOBRÓKA University of Miskolc Department of Geophysics 3515 Miskolc Egyetemváros Hungary Summary 1 In the paper the TAU-transform method is introduced for the determination of the timeconstant spectrum of the polarizability curves received by time-domain IP measurements. An easy and quick inversion algorithm is also presented for practical use. Some results of the interpretation of field data collected over Hungarian waste sites are shown in case histories and – based on the time-coefficient spectra- the characterisation of the main components of
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Source Polarization Effect in Case of Elongated Surface Inhomogeneities Covering Transition Zone
More LessP050 SOURCE POLARIZATION EFFECT IN CASE OF ELONGATED SURFACE INHOMOGENEITIES COVERING TRANSITION ZONE G. PETHŐ 1 and L. FICSÓR 2 Introduction 1 Practical CSAMT measurements are frequently made not only in the far-field zone but also in transition regime. For homogeneous earth there is a relatively smooth transition from far-field to near-field behavior. In nonhomogeneous environments this transition zone behavior becomes complex and depends upon the type of configuration separation and resistivity distribution. Special attention has to be made to resistive basement overlaid by conductive layer model which supports the reduction of plane-wave regime (Wannamaker 1997). The aim of this
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Geophysical Characterization of the Etla Valley Aquifer, Oaxaca, Mexico
Authors R.E. Chavez, E.L. Flores-Marquez, A. Tejero and M.E. CamaraP051 GEOPHYSICAL CHARACTERIZATION OF THE ETLA VALLEY AQUIFER OAXACA MEXICO Abstract In the last 40 years water supply in the main Mexican cities has increased since the urban population rate and the industrial and agricultural needs are growing up. Oaxaca City the capital of the state Oaxaca in the southwestern portion of Mexico is one of such examples. The main aquifer is located to the NW of the State’s Capital within the Valley of Etla. This produces 80% of water used in agriculture industry and human consume in the whole state. Gravity data interpretation allowed inferring the 2-D geometry of
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A Network Based MT Data Processing System
Authors H. Lee, B.-D. Kwon, H. Chung, O.S. Hoon and Y. SongP052 A NETWORK BASED MT DATA PROCESSING SYSTEM Summary 1 We developed a network based MT (magnetotelluric) data processing server/client system using the socket and distributed programming environment. In this server/client system socket communication and RMI (Remote Method Invocation) technology were adopted to produce an effective and practical client application. The Java technology provided facilities to develop the network based system. Since the MT data processing and inversion require heavy computational capability MPI (Message Passing Interface) parallel processing technique was adopted to help the effective controlling and upgrading of the programming codes. Since this system can be accessed by lots
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Approximate Joint Inversion of MT and DC Geoelectric Data in Case of 2D Structures
Authors M. Dobróka, M. Kis and E. TuraiP053 APPROXIMATE JOINT INVERSION OF MT AND DC GEO-ELECTRIC DATA IN CASE OF 2D STRUCTURES M. DOBRÓKA 1 M. KIS 2 and E. TURAI 1 Summary 1 Using the Generalized Series Expansion method an inversion algorithm is proposed for the processing of DC and MT data measured above 2D structures. In the algorithm approximate forward modeling is applied with the parameters of the locally 1D model. It is shown that GSE inversion gives highly acceptable estimate for the laterally changing parameters of the model. Introduction In the geoelectric exploration of the earth structures magnetotelluric and DC methods are traditionally applied.
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A.C. Electrical Properties of Kolinite under Pressure-Pseudo Random Network Modeling
Authors M.M. Gomaa, S.A. Hussain, E.A. El-Diwany, A.E.R.E. Bayoumi and M.M. GhobashyP054 A. C. ELECTRICAL PROPERTIES OF KOLINITE UNDER PRESSURE- PSEUDO RANDOM NETWORK MODELING Abstract 1 Few observations have been reported for the effects of pressure on the complex resistivity of rocks. The purpose of our study is to try to fit experimental data for kaolinite samples under a pressure up to ≈ 4. 5Kbar and ≈ 50% atmospheric relative humidity in the frequency range 10 Hz using a pseudo- random network model based on the renormalization group method. The model used for the grains is composed of surface impedance on the kaolinite grain surface due to the presence of water
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Resistivity Imaging of Great Mass Movements - Two Examples from Northeastern Italy
Authors G. Santarato, N. Abu-Zeid, M. Bacchini, E. Gaspari, L. Salti and A. ZannoniP055 RESISTIVITY IMAGING OF GREAT MASS MOVEMENTS – TWO EXAMPLES FROM NORTHEASTERN ITALY Abstract 1 In the present work the results of a large geophysical survey using electrical resistance tomography (ERT) technique carried out over two different mass movements in Northeastern Italy will be presented and discussed. At one site the internal structure of a large debris flow has been investigated while in the other the depth to the slipping surface was estimated. The depths in hand exceeded one hundred meters below the ground surface; despite this the resolution of the method was sufficient to achieve relevant information not only
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3D Prestack Depth Migration Using Generalized Screen Propagators
More LessP061 3D PRESTACK DEPTH MIGRATION USING GENERALIZED SCREEN PROPAGATORS Summary The generalized screen propagator (GSP) is a one-way wave equation based wide-angle wave propagator. It can be used for high quality imaging in complex geological structures. Algorithms for both shot-domain and offset- domain data set have been developed. In this paper the advantages of the GSP are briefly reviewed. 3D prestack depth migration examples using synthetic land and marine data sets are presented. Introduction The phase screen method (split-step Fourier method) is based on the one way wave propagation theory. It can be used as a fast propagator for seismic
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Demonstration of 3D Preserved Amplitude PsDM and AVA Relevance
Authors R.M. Baina, H. Calandra and P. ThierryP-062 DEMONSTRATION OF 3-D PRESERVED AMPLITUDE PSDM & AVA RELEVANCE R. M. BAINA 1 H. CALANDRA 2 and P. THIERRY 3 1 Ipedex detached to École des Mines de Paris 2 TotalFinaElf av. Larribau F-64018 Pau 3 École des Mines de Paris 35 rue Saint Honoré F- 77 305 Fontainebleau Summary. Preserved amplitude processing is now considered as a valuable tool for quantitative discrimination of lithologies and fluids in hydrocarbon reservoirs. Since industrial and real sized applications required accurate and efficient tools we present here a 3D synthetic example to show up to what point the amplitude information contained in
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What to Expect from Prestack Time Migration
More LessP063 WHAT TO EXPECT FROM PRESTACK TIME MIGRATION WALTER E. A. RIETVELD 1 BP – UTG Geophysics Chertsey Road Sunbury on Thames UK Abstract This paper attempts to shed light on the expected quality of prestack time migration. Prestack time migration has become a widely used tool in areas where we have slowly varying lateral velocities and good stratigraphic imaging is required. We will show that for low vertical velocity gradients prestack time migration will yield very accurate images of the subsurface. For stronger vertical gradients the longer offsets show residual move-out even if the correct velocities are used. At
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To Image in Depth or in Time? That is the question
Authors M. Goodwin and M. SugrueP064 TO IMAGE IN DEPTH OR IN TIME? THAT IS THE QUESTION MIKE GOODWIN and MICK SUGRUE GX Technology EAME Ltd. Lawrence House 45 High Street Egham Surrey TW20 9DP UK Introduction 1 Prestack depth migration (PSDM) is employed by many oil companies to address a host of seismic imaging challenges associated with complex geologic conditions such as steep structural dips rapid lateral velocity variations and undulating surface topography. However there are many cases where prestack time migration (PSTM) either zero-offset or full Kirchhoff finite-offset might be sufficient for simpler imaging problems or where the additional cost and time required
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True-Amplitude Common-Offset, Common-Azimuth v(z) Migration
More LessP066 TRUE-AMPLITUDE COMMON-OFFSET COMMON-AZIMUTH V(Z) MIGRATION 1 YU ZHANG 1 SAMUEL H. GRAY 2 and JERRY YOUNG 1 1 Veritas DGC Inc. 10300 Town Park Drive Houston TX 77072 USA 2 Veritas DGC Inc. Calgary Summary We investigate the amplitude behavior of nonzero-offset phase-shift migration in two and three dimensions. By transforming phase-shift migration into an equivalent Kirchhoff migration we find the deviation of the phase-shift migration operator from “true-amplitude.” We also investigate the amplitude error introduced by anti-aliasing for both phase-shift and Kirchhoff migration. Even for fairly routine acquisition characteristics this amplitude error can dominate the error due to
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The Limitations of Time Migration and Trace Stretch in the Presence of Lateral Velocity Gradients
More Less1 P067 THE LIMITATIONS OF TIME MIGRATION AND TRACE STRETCH IN THE PRESENCE OF LATERAL VELOCITY GRADIENTS S. KELLY and J. REN Summary This paper quantifies the imaging errors that result from the assumptions of time migration and a preliminary laterally-variable “stretch” of the data in the presence of lateral velocity gradients. The analysis is restricted to media that are approximately homogeneous in the vertical direction with dip in the same direction as for the velocity gradient. It is shown that a time migration that explicitly recognizes the lateral variation in velocity results in underestimation of steep dips by only
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Automatic and Continuous Image Gather Analysis after Pre-Stack Depth Migration
Authors L. Lemaistre, C. Hanitzsch and A. LehecP068 AUTOMATIC AND CONTINUOUS IMAGE GATHER ANALYSIS AFTER PRE-STACK DEPTH MIGRATION LAURENT LEMAISTRE CHRISTIAN HANITZSCH and ANNE LEHEC Introduction 1 Pre-stack depth migration (Pre-SDM) becomes a conventional tool in seismic processing. Pre- SDM is used mainly when time processing assumptions are no longer valid for example in structured zones with strong velocity variations. As the quality of Pre-SDM result is very sensitive to the accuracy of the input velocity model the control and the validation (QC) of the input velocity model become essential in the Pre-SDM processing sequence. We present an innovative and fast method which allows the processing geophysicist
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Depth Estimation Using a Calibrated Regional Linear Velocity Model - Field Matzen, Vienna Basin
Authors K. Millahn, K. Resch and E. StröblP069 DEPTH ESTIMATION USING A CALIBRATED REGIONAL LINEAR VELOCITY MODEL – FIELD MATZEN VIENNA BASIN K. RESCH 1 E. STRÖBL 2 and K. MILLAHN 1 Summary A regional velocity-depth model of the central area of the Vienna Basin has been developed based on borehole seismic data (26 check shots and VSP surveys) and DMO velocities of a 3D seismic survey (20 by 30 km 2 ). Both velocity functions interval velocity V as well as DMO velocity (VDMO) can be reliably approximated by a linear model V(Z) = V0 + kf * Z down to a maximum basin depth of
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Depth Imaging and Velocity Analysis - Case Study of Yamburg Gas Field
Authors R.M. Gataulin, Y.R. Adiev, G.Z. Valeev and G.G. KhalilovP070 DEPTH IMAGING AND VELOCITY ANALYSIS – CASE STUDY OF YAMBURG GAS FIELD Summary 1 The aim of this paper is to show the results of a prestack depth migration study and velocity analysis in the Yamburg gas field region. The dome-shaped Yamburg structure is an apparent inversion zone in which seismic reflectors corresponding to Cretaceous sediments lay discordantly on Jurassic-Triassic-Paleozoic sediments. Velocity analysis and PreSDM data confirm that the apparent inversion zone is caused by an isometric velocity anomaly which in its turn is caused by a gas chimney. Introduction The Yamburg supergiant gas field located in the northern
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Depth Imaging Unfolds Complex Geology and Impacts Reserves - the Q4 Story
Authors M. Kemme, G. Brown, N. van Buuren and M. GreenwoodP071 DEPTH IMAGING UNFOLDS COMPLEX GEOLOGY AND IMPACTS RESERVES – THE Q4 STORY M. KEMME 1 G. BROWN 2 N. VAN BUUREN 3 and M. GREENWOOD 4 Abstract 1 In a very complex structural area two recent successful exploration wells have been drilled. Because of the complex ray paths in the overburden seismic quality of the conventionally processed seismic time data was patchy and there were indications that the lateral positioning of the major structural elements was not always correct. Pre-stack depth migration produced a much clearer seismic data set showing a widening of the structure and a small but
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Application of Prestack Kirchhoff Time Migration to Vertical Cable Seismic Data
More LessP 072 Summary APPLICATION OF PRESTACK KIRCHHOFF MIGRATION TO VERTICAL CABLE SEISMIC DATA H.J. WANG 1 2 and X.-Y. LI 1 1 British Geological Survey West Mains Road Edinburgh EH9 3LA 2 University of Edinburgh Department of Geology and Geophysics The Vertical cable seismic (VCS) represents an alternative method to acquire 3-D seismic data by using vertical arrays of hydrophones instead of conventional horizontal arrays. Based on its unique geometry we develop a prestack Kirchhoff time migration algorithm to perform vertical cable seismic imaging on the common receiver gather. The modified traveltime equation is used in this technique and the
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Beamlet Migration Using Gabor-Daubechies Frame Propagator
More LessP074 BEAMLET MIGRATION USING GABOR-DAUBECHIES FRAME PROPAGATOR Abstract 1 Beamlet migration using Gabor-Daubechies frame propagator with local perturbation theory is developed and tested. The method is formulated with a local background velocity and local perturbations for each window of the wave field decomposition using Gabor-Daubechies frame. The propagators and phase-correction operators are obtained by one-way operator decomposition and screen approximation. The numerical tests on point-spreading responses and the SEG-EAGE salt model poststack data demonstrate the great potential of this approach applied to seismic migration. Keywords: seismic migration wavelet transform beamlets Gabor-Daubechies frame. Introduction Steinberg (1993) Steinberg and Birman (1995) derived
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Antialiasing for n-D Kirchhoff Operators
Authors P. Mazzucchelli and F. Rocca���� ������������������������������ ��������� ��������������� � ���������� � �������� � �������������������������������������������������������������������������������������������������� ������������������������������������������ ���������������������������������������������������� �������������������������������������������������������������������������������������������������� ���������������������������������������������������������������������������������������������� ���� �������������� ����� ��������� �������� ��� ������������ ���� ������������� ������������ ��������� �� ����������������������������������������������������������������������������������������������� ����� ��� ��������� ��� ������������ �������� ������ ���� ��������������� ��� ����� ���� ������������ ������������������������������������������������������������������������������������������� �������������������������������������������������������������� ������������ ������ ����������� �������� ����� ��� ����� ��� ����� ����� ������ ���������� ������ ��� ���������� ������ ��������������������������������������������������������������������������������������������������� ������������������������������������������������������������������������������������������������ �������������������������������������������������������������������������������������������� ������������������������������������������������������������������������������������������������������ ������� ���������� �������������� ������ ����� ���� ���������� ������� �������� �������� ����������� �� ��������������������� ������������������������������������������������������������������������������������������ � � � �������� �������������������������������������������������� ���� �� ������ ������ ����� ������� ���� �� ��� �������� ���������� ����� ���� ��� ���� �� �������� ������� ������
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Common-Reflection-Surface Stack for Common Offset - Practical Aspects
Authors S. Bergler, G. Höcht, Y. Zhang and P. HubralP076 COMMON-REFLECTION-SURFACE STACK FOR COMMON OFFSET: PRACTICAL ASPECTS AUTHOR(S) S. BERGLER G. HÖCHT Y. ZHANG and P. HUBRAL Address Geophysical Institute University of Karlsruhe Hertzstr. 16 76187 Karlsruhe Germany Introduction. In the last years the Common-Reflection-Surface (CRS) stack has been established as a real alternative to standard seismic reflection imaging routines such as the CMP stack or the NMO/DMO/stack. The CRS stack provides a simulated zero-offset (ZO) section from 2-D multi-coverage prestack reflection data without any knowledge about the macro-velocity model (see e.g. Mann et al. 1999; Hubral 1999). In case of a 2-D laterally inhomogeneous medium the CRS stacking
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Common-Reflection-Surface Stack and Conflicting Dips
By J. MannP077 COMMON-REFLECTION-SURFACE STACK AND CONFLICTING DIPS AUTHOR(S) J. MANN Address Geophysical Institute University of Karlsruhe Hertzstr. 16 76187 Karlsruhe Germany Summary. The recently introduced common-reflection-surface (CRS) stack simulates a zero-offset (ZO) section from multi-coverage seismic reflection data for 2-D media in a data-driven way i. e. without explicit knowledge of the macro-velocity model. The “best” stacking operators are determined by an optimization of the coherency along different test stacking operators in the multi-coverage data. Previous implementations determine only one optimum stacking operator for each ZO sample to be simulated. Consequently conflicting dips are not taken into account but only the
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Common-Reflection-Surface Stack for Common Offset - Theoretical Aspects
Authors Y. Zhang, S. Bergler and P. HubralP078 COMMON-REFLECTION-SURFACE STACK FOR COMMON OFFSET – THEORETICAL ASPECTS Y. ZHANG 1 2 S. BERGLER 1 P. HUBRAL 1 1 Introduction. The recently established zero-offset (ZO) Common-Reflection-Surface (CRS) stack has been shown to be an efficient macro model-independent data-driven process to obtain well simulated ZO sections from multi-coverage data. However the ZO CRS stack yields only simulated ZO stack sections for P-P reflections. For the construction of simulated common-offset (CO) sections we modified the ZO CRS stack theory to the CO case. The CO CRS stack can not only be applied to CO P-P reflections S-S reflections but also to
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Imaging-Inversion with Focusing in Dip
Authors S. Brandsberg-Dahl, M.V. De Hoop and B. UrsinP 079: IMAGING-INVERSION WITH FOCUSING IN DIP SVERRE BRANDSBERG-DAHL 1 MAARTEN V. DE HOOP 1 and BJORN URSIN 2 1 Center for Wave Phenomena Colorado School of Mines Golden CO 80401 USA. 2 NTNU Department of petroleum technology and applied geophysics N-7491 Trondheim Norway. Summary If the geology is complex and the rayfield becomes multi-pathed the quality of subsurface images deteriorates. To overcome this problem we perform the imaging in terms of scattering-angle and azimuth at the image point. The images are generated using an algorithm based on the inverse generalized Radon transform. Stacking only over migration dip angles we
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Antialiased 3D True Amplitude Common Diffraction Angle Migration by Regularization in the Dip Domain
Authors V. Rousseau, L. Nicoletis and H. RakotoarisoaP080 ANTIALIASED 3D TRUE AMPLITUDE COMMON DIFFRACTION ANGLE MIGRATION BY REGULARIZATION IN THE DIP DOMAIN Abstract 1 Within the framework of the development of a 3D Kirchhoff pre-stack true amplitude time migration this paper deals with the correction of irregular sampling in the acquisition geometry and the problems due to the migration operator aliasing phenomena. In our approach the sampling of traces in the acquisition domain is translated into a sampling in dip illumination at each image point. The correction of the sampling irregularities is then accomplished by defining weights for the traces in the migration kernel from the triangulation
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Effects of Thin Layers on the Detection of Azimuthal Anisotropy Using P-Waves
Authors Y.J. Liu, A. Ziolkowski, E. Liu and X.-Y. LiP-091 EFFECTS OF THIN LAYERS ON THE DETECTION OF AZIMUTHAL ANISOTROPY USING P-WAVES YI-JIE LIU 1 2 ANTON ZIOLKOWSKI 1 ENRU LIU 2 and XIANG-YANG LI 2 1 Department of Geology and Geophysics The University of Edinburgh West Mains Road Edinburgh EH9 3JW UK 2 British Geological Survey Murchison House West Mains Road Edinburgh EH9 3LA UK Introduction Rocks with aligned vertical fractures give rise to azimuthal anisotropy in seismic data and the recorded P-wave amplitudes show an elliptical variation with azimuth. The direction of the long axis indicates the fracture orientation and the ratio of the long to short
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Seismic Waveform Tomography - the Effect of Layering and Anisotropy
Authors R.G. Pratt, R.E. Plessix and W.A. MulderP092 SEISMIC WAVEFORM TOMOGRAPHY: THE EFFECT OF LAYERING AND ANISOTROPY Summary 1 We describe the waveform tomographic inversion of seismic crosshole data from the Nimr field in Oman. Our initial ray-theoretical inversions of the traveltimes suggest a low level of P-wave anisotropy as do our initial long-wavelength waveform inversion results. Higher resolution 2-D waveform inversions that include this low level of background anisotropy are successful in modelling the observed data but the velocity models are smoother than expected. Surprisingly similar waveform inversions that do not include any anisotropy are also successful in modelling the observed data. These latter inversions yield
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Inversion of P-Wave Data in Laterally Heterogeneous VTI Media - Part I - Plane Diping Interfaces
Authors A. Pech, V. Grechka and I. Tsvankin¡ £ ¥ § © � � � � � © � � � � � ¡ � � � � � � � � © � � � � � � � � � � � � � � � � � � � � � � � � © � � � © � � � © � � � � � � � © © � � © � � � � � � � � � � � � � � � � � � � � � � � � �
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3D Wavefront Construction for P and SV Waves in Transversely Isotropic Media
Authors J. Mispel and P. WilliamsonP094 3-D WAVEFRONT CONSTRUCTION FOR P & SV WAVES IN TRANSVERSELY ISOTROPIC MEDIA Summary 1 The efficient calculation of 3-D Green’s functions in anisotropic elastic media required for asymptotic migration/inversion methods of seismic reflection data is still a challenge. Vinje et al. (1993) and Lambaré et al. (1996) presented the wavefront construction method (WFC) for isotropic media. It allows fast calculation of multi-valued traveltime and amplitude maps which are important for good imaging results in areas with a complex geological structure. We present an extension for the WFC method based on the implementation of Lucio et al. (1996) for 3-D
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Comparison of Averaging Processes for Equivalent Fine Layered Media
Authors G. Bernasconi, M. Beretta, A. Colombo and G. DrufucaP095 COMPARISON OF AVERAGING PROCESSES FOR EQUIVALENT FINE LAYERED MEDIA Abstract 1 Fine layered media can be treated in the long wavelength limit as an equivalent compound medium. The parameters of the replacement medium (compound parameters) can be seen as some kind of weighted average of the parameters of the constituents. Many authors have obtained analytic description of the parameters to be averaged and of the averaging process. In this paper we analyze the properties of the compound medium obtained with different averages over the same ensemble as indicated in Helbig (1994). Equivalent medium of an horizontally fine layered media
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The Effect on Seismic Anisotropy of Fluid Flow in Cracked Media
Authors S.R. Tod, J.A. Hudson and E. LiuP096 THE EFFECT ON SEISMIC ANISOTROPY OF FLUID FLOW IN CRACKED MEDIA Abstract 1 Transfer of fluid between connected cracks may occur during the passage of seismic waves. Such fluid flow can be modelled using an extension of effective medium theory (Hudson et al. 1996) and is effected via non-compliant pores. The flow is governed by a parameter τ representing the relaxation time of pressure equalization between cracks. However if the cracks are fully aligned and have the same aspect ratio the theory produces the unexpected result that at low frequencies the cracks are effectively isolated and at high frequencies
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Effective Models of Media Consisting of Alternating Porous and Elastic Layers
By L. MolotkovP097 EFFECTIVE MODELS OF MEDIA CONSISTING OF ALTERNATING POROUS AND ELASTIC LAYERS L.MOLOTKOV St.Petersburg Branch of Steklov Mathematical Institute Fontanka 27 191011 St.Petersburg Russia 1 Summary. For the medium consisting of alternating porous and elastic layers with slide contact on boundaries the effective model is established. This model is four-phase one and four waves propagate in it. In the case when thickness of elastic layers is very small the effective model is a partial case of the transversely isotropic Biot model. The investigations of wave propagation in porous and fractured media are fulfilled on the basis of the effective models.
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Acoustic Behavior of Fractures under Static Stress
Authors M. Schoenberg and S. Nakagawa��� � � � � �� � � � � � �� � � � � � � � � � � �� � � � � � � � �� � � � � � � � � � � � ��� � � �� �� � � � � � � � � � � � � � � � � � � �� � � � � �� � � � � � � �� �� � � � � � � � � �� � � � � � � � � �� � � �
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Scalar and Vector Models of Constant Q Wave Propagation
By A.J. HanygaP099 SCALAR AND VECTOR MODELS OF CONSTANT Q WAVE PROPAGATION ANDRZEJ HANYGA Institute of Solid Earth Physics University of Bergen All’egaten 41 N5007 Bergen Summary A rigorous scalar model and an approximate isotropic vector model of constant-Q seismic wave propagation are presented. Introduction In many applications of seismic modeling it is necessary to account for attenuation but the specific physical mechanism involved is irrelevant. This is particularly true for seismic wave propagation outside reservoir regions. In this case the constant-Q assumption seems an ideal solution since it requires just one parameter and yet it is consistent with observations over a
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Prestack Depth Migration-Based Poisson's Ratio Determination Using Converted Waves
Authors E.M. Menyoli and D. GajewskiP-105 PRESTACK DEPTH MIGRATION-BASED POISSON’S RATIO DETERMINATION USING CONVERTED WAVES Abstract E. M. MENYOLI and D. GAJEWSKI University of Hamburg Bundesstrasse 55 D-20146 Hamburg Germany The traveltime curves or maps required for migrating converted waves (C-waves) depends on P- and S-wave velocities of the medium where the wave propagates. Consequently incorrect ¡ £ ¦ ¨ ratio (equivalent Poisson’s ratio) leads to incorrect depth images. An indication of errors in the Poisson’s ratio model is residual moveout or depth deviation in the prestack depth migrated PSimage gathers. The Poisson’s ratio estimation method presented here is an iterative optimization method.
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Imaging Improvements Utilizing 3D Multicomponent Seismic Data - a Case History in West Cameron Area, Gulf of Mexico
More LessP106 IMAGING IMPROVEMENTS UTILIZING 3D MULTICOMPONENT SEISMIC DATA – A CASE HISTORY IN WEST CAMERON AREA GULF OF MEXICO S. KNAPP 1 N. PAYNE 1 and T. JOHNS 2 Summary 1 Results from the worlds largest 3D four component OBC seismic survey will be presented. Located in the West Cameron area offshore Gulf of Mexico the survey operation totaled over 1000 square kilometers and covered more than 46 OCS blocks. The area contains numerous gas invaded zones and shallow gas anomalies that disturb the image on conventional 3D seismic which only records compressional data. Converted shear wave data allows images
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Pre-Stack Depth Migration Workflow for Converted Waves
Authors E. Shoshitaishvili, O. Mikhailov and C.W. FrasierP107 PRE-STACK DEPTH MIGRATION WORKFLOW FOR CONVERTED WAVES Summary We present a pre-stack depth migration (PSDM) workflow for converted waves. This flow is equivalent to that for compressional waves with a few modifications. We use synthetic data to demonstrate that this workflow produces PS images that are consistent with PP images. Introduction The advantages of using converted-wave data in exploration and reservoir characterization include imaging through gas clouds (e.g. Valhall field Thomsen et al. 1997) and imaging of sands with low P-wave impedance contrasts (e.g. Alba field MacLeod et al 1999). In addition simultaneous analysis of PP and PS data
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Calculation of Traveltimes for Reflected Converted Waves Using the Common Converting Element Method
More LessP108 CALCULATION OF TRAVELTIMES FOR REFLECTED CONVERTED WAVES USING THE COMMON CONVERTING ELEMENT METHOD D. GARZA-ROCHA U.A.N.L. Facultad de Ciencias de la Tierra A.P. 104 67700 Linares N.L. Mexico ABSTRACT In the present paper are carried out numerical calculations of a new approximation to obtain the traveltime for P-SV re ected converted waves. A set of sources emit P-waves and they travel to a given interface. These waves are converted in S-waves after the re ection and they are recorded at the corresponding receivers as P-SV converted waves. Common converting elements (CCE) have been simulated by fans of rays emmitted
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Converted-Wave Imaging in Inhomogeneous, Anisotropic Media - Part I - Parameter Estimation
More LessP109 CONVERTED-WAVE IMAGING IN INHOMOGENEOUS ANISOTROPIC MEDIA – PART I – PARAMETER ESTIMATION Summary 1 In transversely isotropic media with a vertical symmetry axis (VTI) the converted-wave (Cwave) moveout over middle-to-long offset range is determined by four parameters. These are the C-wave stacking velocity VC2 vertical and effective velocity ratios γ0 and γeff and anisotropic parameter χeff. Detailed numerical analysis is performed to evaluate the sensitivity and error propagation during C-wave moveout inversion. The results show that the two velocity ratios cannot be resolved by semblance analysis with sufficient resolution and accuracy even for exact inputs of VC2 and χeff.
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PP + PS = SS
Authors V. Grechka and I. Tsvankin¡ £ £ £ § § ¨ § © � © © � � � � � � � � � � � � �� � � � � � � �� � � � � � ��� ��� � � � � � � � � � � � � � � � � � � ��� � � � � � � � � � � � � ��� � � � �� ��� � � � � � � � � � � �� � � � � � �� � � � � � �
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PS-Wave Conversion-Point Equations for Layered Anisotropic Media
More Lessc 2 ⎡ ⎢ V ∆t = ⎣ n ∑ i= 1 2 S 2i S 0i 2 ⎤⎡ ⎤ ⎡ ⎥⎢ V ∆t ( 1 + 8η ) ⎥ − ⎢ V ∆t ⎦⎣ ⎦ ⎣ n ∑ i= 1 4 P2i P0i ⎡ 2⎢ V ∆t + V ∆t ⎣ n ∑ i= 1 2 P2i i P0i ∑ i= 1 n n ∑ i= 1 2 P2i 2 S 2i P0i S 0i ⎤ ⎥ ⎦ ⎤⎡ ⎥⎢ V ∆t 1 − 8ζ ⎦⎣ 4 n ∑ i= 1 4 S 2i S 0i ( ) where
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Robust Estimation of Anisotropy Parameters from Correlation of PP and PS Images and Wells
Authors O. Mikhailov and E.F. HerkenhoffP113 ROBUST ESTIMATION OF ANISOTROPY PARAMETERS FROM CORRELATION OF PP AND PS IMAGES AND WELLS O. MIKHAILOV 1 and E. F. HERKENHOFF 2 Summary Isotropic imaging of 4C data at Alba has resulted in significant mismatches between reflector depths in PP and PS images and the depths determined from well control (Mikhailov et al. 2001). These mismatches indicate that the subsurface at Alba is effectively anisotropic. We present a simple procedure for estimating anisotropy parameters of the effective TI medium based on these depth mismatches. Our analysis relies primarily on near-offset information and therefore may be more robust than methods
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Converted-Wave Imaging in Inhomogeneous, Anisotropic Media - Part II - Prestack Migration
More LessP114 CONVERTED-WAVE IMAGING IN INHOMOGENEOUS ANISOTROPIC MEDIA – PART II – PRESTACK MIGRATION Summary 1 We assume a scatter point located beneath a stack of layers with vertical transverse isotropy (VTI) and derive an accurate double-square-root (DSR) C-wave diffraction equation. We demonstrate how this DSR equation can be incorporated into the Kirchhoff prestack time migration. The DSR equation is accurate for long offsets and is controlled by five parameters: P- and S-wave stacking velocities VP2 and VS2 vertical velocity ratio γ0 and anisotropic parameters ηeff and ζeff. These parameters can be inverted from the four C-wave moveout attributes (VC2 γ0
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Evidence for Azimuthal Anisotropy of Near-Surface in Eastern Siberia
Authors W.V. Karsten and S.B. GorshkalevP115 EVIDENCE FOR AZIMUTHAL ANISOTROPY OF NEAR-SURFACE IN EASTERN SIBERIA Abstract 1 Azimuthal anisotropy of the weathering layer was detected using S-waves from 3C VSP and 2x2C surface seismic data at the Urubchen-Tokhomo zone in Eastern Siberia. It shows significant correlation with surface topography. Time delay for the two-way travel time is up to 100ms and thickness of the anisotropic layer is up to 540m. This makes data processing for anisotropy much more complicated especially for surface observations. Introduction Urubchen-Tokhomo hydrocarbon bearing zone is situated in the Eastern Siberia and is considered a possible location for several new giant or
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Detection of Shear-Wave Splitting and Fracture Orientation from PS Waves at the Valhall Field
More LessP116 DETECTION OF SHEAR-WAVE SPLITTING AND FRACTURE ORIENTATION FROM PS WAVES AT THE VALHALL FIELD MIN LOU YAOHUI ZHANG and LONG DON PHAM 1 PGS Research Division 738 Highway 6 South Suite 300 Houston TX 77079 USA Abstract We present a two-component rotation/cross-correlation method to detect shear-wave splitting and fracture orientation from PS converted waves. By analyzing a set of synthetic data and a set of 2D-4C ocean bottom cable (OBC) field data recorded on the Valhall field North Sea our results demonstrate that the two-component rotation/cross-correlation method is robust to detect shear-wave splitting and its implied fracture orientation and
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C-Wave Resolution Enhancement through Birefringence Compensation at the Valhall Field
Authors P.-Y. Granger and J.-M. BonnotP118 C-WAVE RESOLUTION ENHANCEMENT THROUGH BIREFRINGENCE COMPENSATION AT THE VALHALL FIELD. Introduction 1 Most often the first step in 3D C-wave processing is to rotate the multicomponent data into the radial-transverse coordinate system. The radial axis corresponds to the horizontal source-receiver direction and the transverse axis to the perpendicular horizontal direction. In this coordinate system assuming no structure scattering and no azimuthal anisotropy effects all the shear energy should be concentrated on the radial component. The shear wave splitting effect generated by azimuthal anisotropy can result in a significant amount of energy being recorded on the transverse component. If this
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Train Induced Ground Vibrations - the Effect of a Rail Embankment
Authors A. Ditzel and G.C. HermanP-125 Summary TRAIN INDUCED GROUND VIBRATIONS: THE EFFECT OF A RAIL EMBANKMENT A. DITZEL and G. C. HERMAN Centre for Technical Geoscience Department of Applied Mathematics Delft University of Technology P.O. Box 5031 2600 GA Delft The Netherlands Trains can generate vibrations due to irregularities in the track. We have developed a method to determine the ground vibrations from a train moving over a rail embankment which is embedded in a layered ground. Displacements in the free field are obtained by numerical solution of a domain integral equation. We discuss an efficient solution method to solve this integral equation. Introduction
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Flexible VHR Marine 3D Seismic Method for Small-Scale Site Surveys in Shallow Water
Authors T. Missiaen, W. Versteeg, P. Diviacco, B. Marsset and J.-P. HenrietP126 FLEXIBLE VHR MARINE 3D SEISMIC METHOD FOR SMALL-SCALE SITE SURVEYS IN SHALLOW WATER Introduction 1 The adaptation of marine 3D seismic acquisition to very high and ultra high (multi kHz) frequency investigations is advancing slowly. In the early 90s the Renard Centre of Marine Geology (University of Gent) demonstrated that it is feasible to acquire VHR 3D seismic data in a modest and cost-effective way thereby entering the world of small-scale geological structures (Henriet et al. 1992; Marsset et al. 1998). Despite the good results the data were not of the optimum quality due to a number of technical
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3D Preprocessing Techniques for Marine VHR Seismic Data
Authors N. Wardell, P. Diviacco and R. SinceriP127 3D PREPROCESSING TECHNIQUES FOR MARINE VHR SEISMIC DATA Summary Current construction technology and positioning capabilities of 3D marine acquisition systems do not allow small variations in their positioning to be measured with sufficient accuracy for very high resolution marine data. Pre-processing methodologies are having to be developed that are able to correct these problems using only information derived from the seismic data themselves. An automated methodology in 3D is presented which derives corrections for variations due to tides and wave motion directly from the seismic data. Application of these corrections produces improved results in the stacked seismic 3D volumes.
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Blasting Vibration Monitoring from Coal Mine on Memshi Village
Authors M.A. Riaha and J. ShahabianP128 BLASTING VIBRATION MONITORING FROM COAL MINE ON MEMSHI VILLAGE 1 M.ALI RIAHI and JAFAR SHAHABIAN Institute of Geophysics Tehran University PO Box 14155-6466 Tehran Iran Abstract An attempt was made to study the effect of seismic vibration produced from Tarik Darreh coal mine blast at the Memshi village area. The recording devices were PDAS-100 the natural frequency of the L-4C three component seismometers was 1 Hz and the distances between the devices were from 100 to 650 meters. The data were recorded along a radial and radial - tangential profiles. The recording length was two minutes with a sampling
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Complex Processing of Refracted and Reflected Waves of Caspian Shallow Water Zone Data Set
Authors Y.V. Roslov, A.N. Telegin, T.S. Sakoulina, I.M. Tikhonova and S.A. NechkhaevP129 COMPLEX PROCESSING OF REFRACTED AND REFLECTED WAVES OF CASPIAN SHALLOW WATER ZONE DATA SET INTRODUCTION 1 For two last years State Company “Sevmorgeo” in cooperation with State Company ”Yuzhmorgeologia” took part in the seismic investigations of Russian very shallow water zone (0.5-2 meter depth) of Caspian Sea by means of radiotelemetric registration system “BOX”. The seismic design included very long for such kind of project receiver lines that allowed acquiring data with offsets up to 12480 meters and tracing refracted as well as refracted waves originated at the same geological interfaces. The example of the field record is shown
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A High-Resolution 2D/3D Seismic Study of a Thrust Fault Zone in Lake Geneva, Switzerland
Authors M. Scheidhauer, M. Beres, D. Dupuy and F. MarillierP130 A HIGH-RESOLUTION 2D/3D SEISMIC STUDY OF A THRUST FAULT ZONE IN LAKE GENEVA SWITZERLAND M. SCHEIDHAUER M. BERES D. DUPUY and F. MARILLIER 1 Institute of Geophysics University of Lausanne 1015 Lausanne Switzerland Summary A high-resolution three-dimensional (3D) seismic reflection survey has been conducted in Lake Geneva near the city of Lausanne Switzerland where the faulted molasse basement (Tertiary sandstones) is overlain by complex Quaternary sedimentary structures. Using a single 48-channel streamer an area of 1200 m x 600 m was surveyed in 10 days. With a 5-m shot spacing and a receiver spacing of 2.5 m in the
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A Very Shallow (0-100m) 3D Land Seismic Survey near Boulogne-sur-Mer, N-France
Authors G.G. Drijkoningen, D. Draganov, H. Van der Meer, A. Volker and A.K.T. WeverP131 A VERY SHALLOW (0 – 100 M) 3-D LAND SEISMIC SURVEY NEAR BOULOGNE-SUR-MER (N-FRANCE) Introduction 1 In September 2000 a very shallow 3-D seismic survey was performed on a beach just north of Boulogne-sur-Mer in Northern France. This survey has multiple objectives. One objective is to see whether predicted amplitudes from a tailor-made design could be seen in the final 3-D image (acquisition foot print). Another objective is to obtain a structural image of the upper 100 m of the subsurface so it could be verified against a very nearby geological outcrop. The last objective is to come to
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Seismoacoustic Investigations of Buried Karst in the Dam Foundations in the Daugava Basin
By V. LisinP132 SEISMOACOUSTIC INVESTIGATIONS OF BURIED KARST IN THE DAM FOUNDATIONS IN THE DAUGAVA BASIN V. LISVIN High resolution seismoacoustic and shallow seismic methods and the equipment are discussed for investigations of buried karst and increased water infiltration zones in the dam foundations in the Latvian part of the Daugava basin. Multiwave approach to the shallow CDP seismics and VSP data interpretation together with subbottom seismoacoustic profiling provide information for planning of the repair and maintenance work on the dams. 1 Interseis Energetiku Str. 1-9 2121 Salaspils Latvia Introduction After the filling of reservoirs of the hydroelectric power station cascade on
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Seismic-Electric Benchmarking of Shallow Subsurface Horizons and Dome Cavities
Authors T.V. Sorokina and A.A. BoulytchovP133 SEISMIC-ELECTRIC BENCHMARKING OF SHALLOW SUBSURFACE HORIZONS AND DOME CAVITIES TATIANA V. SOROKINA and ANATOLI A. BOULYTCHOV Russian Academy of Science Siberian Branch Institute of Geophysics 3 Prospect Koptyug 630090 Novosibirsk Russia Abstract 1 Seismic-electric (SE) effect method was applied in field to foresee subsurface dome cave emptinesses and to benchmark underground water horizons. A source of seismic waves were blows of a heavy hammer or repeated powerful impulses of magnetostrictive installation. Main frequency used was 500 Hz. Passing layers the seismic wave caused electromagnetic fields on the boundary interfaces. Electric responses of these electromagnetic fields were measured on a
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Examination of the Marathon Dam by the Use of Geophysical Methods
Authors V.K. Karastathis, P.N. Karmis, G.K. Drakatos and G.N. StavrakakisP134 EXAMINATION OF THE MARATHON DAM BY THE USE OF GEOPHYSICAL METHODS Summary 1 Geophysical investigations were conducted at the site of the Marathon Dam. The project was aiming to test the Dam after the Athens earthquake of 7/9/1999. Implemented methods included geoelectrical seismic and GPR techniques. The results indicated the existence of areas with high conductivity which can be associated with possible leakage and others with low seismic velocity which can be associated with unconsolidated material. Introduction V. K. KARASTATHIS 1 P. N. KARMIS 2 G. DRAKATOS 1 and G. STAVRAKAKIS 1 1 National Observatory of Athens Geodynamics Institute
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The Subsurface Revealed - the "Seismic Microscope
Authors T. Tóth, R. Vida, P. Szafián, N. Fekete and F. HorváthP135 THE SUBSURFACE REVEALED – THE “SEISMIC MICROSCOPE” Abstract 1 High- and ultra-high resolution water-born seismic techniques have been successfully applied to engineering and environmental problems. Key to the success is the unparalleled resolution one can achieve on water with advanced seismic profiling systems. This paper first demonstrates the resolving power comparing high- and ultra-high resolution seismic profiles measured above the same location. This is followed by case studies focusing on some specific problems successfully solved by the technique. Case studies include seismic surveys carried out on river Danube next to the Hungarian Nuclear Power Plant (TÓTH & HORVÁTH 1999)
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3D GPR Data Acquisition and the Influence of Positioning Errors on Image Quality
Authors J. Groenenboom, J. Van der Kruk and J.H. ZeemanP141 3D GPR DATA ACQUISITION AND THE INFLUENCE OF POSITIONING ERRORS ON IMAGE QUALITY Summary J. GROENENBOOM J. VAN DER KRUK and J.H. ZEEMAN Delft University of Technology Applied Earth Sciences Mijnbouwstraat 120 2628 RX Delft The Netherlands Two 3D GPR data sets have been acquired over the same test site. The first data set was recorded manually. Positioning errors caused discontinuous behaviour of the measurements along the crossline direction. After application of a migration algorithm we observe that the image quality is distorted. The second data set was acquired with an automated measurement frame with high positioning accuracy. The
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Elastic/Electromagnetic Wave Propagation - Equivalences and 2D Modelling of GPR
Authors R. Laurain and I. LecomteP142 ELASTIC / ELECTROMAGNETIC WAVE PROPAGATION – EQUIVALENCES AND 2D MODELLING OF GPR R. LAURAIN and I. LECOMTE Abstract 1 Electromagnetic waves are often referred to as equivalent to acoustic waves or for reasons of identical polarizations perpendicular to the incidence plane as shear waves. We studied the propagation equation and the reflection/transmission coefficients for both seismics and electromagnetism in order to draw a more precise equivalence. It shows that in 2D the Transverse Electric (TE) mode can be directly modeled as an acoustic wave. For the Transverse Magnetic (TM) mode there is no direct equivalence with seismic since the
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New Lines of Approach to the Problem of Plastic Mines Detection by GPR Method
Authors N. Efimova, G. Pochanin, P. Kholod and V. GlazounovP143 NEW LINES OF APPROACH TO THE PROBLEM OF PLASTIC MINES DETECTION BY GPR METHOD 1 Summary. The method of increasing the plastic landmines electromagnetic properties contrast is offered for the solution of the problem of humanitarian demining. The method is based on artificial change (increase) of electromagnetic wave reflectance from plastic landmines being in soil using the effect of instability of soil geoelectrical characteristics in the aeration zone. The theoretical substantiation of the offered method has been adduced. The outcomes are confirmed both by results of computer simulation and by results of GPR prospecting. Introduction. Development and application of
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Modeling of GPR Reflections and Water Content Estimation of Moist Soils
Authors M. Bano and J.-F. GirardP-144 Introduction MAKSIM BANO and JEAN-FRANÇOIS GIRARD Laboratoire Proche Surface EOST ULP (UMR -7516) 5 rue René Descartes 67084 Strasbourg France Recent studies have shown that Ground-penetrating radar (GPR) is an efficient geophysical method to image the internal structures of aeolian dunes (Bristow et al. 1996; Bano et al. 1999). In these studies changes in water content are believed to cause the radar reflections observed inside the present-day dunes. Greaves et al. (1996) have shown that radar interval velocity (calculated from the normal moveout of the multi-offset GPR data) can be used to estimate water content when the subsurface is
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Interpretation of TEM Small-Loop Data
Authors I.O. Isaev, M.I. Epov, E.Y. Antonov and A.E. PlotnikovP145 INTERPRETATION OF TEM SMALL-LOOP DATA I.O.ISAEV M.I. EPOVI. E.Y. ANTONOV and A.E. PLOTNIKOV Laboratory of Electromagnetic Fields Institute for Geophysics Prospect Akademika Koptuga b.3 630090 Novosibirsk Russia Summary 1 The paper presents advances in the interpretation of the Arbitrary Impulse Method (AIM) data. The AIM is the well-known TEM method. The main features of the AIM are small size of sounding loops and the fully controlled current pulse using. Our key achievement is the quantitative interpretation of the AIM data that is in agreement with the results of VES investigation. Introduction The AIM was formed as the near-surface modification
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The New Approach to Electromagnetic Fields Interpretation for TEM with Areal Observation System
Authors G.M. Trigubovich, M.E. Royak, Y.G. Soloveichik and A.V. ChernyshevP146 THE NEW APPROACH TO ELECTROMAGNETIC FIELDS INTERPRETATION FOR TEM WITH AREAL OBSERVATION SYSTEM Abstract 0 ( ) 1 In carrying out transient electromagnetic studies a coaxial configuration of transmitter and receiver loops moving over some area or along separate profiles are most frequently used. However the know-how with a fixed transmitter loop and moved receiver loops is much more economic and has no less resolution. Difficulties associated with interpretation of measured electromagnetic fields prevent broader introduction of such know-how. Attempts to use transformations as apparent resistivities for configurations with a fixed source do not most commonly allow one to
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On 3D Electromagnetic Inverse Problems in the Case of Arbitrary Relief
Authors P.S. Martyshko and A.L. RoublevP147 ON 3D ELECTROMAGNETIC INVERSE PROBLEMS IN THE CASE OF ARBITRARY RELIEF P.S. MARTYSHKO and A.L. RUBLEV Institute of Geophysics Amundsen Str. 100 620016 Ekaterinburg Russia Introduction 1 Inversion of electromagnetic (EM) data in geophysical prospecting involves solution of a nonlinear-operator equation of the first kind (with an implicit ill-conditioned operator). The numerical solution of such equations requires considerable expenditures of computer time. For the theoretical inverse problem (TIP) the author was able to obtain explicit equations for the electrical and magnetic fields to develop effective algorithms for solving these equations and construct examples of equivalent regions. A TIP is
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Strobe-M - Multi-Function System for Impulse Electric Prospecting
Authors V.A. Tarasov, L.I. Bytensky, V.Y. Chernysh and S.N. ShereshevskyP148 STROBE-M – MULTI-FUNCTION SYSTEM FOR IMPULSE ELECTRIC PROSPECTING Abstract 1 V.A.TARASOV L.I.BYTENSKY V.YU.CHERNYSH and S.N.SHERESHEVSKY VIRG-Rudgeofizika Laboratory of Impulse Electric Prospecting Fayansovaya st. 20 193019 St-Petersburg Russia VIRG-Rudgeofizika developed multi-functional system for impulse electro prospecting STROBE-M. System consists of instrumentation (transmitter receiver borehole probe) field procedures and software (for real-time signal processing and for interpretation). STROBE-M can be used for time domain electro-magnetics (TDEM) time domain induced polarization (TDIP) direct current resistivity and spontaneous polarization (SP) techniques. The system may be employed for ore exploration groundwater exploration and environmental studies structural geology investigation. The STROBE-M receiver (Fig. 1) is
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3D Acquisition-Preserving Fourier DMO in the Log-Stretch Domain
More LessP155 3D ACQUISITION-PRESERVING FOURIER DMO IN THE LOG-STRETCH DOMAIN ANDREY V. MASJUKOV Joint Stock Open Society «Oil-Gas Company «Slavneft» Geophysical R&D Office PO Box 24074 170024 Tver Russia 1 Summary. A 3D F-K DMO method is proposed for the transformation of an elementary crossgather (i. e. 1-fold cube) which shotpoints and receivers are located at two crossing straight lines. If shots and receivers of a cross are regularly sampled along their lines and each receiver records any shot then the method does not encounter offset and azimuth distributions. The main idea is very simple: a true 3D DMO must employ
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Statics and Near-Field Scattering
Authors X.H. Campman, C.D. Riyanti and G.C. HermanP-156 STATICS AND NEAR-FIELD SCATTERING Summary XANDER H. CAMPMAN CH. DWI RIYANTI and GÉRARD C. HERMAN Delft University of Technology Subfaculty of Applied Mathematics Mekelweg 4 2628 CD Delft In seismic data waves scattered at the near surface are a source of deterministic noise. When the scattering occurs near the source or receivers the effect resembles the effect of short-wavelength statics. We present a model study of the near-receiver scattering and find that the effect of such scattering is a complex process involving interfering surface waves. The conventional statics assumption does not hold here. In an attempt to improve processing
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High-Resolution Reflection Seismics at the Bavarian Part of the TRANSALP Profile
Authors R. Thomas, K. Bram, J. Fertig and K. SchwerdP157 HIGH-RESOLUTION REFLECTION SEISMICS AT THE BAVARIAN PART OF THE TRANSALP PROFILE R. THOMAS 1 K. BRAM 1 J. FERTIG 2 and K. SCHWERD 3 Introduction 1 The east-alpine reflection seismic traverse (TRANSALP) is a multi-disciplinary and international research program for investigating orogenic processes by continent-continent collisions focusing on the Eastern Alps. It consists of several seismic and seismological subprojects within a 340 km long and 40 km wide North-South Transect (approx. between Munich and Venice) and is accompanied by complementary geophysical geological and petrological research projects of Italian Austrian Swiss Dutch and German teams (Gebrande 2000). In its northern
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Attenuation of Source-Generated Noise in 3D Cross-Spread Data
Authors B. Heincke, E. Duveneck, B. Milkereit and T. BohlenP 158 Summary ATTENUATION OF SOURCE-GENERATED NOISE IN 3D CROSS-SPREAD DATA B. HEINCKE E. DUVENECK B. MILKEREIT and T. BOHLEN Institute of Geosciences Geophysics Kiel University Otto-Hahn-Platz 1 24118 Kiel Germany In cross-spread geometry source-generated noise( such as ground roll or refracted waves) generally shows rotational symmetry in respect to the center of the data cube. In order to make use of this symmetry to attenuate that noise a transform to polar coordinates followed by a 3D Fourier transform is applied. In the Fourier domain noise with rotational symmetry can be easily identified and removed. This filtering approach was applied
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Coherent Noise Attenuation Using Inverse Theory and Prediction Error Filters
By A. GuittonP 159 COHERENT NOISE ATTENUATION USING INVERSE PROBLEMS AND PREDICTION ERROR FILTERS 1 SUMMARY ANTOINE GUITTON Department of Geophysics Stanford University Stanford CA 94305 USA Two iterative methods that remove coherent noise during the inversion of 2-D prestack data are tested. One method approximates the inverse covariance matrices with prediction error filters (PEFs) and the other introduces a coherent noise modeling operator in the objective function. This noise modelling operator is a PEF that has to be estimated either before the inversion from a noise model or directly from the data. These two methods lead to independent identically distributed (IID)
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Land Multiple Elimination Applicable for Low-Relief Structures
Authors M.S. Bannagi, P.G. Kelamis and D.J. VerschuurP160 LAND MULTIPLE ELIMINATION APPLICABLE FOR LOW-RELIEF STRUCTURES Summary 1 Estimation of multiple energy and subsequent elimination is probably one of the most important aspects of modern seismic data processing. In particular in areas with little or no velocity discrimination between primaries and multiples conventional approaches fail and sophisticated techniques based on wave theoretical principles are usually sought. These techniques have been successfully applied in marine datasets for both surface-related and internal multiples. For land data however the application of wave equation based algorithms for multiple attenuation is rather limited. In this paper we employ the iterative multiple removal method
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Unsupervised Seismic Wave Separation in the Time/Scale Plane
Authors A. Roueff, J. Chanussot, B. Nicolas and J. MarsP161 UNSUPERVISED SEISMIC WAVE SEPARATION IN THE TIME/SCALE PLANE Abstract This paper illustrates a methodology based on an image processing technique to remove and separate surface waves. These waves convey any useful information despite the shot and receivers sensors patterns used during the data acquisition. The elimination of such waves is always desirable to focus on underlying reflection data. Methods based on time frequency and time scale methods are now used to separate surfaces waves. But they are not so convenient because they are not automatic. The proposed method based on the watershed algorithm is an unsupervised and non parametric
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Removing Love Waves and Their Scattering in the Shallow Subsurface
Authors L.F. Van Zanen, G.G. Drijkoningen, J. Brouwer, C.P.A. Wapenaar and J.T. FokkemaP 162 REMOVING LOVE WAVES AND THEIR SCATTERING IN THE SHALLOW SUBSURFACE L.F. VAN ZANEN 1 G.G. DRIJKONINGEN 1 J.BROUWER 2 C.P.A. WAPENAAR 1 and J.T. FOKKEMA 1 1 Section of Applied Geophysics and Petrophysics Department of Applied Earth Sciences Delft University of Technology Mijnbouwstraat 120 2628 RX Delft The Netherlands 2 OYO Centre of Applied Geosciences B.V. Archimedesbaan 16 3439 ME Nieuwegein The Netherlands Introduction SH-waves (Shear Horizontal) are often assumed to be decoupled from the other wave types (P- (Pressure) and SV- (Shear Vertical) waves) in elastic media. In air or gas filled media P-waves are often severely
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An Imaging Approach to Complex Near Surface Effects
Authors C.O.H. Hindriks and D.J. VerschuurP-163 AN IMAGING APPROACH TO COMPLEX NEAR SURFACE EFFECTS C.O.H. HINDRIKS* and D.J. VERSCHUUR Delft University of Technology P.O.Box 5046 2600 GA Delft The Netherlands. [email protected] Summary Effects originating from a complex near surface model can severely degrade the quality of seismic data. Conventionally these effects are handled by assumptions on the model such as assuming vertical raypaths through the near surface. In this paper the effects are handled as a true imaging problem. Kinematic operators which will be used for redatuming are derived from the data. Through an adjusted tomographic inversion additional knowledge on the datum and near surface
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Applications of the 3D Common Focal Point Matrix in Pre-Stack Data Analysis for Migration Aperture and Acquisition Design
Authors J.F.B. Bolte and D.J. Verschuur¡ £ ¥ APPLICATIONS OF THE 3D COMMON FOCAL POINT MATRIX IN PRE-STACK DATA ANALYSIS FOR MIGRATION APERTURE AND ACQUISITION DESIGN JOHN F.B. BOLTE§ 1 and D.J. VERSCHUUR 2 1 Delft University of technology P.O. Box 5046 2600 GA Delft The Netherlands. [email protected] 2 Delft University of technology. Summary We introduce the CFP matrix that is constructed from the data-driven determined traveltime operators using the Common Focal Point technology. This matrix contains all the confocal reflectivity information connected to one point in the subsurface. From the matrix the area in (X Y) that contributes to the image the Zone
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Surface-Wave Propagation in Two-Dimensional Velocity Models and Its Dispersion Curves
Authors K. Hayashi and H. SuzukiP165 SURFACE-WAVE PROPAGATION IN TWO- DIMENSIONAL VELOCITY MODELS AND ITS DISPERSION CURVES 1 Abstract We have studied surface wave propagation in two-dimensional velocity models and its dispersion curves. Several numerical modeling of surface waves were performed in order to study surface wave propagation characters in two-dimensional velocity models. Synthetic waveforms were calculated by a twodimensional finite-difference method. Dispersion curves for synthetic data were obtained through the cross correlation method and the multi-channel analysis of surface waves. A non-linear least square inversion was applied to dispersion curves in order to obtain S-wave velocity models. The results indicate that the surface waves
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Adaptive Multiple Subtraction with Non-Stationary Helical Shaping Filters
Authors J.E. Rickett, A. Guitton and D. GratwickP 167 ADAPTIVE MULTIPLE SUBTRACTION WITH NON-STATIONARY HELICAL SHAPING FILTERS 1 SUMMARY JAMES RICKETT ANTOINE GUITTON AND DOUGLAS GRATWICK Department of Geophysics Stanford University Stanford CA 94305 USA We suppress surface-related multiples with a smart adaptive least-squares subtraction scheme in the time-space domain after modelling multiples with a very fast but approximate modelling algorithm. The subtraction scheme is based on using a linear solver to estimate a damped non-stationary shaping filter. Convergence is improved by the preconditioning with a space domain helical roughening filter. Dragoset and Jeričević (1998) describe a two-step multiple elimination process: prediction followed by subtraction with an
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Wavefield Extrapolation Based on the Local Slant Stacking
Authors M. Denisov and D. FinikovP168 WAVEFIELD EXTRAPOLATION BASED ON THE LOCAL SLANT STACKING MICHAEL DENISOV and DMITRI FINIKOV 1 Geotechsystems Ordzhonikidze 13/2 117071 Moscow Russia Introduction A procedure for transforming data from the original source/receiver depth level to a different one is usually called wavefield extrapolation. The most important applications of this technique are simulation of multiples and peg-legs for their subsequent subtraction and pre- or post-stack datuming. A typical approach to the design of the wavefield extrapolator is the use of the wave equation that results in a Kirchhoff summation operator that maps the surface data into a multiple model or in other
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Least-Square Multichannel Deconvolution
Authors P. Mazzucchelli and U. Spagnolini����� ������������������������� ������������� ������������������������������ ����������������������������������������������������������������� ��������������������������� ������������� �������� � ��������������������������� ������������������������������������������ ������������� ������������ �������������������������������������������������������������������������������������������� ��������������������������������������������������������������������������������������������� ����������� ���� ������ ��������������� ��� �������� ���� ������������� ��� ��������� ��� �������� �� ������������������������������������������������������������������������������������������������ ���������� �������� ����� ������� ������ ���������������� ����� ����������� ������������� ������ �� ������������������������������������������������������������������������������������������� ������������ �������� �������������� ������� ���� �������� ��� ���� ������� ���������� �������������������������� ������������������������������������������������������������������������������������������������������ ������������������������������������������������������������������������������������������������� �������������������������������������������������������������������������������������������� ��� ���� ���� � ���� �� ���� � ���������������������������������������������������������������������������������������������� ������������������������������������������������������������������������������������������������ ������������������������������������������������������������������������������������������������� ����������������������������������������������������������������������������������������������� ��� ���� ������� ���������� ���� ������ ������������� ������� ���� ��������� ���������� ���� ����������� ��� ��� ��������������������������������������������������������������������������������������������������� ������������������������������������������������������������������������������������������ ��������������������������������������������������������������������������������������������� ��������� ��� ���� ������ ��������� ��� ����� �������� ���� ��������� ������������ ��� ���� ��������� ��������������������������������������
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Multiple Removal in the Norwegian Sea - a Comparison of Methods
Authors D.G. King, T. Høy, R. van Borselen and J. BrittanP170 MULTIPLE REMOVAL IN THE NORWEGIAN SEA – A COMPARISON OF METHODS. Summary 1 Removal of free-surface multiples from seismic reflection data is an essential pre-processing step before seismic imaging in many marine environments. Different multiple removal methods were applied to a data set typical of the Norwegian Sea. Comparison of the results indicated that Surface Related Multiple Elimination (SRME) in combination with a differential move-out method gave the best final data. Overview of methods Slowly decaying water layer multiples arising from a strong impedance contrast at the sea floor severely degrade the quality of the seismogram. In addition peg
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Efficient S-Wave Generation in the Presence of Near-Surface Layers
Authors Y. Gourvil, K. Roy-Chowdhury and J. MondtP175 EFFICIENT S-WAVE GENERATION IN THE PRESENCE OF NEAR-SURFACE LAYERS Summary 1 Finite-difference simulations were performed to investigate the generation of shear waves using a buried exploding source. Effects that were studied included depth of the source below the freesurface and the near-surface layering. Conversion at the free-surface appears to be quite efficient and is stronger than the conversion at the deep reflector. The former (pSS) needs simpler processing and may thus be an attractive alternative to the latter (PS) for exploration. Introduction YANN GOURVIL KABIR ROY-CHOWDHURY and JAAP MONDT Applied Geophysics Group Utrecht University Budapestlaan 4 3584 CO Utrecht
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Multicomponent Data Analysis and Wave Separation in Marine Seismic Survey
More LessP176 MULTICOMPONENT DATA ANALYSIS AND WAVE SEPARATION IN MARINE SEISMIC SURVEY X. DAGANY 1 2 J. MARS 1 and F. LUC 2 Abstract 1 1 Laboratoire des Images et des signaux BP 46 38402 Saint Martin d’Hères France 2 Thomson Marconi Sonar This paper presents a theoretical description of signals received by OBS components. After focusing on the principle of the wave propagation through a fluid-sediment interface we will give analytical expressions of the components recorded by the sensors. Firstly we focus on the downgoing waves propagating into the water column; direct and multiple waves. We use this results to
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Ground-Roll Separation Using a Shift Invariance Method for Polarized Wavefields
Authors J. Picheral, M. Becquey, J. Oksman and U. Spagnolini3 *URXQG UROO VHSDUDWLRQ XVLQJ D VKLIW LQYDULDQ�H PHWKRG IRU SRODUL]HG ZDYHILHOGV ������� �� ����������� ���� ������������� ��� ����� ���������� �� ��������������������� ��� �������� ���������� ��������� �� � ������ ����� ��� �� ���������� �� ���������� ��� ���������������� ���������� �� ��� ���� �� ��� ��������� ������� ��� ������ �������� ���� ���� �� �������� ��� ��������������������� �� ������� ���� ��� �� ������ �� �� ������������ ��� ������ �� ����� �� ����� ��������� ������ �� ��� ��������������������� ��� ��� ��� ���������� ��� ������� ��������� �� ���������� ��� ���������������� �������� ��� �� ������� ������ ����� ������ ��� �������� ��� ������������ ��� ������������� �������� ���
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Effect of Velocity Transition Zones on the Apparent Polarization of Ocean-Bottom Cable Data
Authors M. Al-Otaibi, K. Marfurt, F. Hilterman, H. Zhou and N. KabirP178 EFFECT OF VELOCITY TRANSITION ZONES ON THE APPARENT POLARIZATION OF OCEAN- BOTTOM CABLE DATA Summary Velocity transitional zones in shallow marine sediments impact the processing and interpretation of ocean-bottom cable multicomponent data (OBC). These sediments act as a polarization filter that reduces the amplitude of converted waves on the vertical component of OBC data. Based on the models considered in this work such influence is essentially independent of frequency in the seismic band. These observations are reached by modeling realistic earth parameters and applying a total elastic algorithm that includes all wave modes. Introduction Over the last decade ocean-bottom
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The Effect of Geophone Specifications on Vector Fidelity
Authors C.A.M. Faber and H.A. LarooP179 The Effect Of Geophone Specifications On Vector Fidelity Summary 1 A theoretical model was developed to quantify the intrinsic vector fidelity of a geophone. Results from the model were compared with actual test data which was acquired on a low distortion shake-table. A special test fixture was designed containing 30 conventional geophones: 24 geophones positioned horizontally at 30 degree azimuthal increments and 6 geophones oriented vertically. This Multi Azimuth Test Jig (MATJ) was then positioned on a horizontal low distortion shaketable in various rotated and tilted positions. The response of all of the geophones to a swept sine wave
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Decomposition of Multicomponent Ocean-Bottom Data - Experiences in Application
More Less¤ where � � � � � � � � � � and are the density and vertical slowness in the and� water-layer is the horizon- � tal rayparameter. � � � � To resolve the criterion that there should be no primary reflections present in the decomposed downgoing wavefield above (© � the bottom ) is applied. Stage 3. Elastic into� � ¦ ¦ decomposition just below the bottom The next stage is an elastic decomposition below the bottom into up- and downgoing normal stressfields: where ¤ � and � ¡ �� � � � � �
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Correlation Analysis of Dual Sensor Data
Authors R.E. White and M.J. HarrisonP181 CORRELATION ANALYSIS OF DUAL SENSOR DATA ROY E. WHITE and MARK J. HARRISON Summary 1 The scaling factors required prior to summation of seabed hydrophone-geophone traces can be obtained directly from correlation analysis of the data. The analysis can reveal time and phase shifts between the hydrophones and geophones and can be used to estimate the seabed reflection coefficient. Introduction The summation of appropriately scaled normal incidence pressure and velocity fields at the seabed attenuates both water-trapped multiples and receiver-side peg-leg water-layer multiples. Barr and Sanders (1989) demonstrated the practicability of this approach in the field using a seabed
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Detecting and Processing AVO Polarity Reversals
Authors T. Pokrovskaia, F. Adler and P. HarrisP185 DETECTING AND PROCESSING AVO POLARITY REVERSALS T. POKROVSKAIA F. ADLER and P. HARRIS Summary 1 The detection of subtle class I and II AVO features (Rutherford and Williams 1989) rather than classical bright spots is becoming increasingly important in hydrocarbon exploration. However seismic data with AVO effects such as polarity reversals can be difficult to process and analyse. We present a methodology for robust class I and II AVO processing which includes two interlinked components. Firstly we show a new method of velocity analysis which detects residual moveout errors caused by polarity changes versus offset and provides accurate velocities
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AVO Interpretation Improved by Warping Techniques
Authors F. Pivot and Y. El OuairP186 AVO INTERPRETATION IMPROVED BY WARPING TECHNIQUES YOUNESS EL OUAIR and FREDERIK PIVOT 1 TotalFinaElf CSTJF Av. Larribau 64018 Pau Cedex France Abstract It has been proven in the past that attributes computed in the offset or angle domain (so called AVO attributes) can be interpreted as Direct Hydrocarbon Indicators (DHIs). However one main difficulty for the success of such methods is to guarantee that reflection events on common reflection gathers are perfectly flat in the offset or angle direction. However many phenomena can lead to non perfect alignment of reflection events on gathers: small velocity errors anisotropy lateral velocity
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Statistically Uncorrelated AVO Attributes
Authors P. Herrmann and G. CamboisP187 STATISTICALLY UNCORRELATED AVO ATTRIBUTES PHILIPPE HERRMANN and GUILLAUME CAMBOIS Abstract 1 AVO analysis rely on characteristic AVO attributes derived from the amplitude behavior of the back scattered seismic wave field recorded over a range of offsets (or angles AVA). An early settled practice consists in the production of two stacks: a near offset stack (with the first half range of offsets) and a far offset stack (with the second half range of offsets). The two above mentioned AVO attributes fulfill two important requirements: (1) High signal to noise ratio: compared to the individually recorded traces the S/N ratio is
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Gardner's Relations and AVO Inversion
Authors A.-S. Barnola and R.E. WhiteP188 GARDNER'S RELATIONS AND AVO INVERSION Summary 1 AVO inversion is frequently stabilised by constraining changes in velocity and density to obey a Gardner type relation. The penalty for this constraint is that the estimates from inversion become biased. While a single Gardner relation may describe the correlation between variations in velocity and density within a particular rock type it is generally not appropriate to changes from one rock type to another nor is it appropriate to changes in fluid content within a specific rock type. As changes in fluid content are of prime interest in AVO inversion it is
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Testing of Different Modifications of Multiwave AVO-Analysis by Model Data
Authors V.V. Bouzloukov and T.V. NefedkinaP189 TESTING OF DIFFERENT MODIFICATIONS OF MULTIWAVE AVO-ANALYSIS BY MODEL DATA TATIANA V. NEFEDKINA and VADIM V. BOUZLOUKOV Summary 1 The paper presents results of comparative analysis of different wave combinations (PP+PS) (PP+SH) (PP+SV) as applied to inversion of AVO-response. Our approach is based on the combined inversion of a polynomial approximation for dependencies between reflection coefficients of compressional shear and converted waves and incidence angles. Linearized problem has been considered. Accuracy and stability of inverse problem solution have been studied using numerical experiments for two-layered model. An iteration R-algorithm allowing to obtain stable non-biased estimators of elastic parameters of
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New Formulation for Reflection Coefficients
By F. BorocinP 190 Summary NEW FORMULATION FOR REFLECTION COEFFICIENTS F. BOROCIN 1 2 1 British Geological Survey West Mains Road Edinburgh EH9 3LA 2 University of Edinburgh Department of Geology and Geophysics We offer a new formulation for reflection-transmission coefficients. It has the advantage of keeping a matrix-bloc structure useful for computation. Yet each individual coefficient can easily be visualised. We present the derivation of the formula and give some of its consequences and applications. Introduction The reflection-transmission coefficients for elastic SH-waves at the interface between two elastic isotropic media can be written as the solution of a 2*2 matrix system
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A New Approximation of the Reflection and Transmission Coefficients between Two Visco-Elastic Isotropic Media
More LessP192 A NEW APPROXIMATION OF THE REFLECTION AND TRANSMISSION COEFFICIENTS BETWEEN TWO VISCO-ELASTIC ISOTROPIC MEDIA ALEXEY STOVAS and BJØRN URSIN NTNU Dept. of Petroleum Engineering and Applied Geophysics 7491 Trondheim Norway 1 INTRODUCTION We consider the plane-wave reflection and transmission (R/T) coefficients between two isotropic viscoelastic media where the medium parameters are complex function of frequency (Ben-Menahem and Singh 1981). Continuity of stress and displacement velocity gives the exact equations for the R/T coefficients (Aki and Richards 1980). By normalizing the R/T coefficients with respect to vertical energy-flux and using the formulation in Ursin and Stovas (2000) the equations for
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Petrophysical Inversion of Well-Log and VSP Data Using a Dual-Porosity Model
Authors J. Yan, E Liu, X-Y. Li and R. ScruttonP- 195 PETROPHYSICAL INVERSION OF WELL-LOG AND VSP DATA USING A DUAL-POROSITY MODEL Introduction Yan Jun 1� 2 Enru Liu 1 Xiang-Yang Li 1 and Roger Scrutton 2 1 British Geological Survey Murchison House West Mains Road Edinburgh EH9 3LA UK 2 Department of Geology and Geophysics University of Edinburgh UK To link seismic velocity with reservoir parameters the time-average equation of Wyllie et al. (1956) is widely used. The time-average equation assumes that the travel time of seismic wave is linearly dependent on pore uid solid frame and their relative amount. Wyllie's equation is based on two phase media
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Migration of Incomplete Walk-Away VSP Data
Authors M.J. Smirnov and G.V. KuzmischevP196 MIGRATION OF INCOMPLETE WALK-AWAY VSP DATA MAXIM. JU. SMIRNOV and GREGORY V. KUZMISCHEV. United Institute of Geology Geophysics and Mineralogy Siberian Branch Russian Academy of Science 3 Koptuga prospect 630090 Novosibirsk Russia 1 Summary. The approach to migration of walk-away VSP data is considered in the paper. Walk-away VSP data frequently contains a limited number of sources. Therefore very strong migration artifacts will appear when using the common migration procedure for such data. This method allows to reduce influence of the artifacts on migration images using a priori information about subsurface structure. The method has been successfully tested on
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Seismic Characterization of Vertical Fractures Described as General Linear-Slip Interfaces
Authors A.V. Bakulin, V. Grechka and I. Tsvankin¡ £ ¥ § © � � © � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � © � � © � � � � � � � © � � � � � � � � � � � � � � ¡ © � � � � � � � � � � � © � � � � � � � � � � � � � �
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A Cross-Matching Scheme for 3D Seismic Data
Authors A. Druzhinin and C. MacBethP202 A CROSS-MATCHING SCHEME FOR 3D SEISMIC DATA ALEXANDER DRUZHININ and COLIN MACBETH Summary 1 A constrained waveform warping transformation for increasing the repeatability of 3D seismic data sets after the least-squares (L2) or RMS matched-filtering is proposed. In addition to the conventional geometrical warping transformation (Rickett and Lumley 1998) the new matched filter can simultaneously fit the local time amplitude and phase of the waveforms during the warping process by using a weighted sum of four traces. A comparative cross equalization of field post-stack data shows that this filter improves the repeatability. Introduction Recently 3D time-lapse seismic data have
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Wavelet Based Volume Attributes for Seismic Interpretation
Authors R.L.C. Van Spaendonck, T.P.H. Steeghs, I. Overeem, F.C.A. Fernandes and J.T. Fokkemap-203 WAVELET BASED VOLUME ATTRIBUTES FOR SEISMIC INTERPRETATION R.L.C. VAN SPAENDONCK 1 T.P.H. STEEGHS 2 I. OVEREEM 1 F.C.A. FERNANDES 3 and J.T. FOKKEMA 1 1 Delft University of Technology Subfaculty of Applied Earth Sciences Mijnbouwstraat 120 2628 RX Delft e-mail: [email protected] 2 TNO Physics and Electronics Laboratory P.O. Box 96864 2509 JG The Hague 3 Rice University Department of Electrical and Computer Engineering 6100 South Main Street Houston TX 77005 Summary Seismic attribute analysis has gone through a major revolution due to the introduction of threedimensional seismic imagery. Features of special interest are the local geometry of the seismic
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