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63rd EAGE Conference & Exhibition
- Conference date: 11 Jun 2001 - 15 Jun 2001
- Location: Amsterdam, Netherlands
- Published: 11 June 2001
201 - 300 of 516 results
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PS-Wave Birefringence Analysis at the Emilio Field for Fracture Characterization
Authors J. Gaiser, E. Loinger, H. Lynn and L. VetriN-07 PS-WAVE BIREFRINGENCE ANALYSIS AT THE EMILIO FIELD FOR FRACTURE CHARACTERIZATION J. GAISER 1 E. LOINGER 2 H. LYNN 3 and L. VETRI 2 Summary 1 3-D converted P to S-waves (PS-waves) provide an excellent opportunity to exploit upgoing shear-wave (S-wave) birefringence (splitting) for delineating reservoir fractures. In azimuthally anisotropic media fracture intensities and orientations are directly related to traveltime differences between the fast and slow S-wave and the polarization direction of the fast S-wave respectively. Birefringent velocity properties of the overburden must be determined and removed prior to estimating fracture properties at target horizons. The Emilio 3-D survey acquired
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Quantitative Use of Pre-Stack Timelapse Seismic for Production History Matching
Authors P. Rowbotham, P. Williamson, D. Marion, G. Janex and O. Gosselin1 N-09 QUANTITATIVE USE OF PRE-STACK TIME- LAPSE SEISMIC FOR PRODUCTION HISTORY MATCHING PETER ROWBOTHAM PAUL WILLIAMSON DOMINIQUE MARION GAEL JANEX and OLIVIER GOSSELIN TotalFinaElf Exploration UK plc Geoscience Research Centre 33 Cavendish Square London W1G OPW UK Abstract In recent years we have witnessed impressive advances in the use of time-lapse seismic data for reservoir management. Most examples have used the seismic in a qualitative or at best semiquantitative manner typically highlighting zones of drainage through TL difference maps. Here we advocate quantitative use of seismic data in the production history matching process through high-resolution inversion of pre-stack depth
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The Role of Petrophysical and Seismic Modelling in Determining the Feasibility, Parameterisation and Sensitivity of Prestack Inverversion
Authors X.-Q. Ma, T. Schulte, A. Pelham and P. HaskeyN-10 THE ROLE OF PETROPHYSICAL AND SEISMIC MODELLING IN DETERMINING THE FEASIBILITY PARAMETERISATION AND SENSITIVITY OF PRESTACK INVERSION 1 XIN-QUAN MA THOMAS SCHULTE ADRIAN PELHAM and PAUL HASKEY Scott Pickford Group Ltd. 7th Floor Leon House 233 High Street Croydon CR0 9XT UK Introduction Prestack seismic inversion can extract not only compressive information but also shear information about a rock. The shear wave information is present from the variation of reflection coefficients with source-receiver spacing (AVO) in multi-offset seismic data. To detect the lithology and fluid content within reservoirs both P- and S-wave properties of a rock are required. The
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Amplitude Versus Offset Classification (AVOC) Using Relative Acoustic Impedance (RAI) Data
By A.N. FoggN-11 AMPLITUDE VERSUS OFFSET CLASSIFICATION (AVOC) USING RELATIVE ACOUSTIC IMPEDANCE (RAI) DATA ANTHONY N. FOGG Hampson-Russell Software Services Ltd Grove House 551 London Road Isleworth Middlesex TW7 4DS UK Introduction Pre-stack seismic data can be difficult to handle due to the large volumes of data involved and the extensive processing and analysis time required. Using only near and far stacks and no velocity or well data this paper demonstrates the theory behind the new AVOC technology (Amplitude Versus Offset Classification) that yields high-resolution seismic volumes which can be interpreted as a post-stack seismic volume. Resolution of the volume exceeds that
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AVO and Elastic Impedance
By S. MallickN-12 AVO AND ELASTIC IMPEDANCE S. MALLICK Summary: Traditional AVO analysis involves computation of the AVO intercept and gradient from a linear fit of P-wave reflection amplitude to the sine square of the angle-of-incidence. This linear fit is based on the approximate P-wave reflection coefficient formulation in intercept-gradient form given by Bortfeld (1961) and Shuey (1985) among others. Under the assumption of a background P-S velocity ratio of two the AVO intercept and gradient values can also be combined to obtain additional AVO attributes such as pseudo S-wave data and Poisson’s ratio contrast. AVO intercept and pseudo S-wave data are
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Interactions between Ambiguities from AVO Inversion and Petrophysical Relations - an Exercise
Authors E. Zamboni and A. MazzottiN013 Interactions between ambiguities from AVO inversion and petrophysical relations: an exercise. A. Mazzotti and E. Zamboni University of Milan Earth Sciences Dept.-Geophysics Via Cicognara 7 20129 Milano Italy 1 Introduction. Seismic inversion techniques applied to real noise contaminated data with limited apertures rarely if ever are capable to yield unique results. Non-linear AVO inversion of single interfaces does not break this rule: depending on the noise level and on the range of available incidence angles the solutions of the inversion may either fall randomly in the parameter space indicating the presence of local minima in the objective function or
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AVO Processing - Myths and Reality
By G. CamboisN-14 AVO PROCESSING – MYTHS AND REALITY Summary 1 AVO processing is meant to make the input data compatible with Shuey’s equation. This task is extremely difficult due to the overly simplistic formulation of the problem compared with the complexity of the real physical experiment. Fortunately the advent of elastic impedance has made it possible to relax some of the processing requirements. Some major concerns (such as amplitude balancing and NMO-stretching) have become almost irrelevant while others that were often overlooked (such as residual-NMO and multiples) have become critical. Introduction Although preserved amplitude processing is a clear requirement for AVO
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CAG and CRP Methodology - a Complement to AVO Calibration in Heterogeneous Medium
Authors J.B. Blanco, C. Borghi and F. SelvaN-15 CAG AND CRP METHODOLOGY – A COMPLEMENT TO AVO CALIBRATION IN HETEROGENEOUS MEDIUM 1 JACQUES BLANCO CHRISTOPHE BORGHI and F. SELVA TOTALFINA ELF Exploration Avenue Larribau 64018 Pau CEDEX France Abstract The AVO technique is widely used for the direct reservoir characterization in terms of lithology and fluids. Its consists of specific processing and analysis/interpretation of pre-stack seismic data. When well information exists it is critical to take advantage of them to quantitatively calibrate the AVO responses. This is the best way to reduce uncertainties on a priori choices regarding the reservoir context and make AVO anomalies interpretation less
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Scaling and Seismic Reflectivity - Implications of Scaling on AVO
More LessN 016 SCALING AND SEISMIC REFLECTIVITY: IMPLICATIONS OF SCALING ON AVO FELIX J. HERRMANN Earth Resources Laboratory EAPS MIT Abstract AVO analysis of seismic data is based on the assumption that transitions in the earth consist of jump discontinuities only. Generalization of these transitions to more realistic transitions shows a drastic change in observed AVO behavior especially for the large angles currently attained by increasing cable lengths. We propose a simple approach that accounts for this anomalous behavior by renormalizing the observed AVO. This approach allows for a separation of the observed AVO effects in terms of a conventional Zoeppritz
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A New Model of Scattering Attenuation - Theory and Application
Authors T.M. Müller and S.A. ShapiroN-017 A NEW MODEL OF SCATTERING ATTENUATION – THEORY AND APPLICATION Summary T.M. MÜLLER and S.A. SHAPIRO Freie Universität Berlin Fachrichtung Geophysik Malteserstr. 74-100 12249 Berlin Germany We present a scattering attenuation model based on the statistical wave propagation theory in random media. This new description of scattering attenuation additionally obeys the causality principle. It practically has no restriction in the frequency domain. The presented formulas allow to quantify scattering attenuation in complex geological regions using simple statistical estimates from well-log data. This knowledge is important for further petrophysical interpretations of reservoir rocks. This description of scattering attenuation can be
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Scaling Behaviour of the Transmission Response of Reservoir Rock - Measurements, Theory and Numerical Simulation
Authors E.D. Mercerat, C.P.A. Wapenaar, J.T. Fokkema, G. Swinnen and M. DillenN 018 SCALING BEHAVIOUR OF THE TRANSMISSION RESPONSE OF RESERVOIR ROCK: MEASUREMENTS THEORY AND NUMERICAL SIMULATION E.D. MERCERAT 1 K. WAPENAAR 2 J.T. FOKKEMA 2 G.SWINNEN 2 and M. DILLEN 2 Introduction 1 International Institute for Aerospace Survey & Earth Sciences (ITC) Division of Exploration Geophysics Hengelostraat 99 PO Box 6 7500 AA Enschede The Netherlands. 2 Delft University of Technology Subfaculty of Applied Earth Sciences A couple of years ago ultrasonic transmission measurements have been carried out on Rotliegend reservoir sandstone samples (Den Boer Dillen Duijndam and Fokkema 1996 EAGE; Swinnen 1997 M.Sc. thesis Leuven / Delft). The experiments
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Combine Effects of Frequency Dependence, Sample Size and Heterogeneities on Acoustic Velocity
More LessN-19 COMBINE EFFECTS OF FREQUENCY DEPENDENCE SAMPLE SIZE AND HETEROGENEITIES ON ACOUSTIC VELOCITY Summary - 1 - In reservoir characterization measurements are made at different scales. Data collected at one scale are used to calibrate measurements at other scales. In order to evaluate possible scale effects on velocity measurements systematic sets of acoustic experiments were applied to different size samples of rocks and synthetic materials. The two analyzed main aspects were the experimental limitations due to the decrease in sample size and the significance of measurement results in relation with the sample characteristics. The results pointed out are: • The
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Does Fluid Viscosity Influence Seismic Velocity?
By M. ChapmanN-20 DOES FLUID VISCOSITY INFLUENCE SEISMIC VELOCITY? MARK CHAPMAN 1 The introduction of the time-lapse methodology requires a clear understanding of how the seismic properties of rock respond to changing reservoir conditions. Perhaps the most fundamental such question is the fluid-substitution problem: the attempt to predict the seismic effect resulting from a change to the saturating fluid. Gassmann's theorem (Gassmann 1951) and its extensions (Brown and Korringa 1975) have traditionally formed the theoretical basis for attempts to solve the fluid-substitution problem in practice. The formal statement of Gassmann's result is: N sat ⎛ N ⎞ ⎜ ⎜1 − N ⎟
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Porosity and Permeability Heterogeneity - Implications for Acoustic Properties
Authors S.J. Hennah, S. Assefa, A.S. Lucas and C. McCannN-21 POROSITY AND PERMEABILITY HETEROGENEITY – IMPLICATIONS FOR ACOUSTIC PROPERTIES S.J. HENNAH S. ASSEFA A.S. LUCAS and C. McCANN. Postgraduate Research Institute for Sedimentology The University of Reading PO Box 227 Whiteknights Reading RG6 6AB UK. Abstract Introduction 1 The necessity for reservoir engineers to maximise recovery from existing fields has led to the development of increasingly sophisticated seismic imaging techniques including time-lapse surveys vertical seismic profiling and cross-hole surveys. The inversion of seismic data to predict hydrocarbon reservoir characteristics requires a detailed knowledge of the relationships between the seismic and petrophysical properties of the reservoir rocks. Whilst it is
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Specific Surface of Cracked Media and Estimation of Porosity by Splitting of Shear Waves
More LessN-22 SPECIFIC SURFACE OF CRACKED MEDIA AND ESTIMATION OF POROSITY BY SPLITTING OF SHEAR WAVES B.P. SIBIRIAKOV The Institute of Geophysics RAS (Sib. div.) Koptyg Avenue 3 Novosibirsk 630090 Russia 1 Summary. The product of specific surface σ0 by average length l of a rectilinear segment of a fracture is linked with porosity f. It is shown that the above mentioned product σ0l is a main factor of decrease of velocities of P and S waves in fractured media. Because (at small value of porosity f) f is the quantity far from being small even at small porosity (not a
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The Corinth Rift Laboratory
Authors I. Moretti, J.P. Delhomme, F. Cornet and P. BernardN-23 THE CORINTH RIFT LABORATORY Summary : A natural laboratory is being created in the Gulf of Corinth by the European Union national and private research centers oil companies and geophysical contractors. The goal is to understand the relationship between faults/fractures fluid flow and fault mechanics. Displacement velocity tilts fluid flow fluid chemistry and stress will be recorded over an area of 30x30 km and at depth on monitored active faults. New permanent sensors are being developed for this project and the results will be integrated in a general model of fluid flow in a faulted and fractured rock with
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Elastic Properties of Cambrian Siliciclastic Rocks from the Baltic Basin
Authors A. Shogenova, S. Sliaupa, A. Jõeleht, V. Rasteniene, K. Kirsimäe, L. Bitjukova, L. Lashkova, A. Zabele, A. Freimanis, P. Hoth and E. HuengesN-24 ELASTIC PROPERTIES OF CAMBRIAN SILICICLASTIC ROCKS FROM THE BALTIC BASIN • A. SHOGENOVA 1 S. SLIAUPA 2 A. JÕELEHT 3 V. RASTENIENE 2 K. KIRSIMÄE 3 L. BITJUKOVA 1 1 L. LASHKOVA 3 A. ZABELE 4 A. FREIMANIS 5 P. HOTH 6 and E. HUENGES 7 1 Institute of Geology at TTU 7 Estonia Ave. 10143 Tallinn Estonia 1 2 Institute of Geology Lithuania 3 Institute of Geology TU Estonia 4 University of Latvia 5 Latvian Development Agency 6 BGR 7 Geoforschungs Zentrum Summary Longitudinal and transversal velocities of Cambrian siliciclastic rocks from the Baltic basin were measured in
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Towards High-Resolution 3D Marine Seismic Surveying Using Boomer Sources
Authors B. Milkereit, C. Mueller, F. Theilen and T. BohlenN-25 TOWARDS HIGH-RESOLUTION 3-D MARINE SEISMIC SURVEYING USING BOOMER SOURCES B. MILKEREIT 1 CF. MUELLER 2 F. THEILEN 1 and T. BOHLEN 1 1 Summary High-frequency 3-D seismic reflection data acquired in shallow marine and lake environments yield continuous maps and cross-sections and provide new constraints on the nature extent and regional distribution of subsurface geology. High-frequency boomer sources show sufficient stability to be used in multi-channel seismic surveys. A 2.5-D feasibility study was successfully conducted in the Baltic Sea revealing shallow gas accumulations and a Pleistocene fluvial channel system beneath unconsolidated sediments. Introduction Extensive tests are required to optimize
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4C-Sensor Orientation Using Multicomponent-SVD Method Applied on Shallow Water Data
Authors J. Meunier, F. Glangeaud and J.-L. MariN-26 4C-SENSOR ORIENTATION USING MULTICOMPONENT-SVD METHOD APPLIED ON SHALLOW WATER DATA F. GLANGEAUD 1 J.L. MARI 2 and J. MEUNIER 3 Abstract 1 In shallow water wave propagation in the low frequency range gives rise to dispersive guided waves. In the presented field example the source signal is generated by air guns which are fired at regular distance interval along a profile. The receiver is a 4-component sensor laid on the sea bottom. SVD method applied on each 4C seismic trace is used to extract the strong dispersive guided wave. The orientation angles for each offset are also computed by
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NMO Correction of Shallow-Seismic Data
Authors J. Brouwer, V. Nijhof and J. TempelsN-27 NMO CORRECTION OF SHALLOW-SEISMIC DATA J. BROUWER V. NIJHOF and J. TEMPELS OYO Center of Applied Geosciences Archimedesbaan 16 3439 ME Nieuwegein The Netherlands Abstract 1 The application of traditional NMO-correction techniques in the processing of shallow-seismic data may result in severe distortion. This distortion is observed as a decrease in frequency content (NMO stretch) or even a total loss of data for steep velocity gradients. It is shown that the observed distortion is introduced by the particular implementation of the traditional NMO correction technique. It is furthermore shown that other techniques that have been proposed in literature suffer
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Multiscale Analysis Revealing the Lateral Variation of Soil Strength from S-Wave Reflection Data
Authors R. Ghose and J.C.M. GoudswaardN-028 MULTISCALE ANALYSIS REVEALING THE LATERAL VARIATION OF SOIL STRENGTH FROM S-WAVE REFLECTION DATA R. GHOSE and J.C.M. GOUDSWAARD Section of Applied Geophysics Centre for Technical Geoscience Delft University of Technology The Netherlands Summary We propose a new approach of spatially integrating shear-wave seismic reflection data reflecting the stiffness distribution to Cone Penetration Test data representing the distribution of strength of soil. The approach is based on extracting the fine scale velocity variation information from the seismic data by a multiangle inversion and then employing a multiscale analysis to the fine-scale velocity function and the cone resistance to characterize the
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A New Approach for the Joint Inversion of Seismic and Geoelectric Data
Authors A. Tillmann and T. Stöcker� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �
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Antarctic Glaciations' Analysis by Reflection and Refraction Tomography
Authors F. Accaino, G. Böhm and G. BrancoliniN-30 ANTARCTIC GLACIATIONS’ ANALYSIS BY REFLECTION AND REFRACTION TOMOGRAPHY GUALTIERO BÖHM GIULIANO BRANCOLINI and FLAVIO ACCAINO 1 OGS Borgo Grotta Gigante 34010 Sgonico TR Italy Abstract The evolution of the Antarctic ice sheet left geological footprints in the shallowest offshore formations: over-compacted and less consolidated sediments in alternate layers reveal a different ice load during the expansion or regression of the ice sheet. We jointly inverted reflected and head waves for detecting the vertical and lateral seismic velocity variation. From our velocity estimate we recognise a major velocity anomaly corresponding to a basin-wide unconformity that we interpret as the result
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HR Seismic Imaging of Geothermal Aquifers
Authors A. Primiero, P. Benedetti, C. Trocca, F. Zgur and N. Di MarzoN-31 HR SEISMIC IMAGING OF GEOTHERMAL AQUIFERS P. BENEDETTI 1 A. PRIMIERO 1 C. TROCCA 1 F. ZGUR 1 N. DI MARZO 2 Summary 1 The costs of High Resolution seismic survey can be reduced by a careful planning and increased productivity. It was successfully employed in the Friuli-Venezia Giulia plain (Northern Italy) for definition of the geothermal reservoirs in the area and planning of wells for hot fluids exploitation. Introduction The presence of two geothermal aquifers (a deep one with temperatures of around 65 °C and a shallow one with max 40 °C) is supposed in the Friuli-Venezia Giulia
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Velocity and Absorption Analysis from Tomographic Sonic Experiments on Ancient Stone Piers
Authors L. Zanzi, E. Cardarelli and M. LualdiN-32 VELOCITY AND ABSORPTION ANALYSIS FROM TOMOGRAPHIC SONIC EXPERIMENTS ON ANCIENT STONE PIERS L. ZANZI 1 E. CARDARELLI 2 and M. LUALDI 1 Abstract 1 Traveltime and spectrum centroid have been backprojected to extract from sonic experiments on ancient stone piers the distribution of velocity and absorption. A feasibility study was necessary to ensure the applicability and the reliability of the absorption results derived from the frequency downshift analysis. The case study consists of 28 tomographic sections executed on 8 massive stone piers of a 17 th century church where a very intensive investigation program was planned to assess the
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Uncertainty Estimation and Error Analysis for Linear Inversion Problems
Authors K. Van Wijk, J.A. Scales and W. NavidiN-33 UNCERTAINTY ESTIMATION AND ERROR ANALYSIS FOR LINEAR INVERSION PROBLEMS Summary K. VAN WIJK 1 J. A. SCALES 1 and W. NAVIDI 2 1 Center for Wave Phenomena Colorado School of Mines Golden CO 80401 USA 2 Department of Mathematics Colorado School of Mines Golden CO 80401 USA Inverse theory concerns the problem of making inferences about physical systems from measurements. Since the measurements are invariably subject to some uncertainty to solve an inverse problem it is necessary to have information about the errors in the observations otherwise it is impossible to say when a feature “fits the data.” In
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Characterization of 4D-Geophysical Data Using a Nonlinear Inversion Algorithm
Authors A. Abubakar, P.M. Van den Berg and J.T. FokkemaN-034 CHARACTERIZATION OF 4D-GEOPHYSICAL DATA USING A NONLINEAR INVERSION ALGORITHM A. ABUBAKAR P. M. VAN DEN BERG and J. T. FOKKEMA Centre for Technical Geoscience Delft University of Technology Mekelweg 4 2628 CD Delft The Netherlands Introduction Characterization of time-lapse 3D seismic data also known as 4D seismic is based on a difference image of the subsurface from two comparable surveys denoted by the reference state and the monitor state respectively. Both states are separated by a certain time span. Then from this difference observation conclusions are drawn with respect to the change of the medium which can be related
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Bayesian Look-Ahead Inversion of Walkaway Vertical Seismic Profiles
Authors A. Malinverno and W.S. LeaneyN-35 BAYESIAN LOOK-AHEAD INVERSION OF WALKAWAY VERTICAL SEISMIC PROFILES Summary 1 We describe a method to invert a walkaway VSP (WVSP) data set and predict VP VS and density below a receiver. We use a Bayesian approach where one first sets a prior distribution for VP VS and density based on information from nearby well logs (which contain information on the overall variability of and correlations among VP VS and density) and on the normal moveout in the WVSP data (which contain information on the long-wavelength variation of VP). We then obtain a posterior distribution of VP VS and density
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Bayesian Wavelet Estimation from Seismic and Well Log Data
More LessN-036 BAYESIAN WAVELET ESTIMATION FROM SEISMIC AND WELL LOG DATA ARILD BULAND 1 and HENNING OMRE 2 Abstract 1 Statoil Research Centre Postuttak N-7005 Trondheim Norway 2 Norwegian University of Science and Technology N-7491 Trondheim Norway A Bayesian method for wavelet estimation from seismic and well data is developed. The forward model is based on the convolution model where the reflectivity is calculated from the well logs. The estimated wavelet is given as a probability density function such that uncertainty in the wavelet is an integrated part of the solution. Seismic noise and possible mistie between the seismic and well
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Shallow Waterflow Detection Using Prestack Inversion
Authors R. De Kok, N. Dutta, S. Mallick, R. Utech and R. VauthrinN-37 SHALLOW WATERFLOW DETECTION USING PRESTACK INVERSION Summary Highly porous sands prone to flowing when drilled (shallow waterflow sands) pose a serious risk and have cost the oil industry hundreds of millions of dollars to date. Detection of these shallow waterflow prone sands is important for reducing environmental risks and commercial losses. The use of standard seismic data for detection has been explored and found successful at the Ursa site in the Mississippi Canyon area of the Gulf of Mexico. Although the data quality of the selected set is at or below average reprocessing at 2 ms yielded sufficient quality
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Modelling of Hydrate Phase Equilibria in Porous Media
Authors K.K. Østergaard, M. Llamedo and B. TohidiO-01 MODELLING OF HYDRATE PHASE EQUILIBRIA IN POROUS MEDIA K.K. ØSTERGAARD M. LLAMEDO and B. TOHIDI Heriot-Watt University Edinburgh EH14 4AS UK Considering the ever-increasing importance of gas hydrates in marine sediments it is crucial to gain a better understanding of their formation and decomposition in porous media. Before hydrate formation and decomposition in complex marine sediment systems can be successfully described it is necessary to understand the basic interactions between fluids hydrates and the porous medium. One way of obtaining such information is by performing experiments in the controlled laboratory environment using well-defined porous media and fluids. Such data
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Structural Transition of a Natural Gas Clathrate Hydrate
Authors M.D. Jager and E.D. Sloan Jr.O-02 STRUCTURAL TRANSITION OF A NATURAL GAS CLATHRATE HYDRATE M.D. JAGER and E.D. SLOAN Jr. Center for Hydrate research Colorado School of Mines 1500 Illinois St. Golden CO 80401 USA 1. Introduction 1 One of the main concerns in flow assurance of offshore pipelines is the formation of solid clathrate hydrates. Clathrate hydrates are crystalline compounds of water in a hydrogen-bonded lattice with cavities in which hydrocarbon molecules are trapped. Small hydrocarbon molecules methane through butane are ideally suited to form such compounds under elevated pressure in the presence of water. Thus any pipeline that transports hydrocarbons and water has
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The Assessment of Gas Hydrate Deposits through Electrical Remote Sounding
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Investigating Gas Hydrates Using Seismic Multi-Component Ocean Bottom Cable Data
Authors K. Andreassen, K.A. Berteussen, J. Mienert, H. Sognnes, K. Henneberg and J. LanghammerAbstract 1 O-04 INVESTIGATING GAS HYDRATES USING SEISMIC MULTI-COMPONENT OCEAN BOTTOM CABLE DATA AUTHORS 1 2 1 3 3 3 K. ANDREASSEN K.A.BERTEUSSEN J. MIENERT H. SOGNNES K. HENNEBERG AND J. LANGHAMMER Address 1 Department of Geology University of Tromsø N-9037 Tromso Norway 2 PGS 16010 Barkers Point Lane Suite 600 Houston Texas 77079 USA 3 PGS Strandveien 4 1366 Lysaker Norway Estimation of gas-hydrate concentration from seismic velocities will depend strongly on the micro-scale hydrate distribution in the sediment pore space. Shear-wave seismic may be the key data to decide the microscale distribution of gas hydrate in the pore
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Resource Evaluation of Marine Gas Hydrates by Seafloor Compliance
Authors E.C. Willoughby and R.N. EdwardsO-05 RESOURCE EVALUATION OF MARINE GAS HYDRATES BY SEAFLOOR COMPLIANCE 1 ELEANOR C. WILLOUGHBY and R. NIGEL EDWARDS Department of Physics University of Toronto 60 St. George St. Toronto Ont M5S 1A7 Canada SUMMARY: Methane hydrate changes the physical properties especially by increasing shear strength of the marine sediments in which it is found. Compliance is defined as the transfer function between the vertical displacement of the seafloor and the corresponding pressure expressed as a function of frequency. Since it is sensitive to the elastic parameters of the underlying sediments particularly the shear modulus it is an apt tool for
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Dissociation of Methane Hydrate Slurries
Authors A. Halouane and A. SinquinO-07 DISSOCIATION OF METHANE HYDRATE SLURRIES A. HALOUANE and A. SINQUIN Institut Français du Pétrole 1 & 4 Avenue Bois Préau 92852 Rueil Malmaison CEDEX France Abstract 1 Methane hydrate deposits have been considered in the last 25 years as substantial future resources. They are estimated to account for 53% of the total organic carbon in the Earth. To further exploit this resource knowledge of the hydrate dissociation process will be essential for the production of gas from marine sediments and permafrost associated gas hydrates. In an attempt to study this process a high pressure stirred semi-batch reactor cooled by
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The Effect of Faults on the 3D Connectivity of Coal Measure Sandstones - the East Pennine Coalfield, UK
Authors W.R. Bailey, T. Manzocchi, J.J. Walsh, J. Strand, P.A.R. Nell, K. Keogh, D. Hodgetts, S. Flint and J. RipponO-09 THE EFFECT OF FAULTS ON THE 3-D CONNECTIVITY OF COAL MEASURE SANDSTONES – THE EAST PENNINE COALFIELD U.K W. R. BAILEY 1 T. MANZOCCHI 1 J. J. WALSH 1 J. STRAND 1 P. A. R. NELL 3 K. KEOGH 2 D. HODGETTS 2 S. FLINT 2 and J. RIPPON 4 1 Fault Analysis Group Department of Geology University College Dublin Ireland 2 Stratigraphy Group Department of Earth Sciences University of Liverpool 3 Badley Earth Sciences 4 International Mining Consultants Summary 1 The connectivity of sand bodies has been tested in a deterministic high resolution 3-D geocellular model (15 million
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Estimation of Fracture Orientation, Offshore Abu Dhabi
Authors G. Roberts, R. Wombell, D. Gray, A. Al-Shamsi, O. Suwaina, G. Ajlani, A. Ebed and M. Al-KaabiO-10 ESTIMATION OF FRACTURE ORIENTATION OFFSHORE ABU DHABI 1 GRAHAM ROBERTS 1 RICHARD WOMBELL 1 DAVID GRAY 2 ALI AL-SHAMSI 3 OMAR SUWAINA 3 GHIATH AJLANI 3 ATEF EBED 3 and M. AL-KAABI 3 1 Veritas DGC Limited Manor Royal Estate Crawley West Sussex RH10 2QR UK 2 Veritas DGC Inc 3 ADNOC Summary A 3D OBC survey was acquired over an offshore Field in Abu Dhabi Middle East during 2000. The acquisition geometry of the survey provides data that is well sampled with respect to azimuth and offset range. Sensitivity analysis indicated that the data is suitable for azimuthal
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Study of 3D Distribution of Geomedium Fracturing by Side-View Seismic Location Method (SVSL)
Authors B.Y. Meltchouk, O.L. Kouznetsov, I.S. Faizulline, I.A. Chirkine, S.I. Slionkin and G.V. KashirinO-11 STUDY OF 3-D DISTRIBUTION OF GEOMEDIUM FRACTURING BY SIDE-VIEW SEISMIC LOCATION METHOD (SVSL) Abstract 1 Presented is a new Russian seismic technology for studying the geomedium fracturing from scattered waves by a Side-View Seismic Location method (SVSL). As compared to widely used seismic methods SVSL has a number of original specific features: physical basics of the method – side-view location; type of detected seismic waves – scattered seismic waves; technology of field operations - two-position seismic locator positioned outside the area under study; algorithms and software applied in data processing – conjugated (dual) focusing of source and receiver apertures;
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Investigating Matrix and Fracture Flow - Initial Studies for Fracture Upscaling
Authors M.A. Reynolds, G.D. Couples, G.E. Pickup and H. LewisO-12 INVESTIGATING MATRIX & FRACTURE FLOW – INITIAL STUDIES FOR FRACTURE UPSCALING Abstract 1 MARK A. REYNOLDS GARY D. COUPLES GILLIAN E. PICKUP and HELEN LEWIS Department of Petroleum Engineering Heriot - Watt University Edinburgh EH14 4AS UK While trying to develop upscaling methods for simulating multi - phase flow in fractured reservoirs we have been exploring a variety of simulation techniques. One of our prime objectives is to ensure that the methods capture the physics of fluid flow. On the small - scale (cm) our preliminary assessment of the standard “dual porosity / dual permeability” method is that it
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The Use of Discrete Fracture Models to Constrain Full Field Fluid Flow Simulations
Authors J.M. Daniel, B. Gauthier, M.C. Cacas, O. Lerat and S. SardaO-13 THE USE OF DISCRETE FRACTURE MODELS TO CONSTRAIN FULL FIELD FLUID FLOW SIMULATIONS J.M. DANIEL 1 B. GAUTHIER 2 M.C. CACAS 1 O. LERAT 1 and S. SARDA 1 Abstract Summary 1 The aim of this presentation is to describe how local discrete fracture models can be use to fill the reservoir grid built for fluid flow simulation of fractured reservoirs. The application of the proposed methodology to a fractured carbonate reservoir is used to highlight the main advantage of the proposed methodology and the type of reservoir characteristics it can reveal. Furthermore it demonstrates that even in a
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Fluid Property Prediction in the Siri Trend - Did We Get It Right ?
Authors C. Zwach and R. Di PrimioO-15 FLUID PROPERTY PREDICTION IN THE SIRI TREND – DID WE GET IT RIGHT? C. ZWACH AND R. DI PRIMIO Summary 1 A combination of basin modelling and PVT modelling was used for the assessment of migration pathways efficiency and fluid property prediction in a Paleocene carrier system of the Norwegian-Danish basin. The area under study included the Siri oil field which is assumed to be charged via long distance migration from the generative kitchen area in the Tail End Graben. Detailed analysis of the carrier system revealed locally variable sensitivity of migration pathways through geologic time. The most robust
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History of Petroleum Generation and Migration in the Broad Fourteens Basin
Authors J.M. Verweij, H.J. Simmelink, R.T. Van Balen, P. David and F. Van BergenO-16 HISTORY OF PETROLEUM GENERATION AND MIGRATION IN THE BROAD FOURTEENS BASIN J.M. VERWEIJ 1 H.J. SIMMELINK 1 R.T. VAN BALEN 2 P. DAVID 1 and F. VAN BERGEN 1 Abstract 1 Results of data analysis of the Broad Fourteens Basin combined with 2D basin modelling indicate the existence of very distinct petroleum systems in the basin. Temperature maturation and petroleum generation history as well as migration characteristics vary over short distances and are shown to be closely related to the geodynamic history of the basin. Modelling results support the concept of the role of time-dependent permeability of fault and
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Application of Pre-Stack Wave Equation Datuming to Remove Interface Scattering in Sub-Basalt Imaging
Authors F. Martini and C.J. BeanO-17 APPLICATION OF PRE-STACK WAVE EQUATION DATUMING TO REMOVE INTERFACE SCATTERING IN SUB-BASALT IMAGING F. MARTINI and C.J. BEAN Dublin University College Belfield Dublin 4 Ireland 1 Summary Interface roughness affects deeper reflectors imaging and continuity. The effect is even stronger when a moderate to strong acoustic impedance contrast is present in the shallow surface. Sub-basalt imaging has been a problem of general interest in the last few years in petroleum industry. Previous work has already demonstrated that energy transmission into and propagation though the basalt does occur. The imaging problem in sub basalt imaging seems to be related mostly
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Sub-Basalt Mapping Along the North Atlantic Volcanic Province (NAVP) - The Faeroes, Møre and Vøring Margins
Authors T. Raum, B. Myhren, R. Mjelde, P. Digranes and H. ShimamuraO-18 SUB-BASALT MAPPING ALONG THE NORTH ATLANTIC VOLCANIC PROVINCE (NAVP) - THE FAEROES MØRE AND VØRING MARGINS 1 T. RAUM 1 B. MYHREN 1 R. MJELDE 1 P. DIGRANES 2 and H. SHIMAMURA 3 1 Bergen University 5007 Bergen Norway 2 Statoil 3 Hokkaido University Introduction The seismic method is the main geophysical tool to explore volcanic margins. However a common problem is how to image the crust below the pervasive extrusive and intrusive sequences characteristic for these areas. If a layer of high velocity/density appear relatively shallow in the sedimentary column conventional multichannel surface seismic (MCS) acquisition methods suffers
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Sub-Basalt Imaging Using a Full Elastic Wavefield Inversion Scheme
Authors Y. Freudenreich, S. Singh and P. BartonO-19 SUB-BASALT IMAGING USING A FULL ELASTIC WAVEFIELD INVERSION SCHEME Abstract 1 As the use of wide-aperture seismic surveying is becoming more established in areas of hydrocarbon interest the importance of mode converted waves is increasing. Although the treatment of shear waves can make an efficient contribution to the understanding of the physical properties of the subsurface a conventional acoustic approach is inadequate to handle these elastic parameters. In this paper an elastic finite difference scheme has been implemented to perform an inversion of both P-wave and S-wave velocities. Until now such inversions have been limited to near offset seismic
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Faeroe Sub-Basalt Seismic Imaging - a New Iterative Time Processing Approach
Authors L. Barzaghi, D. Calcagni, M. Passolunghi and S. SandroniO-20 FAEROE SUB-BASALT SEISMIC IMAGING – A NEW ITERATIVE TIME PROCESSING APPROACH L. BARZAGHI D. CALCAGNI M. PASSOLUNGHI and S. SANDRONI Eni S.p.A. Agip Division Via dell’Unione Europea 3 20097 San Donato Milanese MI Italy Abstract Summary The imaging of sedimentary sequences laying beneath strongly absorbing formations such as the Faeroe Basin Basalt Body can be improved by processing seismic data using a non conventional approach. P-S converted waves generated at the interface between formations with strong velocity difference maintain a higher content of energy with respect to the standard P transmitted waves. A modelling procedure based on synthetic data
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A Viscoelastic Model of Seismic Wave Attenuation in Anisotropic Rocks
By A.J. HanygaO-21 A VISCOELASTIC MODEL OF SEISMIC WAVE ATTENUATION IN ANISOTROPIC ROCKS A. HANYGA Institute of Solid Earth Physics University of Bergen All’egaten 41 N5007 Bergen Summary An anisotropic viscoelastic model of seismic attenuation is presented. The model has some important properties of physical models but is amenable to rigorous mathematical analysis and has a more economic parameterization. It is also adapted to FD numerical and ray-asymptotic solution. Introduction A physically realistic model of seismic wave attenuation must account for global and local porous flow double porosity partial saturation scattering and fast-to-slow wave conversion. This brings in a number of parameters
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Fast Wavefield Simulation in 3D Heterogeneous Elastic Media with Kirchhoff Approximation
Authors P. Zhang, M. Alerini and G. Lambaréthe points satisfying Snell’s law). So one of the most important things in our numerical implementation is to determine the area on which the integral will be implemented. For this purpose ¥ we define � � � � � ¡ £ ¥ � ¨ ¥ § ¨ ¥ � � ¥ the vector on each coarse grid point. Once the scalar � product of ¥ and the � normal vector of the interface is greater than the threshold the integral will be computed on the fine cells around the coarse grid point (figure 1b). Numerical example We only consider a
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2D Elastic Modelling with Efficient Mixed Finite Elements
Authors S. Fauqueux and G. Cohen0-023 2D ELASTIC MODELLING WITH EFFICIENT MIXED FINITE ELEMENTS G. COHEN 1 and S. FAUQUEUX 2 1 Abstract We propose to model full elastic wave propagation in 2D anisotropic elastic media by a Mixed Finite Elements Method with mass-lumping. This method offers a gain of storage and time computation compared to more classical ones and thus should enable us to handle realistic 2D and 3D seismic surveys. Introduction We propose to develop a modelling tool which aims to take count of the specificities of the new seismic prospects : large 2D and 3D realistic models with complex and irregular topographies
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Sobolev Scalar Products in the Construction of Velocity Models
More LessO-24 SOBOLOV SCALAR PRODUCTS IN THE CONSTRUCTION OF VELOCITY MODELS Summary 1 P. BULANT and l. KLIMES Charles University Department of Geophysics Ke Karlovu 3 121 16 Praha 2 Czech Republic The minimization of the Sobolev norm during linearized inversion of given data enables to control the model parameters unresolved by the data being fitted. Even if a reasonably looking model can be obtained without minimizing the Sobolev norm it may be too rough for some computational methods. We may construct models optimally smooth for given computational methods by minimizing the corresponding Sobolev norm during the inversion. Probably the smoothest
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Challenges of Porosity Based Pore Pressure Prediction
More LessO-25 CHALLENGES OF POROSITY BASED PORE PRESSURE PREDICTION DR. R. E. SWARBRICK 1 GeoPOP University of Durham Department of Geological Sciences South Road Durham DH1 3LE UK Abstract Porosity is used as a rock property implicitly reflecting the degree of compaction of sediment. The porosity values may be derived from wireline response or a porosity attribute may be used directly for example velocity data derived from seismic. Where undercompaction occurs due to fluid retention and overpressure porosity is retained above the level referred to as “normal compaction”. Hence a methodology has been developed which can work well in low temperature
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Compaction Model for Quartzose Sandstones - Application to the Garn Formation, Haltenbanken, Mid-Norwegian Continental Shelf - Part I - Theory
Authors F. Schneider and S. HayO-26 COMPACTION MODEL FOR QUARTZOSE SANDSTONES. APPLICATION TO THE GARN FORMATION HALTENBANKEN MID- NORWEGIAN CONTINENTAL SHELF PART I – THEORY F. SCHNEIDER 1 and S. HAY 2 1 1 Institut Français du Pétrole 1 & 4 avenue de Bois-Préau 92506 Rueil-Malmaison France 2 Statoil Abstract The compaction of quartzose sandstones is described by a macroscopical visco-elasto-plastic model derived from microscopical considerations. This model considers that the reduction of total porosity is related to the variation of the relative cemented volume and to the variation of the relative intergrain volume. Furthermore we consider that the variations of these two petrophysical parameters
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Compaction Model for Quartzose Sandstones - Application to the Garn Formation, Haltenbanken, Mid-Norwegian Continental Shelf - Part II - Testing
Authors S. Hay and F. SchneiderO-27 COMPACTION MODEL FOR QUARTZOSE SANDSTONES. APPLICATION TO THE GARN FORMATION HALTENBANKEN MID- NORWEGIAN CONTINENTAL SHELF PART II – TESTING S. HAY 1 and F. SCHNEIDER 2 Abstract 1 1 Statoil 4035 Stavanger Norway 2 Institut Français du Pétrole The visco-elasto-plastic model for chemical compaction described by Schneider & Hay (2001) has been tested in the Haltenbanken area off Mid Norway and appears to be suitable for use in a fully coupled basin scale simulator. In the case study presented here we show that we can satisfactorily model observed phenomena such as porosity overpressures and hydrocarbon distribution. We also show
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Modelling Lateral Fluid Flow in the Smørbukk Area, Offshore Norway
More LessO-28 MODELLING LATERAL FLUID FLOW IN THE SMØRBUKK AREA OFFSHORE NORWAY Abstract 1 H. BORGE 1 and E. VIK 2 1 SINTEF Petroleum Research 7465 TRONDHEIM Norway 2 STATOIL The Halten Terrace offshore Norway consists of three pressure regimes: A highly overpressured (>200 bar) western part an intermediately pressure (75-200 bar) region in the south and a normally pressured (0-75 bar) eastern flank. The Smørbukk and Lavrans fields are located within the normally pressured region adjacent to the fault that separates the highly and normally pressured regimes. The observed overpressures within these two fields vary both vertically and laterally (Table
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Cretaceous - Palaeogene Inversion Tectonics in the Danish Central Graben
Authors O.V. Vejbaek and C. AndersenO-29 Cretaceous - Palaeogene Inversion Tectonics in the Danish Central Graben O. V. VEJBÆK and C. ANDERSEN Geological Survey of Denmark and Greenland (GEUS) Thoravej 8 DK2400 Copenhagen NV Denmark 1 SUMMARY Structural analysis of the Upper Cretaceous to Palaeogene succession in the Danish Central Graben suggests continuous inversion heralded in the Late Hauterivian and continuing into Palaeogene times with phases of increased intensity: 1) latest Santonian 2) Mid Campanian 3) late Maastrichtian 4) Late Paleocene -Eocene and 5) Early Oligocene. Phases 1 through 3 are sub-Hercynian and phases 4 and 5 are Laramide according to the nomenclature used for
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Geomechanical Modelling of Compressive Stress and Overpressures in Inverted Basins
Authors H.J. Simmelink, B. Orlic and J.D. van WeesO-30 GEOMECHANICAL MODELLING OF COMPRESSIVE STRESS AND OVERPRESSURES IN INVERTED BASINS Abstract 1 Until now there is a lack of knowledge on quantified compressive tectonic stress and the impact on the development of overpressures. In this study geomechanical modelling of basin inversion was done to asses the feasability of the modelling tool DIANA for improved quantitative insight in the magnitude of horizontal stresses in a compressive regime in relation to basin geometry and the role of pore fluids. Subsequently the impact of these compressive stresses on overpressure within the sediments was quantified. Introduction H.J SIMMELINK B. ORLIC and J.D. VAN
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The Effect of Chemical Compaction on Fluid Overpressure Development and Seal Integrity
Authors H.M. Helset, J.C. Matthews and P.H.M. ReemstO-31 THE EFFECT OF CHEMICAL COMPACTION ON FLUID OVERPRESSURE DEVELOPMENT AND SEAL INTEGRITY H.M. HELSET J.C. MATTHEWS and P.H.M. REEMST Summary We demonstrate the importance of chemical compaction on porosity loss rates and overpressure development in case studies from the Gulf of Mexico and from the mid-Norway Halten Terrace. Porosity loss rates due to chemical compaction may exceed porosity loss rates corresponding to mechanical compaction at deep burial. Depending on the basin setting more than 50% of the present day overpressure can be attributed to chemical compaction processes. Our model of fluid overpressure incorporates chemical compaction of sediments including quartz
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Mudstone Compaction and Its Influence on Overpressure Generation in the North Sea - a 3D Case Study
Authors H. Synofzik, S. Hansen and T. HantschelO-32 MUDSTONE COMPACTION AND ITS INFLUENCE ON OVERPRESSURE GENERATION IN THE NORTH SEA – A 3D CASE STUDY H. SYNOFZIK 1 S. HANSEN 2 and T. HANTSCHEL 1 1 Integrated Exploration Systems Bastionstrasse 11-19 52428 Juelich Germany 2 Norsk Hydro Summary Mudstones are one of the least permeable lithologies in most sedimentary sequences. Therefore mudstones can operate as seals leading to abnormal overpressures. It will be shown with respect to a 3D study in the North Sea that overpressure can be predicted by using basin modeling techniques. A compaction model for mudstones (Yang and Aplin 1995) that depends strongly on
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4D Overpressure Modelling and Prospectivity - an Example from the North Sea
O-33 4D OVERPRESSURE MODELLING AND PROSPECTIVITY – AN EXAMPLE FROM THE NORTH SEA 1 M.R. GILES E. DUFOUR L. SANCHEZ-RODRIGUEZ G.R. COCKSWORTH S. BETTEMBOURG J.F. McNUTT P. KUKLA S.L. INDRELID and M.C. de JONG Shell International E&P Volmerlaan 8 PO Box 60 2280 AB Rijswijk The Netherlands Abstract As basins around the world are moving into a higher state of maturation the shallower and easier targets will become exhausted. An increased push towards the deeper prospects where there is a greater probability of encountering hard geopressures is becoming reality for more and more areas in the exploration portfolio. It is
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Thermo-Chemical Models for Silicate Diagenesis, Overpressure and Hydrocarbon Resource Distributions - The Gulf of Mexico Evidence
Authors P.H. Nadeau, P.A. Bjørkum and O. WalderhaugO-34 THERMO-CHEMICAL MODELS FOR SILICATE DIAGENESIS OVERPRESSURE AND HYDROCARBON MIGRATION – THE GULF OF MEXICO EVIDENCE P.H. NADEAU P.A. BJØRKUM and O. WALDERHAUG 1 Statoil 4035 Stavanger Norway Abstract Over the last 15 years geochemical models for silicate crystal growth have been developed for predicting the impact of clay diagenesis and quartz cementation on porosity/permeability evolution in sedimentary basins (Nadeau et al. 1985; Walderhaug 1994 1996; Oelkers et al. 1996; Bjørkum et al. 1998). These models indicate that precipitation of diagenetic clay minerals at temperatures > 60°C result in severe permeability reductions in shales/mudstones rendering the affected sedimentary sections prone
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LOPs - "Minimum Stress Gradients" and In-Situ Stress-Pore Pressure Coupling
Authors A.J. White and R.E. SwarbrickO-35 LOPs: “MINIMUM STRESS GRADIENTS” AND IN-SITU STRESS-PORE PRESSURE COUPLING (1) Summary 1 Leak-Off Pressure (LOP) data from six contrasting basins have been examined and plotted on stressdepth plots to establish the lower-bound to LOPs which are proxies for the minimum stress (S3) gradient. Results show these lower-bound trends deviate towards the lithostat with depth in all instances and that the tectonic regime does not effect their shape and magnitude. A subset of the LOP data were paired with pore pressure (Pp) measurements to investigate the extent of Sh-Pp coupling where overpressure increases horizontal stress magnitude. Four of the six
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3D Pore Pressure Prediction in the Columbus Basin, Offshore Trinidad and Tobago
Authors J.H. Snijder, D. Dickson, A. Hillier, A. Litvin, C. Gregory and P. CrookallO-36 3D PORE PRESSURE PREDICTION IN THE COLUMBUS BASIN OFFSHORE TRINIDAD AND TOBAGO Abstract BG Group and Paradigm Geophysical have carried out a 3D Pore Pressure Prediction study over part of the Columbus Basin Offshore Trinidad and Tobago. 1 J.H. SNIJDER 1 D. DICKSON 1 A. HILLIER 1 A. LITVIN 2 C. GREGORY 2 and P. CROOKALL 2 1 BG Group 100 Thames Valley Park Drive Reading RG6 1PT UK 2 Paradigm Geophysical The Columbus basin contains some 20 000 ft. of Plio-Pleistocene clastic sediments and a substantial number of oil and gas fields which have been discovered by BG
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Modelling of Overpressure Generation and Its Implications for Hydrocarbon Migration and Leakage
Authors A. Tommeras, O. Sylta, O. Lonne and T. BergO-37 MODELLING OF OVERPRESSURE GENERATION AND ITS IMPLICATIONS FOR HYDROCARBON MIGRATION AND LEAKAGE Abstract High resolution secondary migration modelling of oil and gas in the Northern North Sea has been performed along upper Jurassic carriers. The modelling has been performed both on a regional and on a block-specific scale and provides prediction of hydrocarbon phases within the mapped prospects at reservoir level. 1 An important aspect of the simulations is pressure compartment modelling. In this work we demonstrate how pressure modelling predicts high overpressures to be generated locally by diagenetic processes within isolated fault compartments. Further we show how the
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Iterative Solvers for Frequency Domain (Visco) Acoustic Modeling of Seismic Waves
By I. SteklP001 ITERATIVE SOLVERS FOR FREQUENCY DOMAIN (VISCO) ACOUSTIC MODELING OF SEISMIC WAVES I. STEKL Summary 1 In order to perform 3D simulations on the hardware available at the moment current approaches in frequency domain are not suitable due to a large amount of memory required to invert the matrix. Point iterative solvers are not converging quickly or not converging at all in the case of the highly oscillatory solutions such is the one of the frequency domain wave equation. In this work I present the results obtained using the appropriate block iterative solver. Frequency domain modelling approach is interesting due
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Finite-Difference Perturbation Method for 3D Anisotropic Media
Authors S.M. Soukina, D. Gajewski and B.M. KashtanP-002 SUMMARY FINITE-DIFFERENCE PERTURBATION METHOD FOR 3-D ANISOTROPIC MEDIA S. M. SOUKINA 1 D. GAJEWSKI 1 and B. M. KASHTAN 2 1 Institute of Geophysics University of Hamburg Bundesstr. 55 20146 Germany 2 St.Petersburg State University To compute the traveltime of seismic waves in a general anisotropic medium it is possible to use a perturbation approach which is based on approximating an anisotropic medium by a simpler analytically treatable reference medium. The isotropic reference medium works well for anisotropies of up to 10%. Some materials can exhibit a stronger anisotropy (e.g. shales). In this case it is possible to consider
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Sampling Issues in the Reflectivity Method for General Anisotropic Media
Authors A. Grandi, G. Bernasconi and G. DrufucaP-003 SAMPLING ISSUES IN THE REFLECTIVITY METHOD FOR GENERAL ANISOTROPIC MEDIA G. BERNASCONI G. DRUFUCA A. GRANDI Politecnico di Milano Dipartimento di Elettronica e Informazione Piazza Leonardo Da Vinci 32 20133 Milan Italy Summary 1 1 The reflectivity method for the computation of synthetic seismograms in layered isotropic media is widely used but in anisotropic media it requires a relevant number of computations because propagation becomes a 3D problem. To reduce the computation time we suggest to sample horizontal wavenumbers with a polar grid: anti-aliasing conditions are less strict than in Cartesian coordinates allowing a smaller sampling. Introduction For isotropic
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Investigations of Elastic Waves Propagation in Models of Sands Sediments
Authors E.B. Sibiriakov and V.A. KulikovP004 INVESTIGATIONS OF ELASTIC WAVES PROPAGATION IN MODELS OF SANDS SEDIMENTS E.B. SIBIRIAKOV and V.A. KULIKOV The Institute of Geophysics RAS (Sib. div.) Koptyg Avenue 3 6630090 Novosibirsk Russia Summary. We present a new approach to describe physical deforming processes in microinhomogeneous media in general in particularly sands sediments. Our approach is based on examination of individual interactions between particles. After it we used a new method of averaging of field forces for chaotic orientation of grains. The theoretical results are: velocity of P and S waves depends not only on average elastic modules of grains and porosity but also
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Numerical Viscoelastic Modeling by Spectral Laguerre Method
Authors B.G. Mikhailenko, A.A. Mikhailov and G.V. KonyukhP005 NUMERICAL VISCOELASTIC MODELING BY SPECTRAL LAGUERRE METHOD 1 Summary The wave propagation in real media can be described within the theory of linear viscoelasticity. The presence of a convolutional integral in Boltzmann's superposition principle involves the main difficulties in implementing the direct numerical methods in the time domain. The paper presents an efficient algorithm based on the application of the spectral Laguerre method for approximation of temporal derivatives and convolution as applied to the problem of seismic wave propagation in the heterogeneous viscoelastic medium. Introduction The paper presents the new efficient algorithm based on the application of the spectral
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Parallel 3D Viscoelastic Finite Difference Seismic Modelling
Authors T. Bohlen and B. MilkereitP 006 PARALLEL 3-D VISCOELASTIC FINITE-DIFFERENCE SEISMIC MODELLING TH. BOHLEN and B. MILKEREIT Institute of Geosciences Geophysics Kiel University Otto-Hahn-Platz 1 24118 Kiel Germany Summary Computational power has advanced to a state where we can begin to perform wavefield simulations for realistic (complex) 3D earth models at frequencies of interest to both seismologists and engineers. On serial plattforms however 3-D calculations are still computationally very expensive. To make use of the efficiency of modern network computers we implemented parallel 3-D elastic/viscoelastic FD codes which allow to distribute the work load among several PCs or workstations connected via standard ethernet in
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3D Physical Modelling
Authors G. Blacquière and A.W.F. Volker3 ' 3+<6 &$/ 02'(// 1* G. BLACQUIÈRE and A.W.F. VOLKER $EVWUDFW 1 Despite the rapid increase in affordable computational power numerical modelling must still acknowledge the superiority of physical modelling in the case of full-size 3-D seismic data sets. In this paper we address our physical modelling facility in Delft and the improvements we realised in the last several years. The various aspects in physical modelling are: the building of a realistic scale model the definition of an acquisition geometry the generation of a source signal and the data acquisition. Each of these aspects requires its own specialised skills
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3D Traveltime and Migration Weight Computation Using Wavefront Oriented Ray Tracing
Authors R. Coman and D. GajewskiP008 3DTRAVELTIME ANDMIGRATION WEIGHT COMPUTATION USING WAVEFRONT ORIENTED RAY TRACING SUMMARY R. COMAN andD.GAJEWSKI Instituteof Geophysics Universityof Hamburg Bundesstr. 55 20146Hamburg Germany We present a wavefront oriented ray-tracing (WRT) technique for computing traveltimes and migration weights in a smooth 3D velocity model. In this method we propagate a wavefront stepwise through the model and interpolate output quantities (ray quantities e.g. traveltimes slownesses) from rays to gridpoints. Our technique is based only on kinematic ray tracing which is sufficient for the computation of migration weights using finite differences. The computational efficiency is increased by (1) using only kinematic ray tracing (2)
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Accurate Seismic Traveltime Approximation at all Offsets
Authors E. Causse and K. HokstadP009 ACCURATE SEISMIC TRAVELTIME APPROXIMATION AT ALL OFFSETS E. CAUSSE and K. HOKSTAD SINTEF Petroleum Research N-7034 Trondheim Norway. Introduction In conventional reflection seismics data are usually stacked along hyperbolae. However the hyperbolic approximation is generally too inaccurate in the presence of anisotropy or wave mode conversions or in wide-aperture surveys e.g. for subbasalt exploration. One solution to refine the hyperbolic approximation is to use more than two terms of the Taner and Koehler (1969) series: t 2 ' a 0 + a 2 x 2 + a 4 x 4 + a 6 x 6 :::� (1) where x
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Seismic-Wave Modelling of a 3D SWD Survey
Authors L. Petronio, F. Poletto, J. Carcione, G. Seriani, A. Luca and F. MirandaP010 SEISMIC-WAVE MODELLING OF A 3D SWD SURVEY L. PETRONIO 1 F. POLETTO 1 J. CARCIONE 1 G. SERIANI 1 A.LUCA 2 and F.MIRANDA 2 Summary 1 As a basis for pre-acquisition planning synthetic seismograms of an onshore 3D seismic-whiledrilling (SWD) experiment have been computed. The main objective was to optimise the acquisition parameters and the geometrical configuration of the deployed seismic lines prior to the in-situ measurements. Geological and geophysical (seismic and borehole) data were used to obtain the 3D geological model around the well. The synthetic seismograms were obtained with a 3-D elastic forward modelling code based on
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Full Waveform Inversion Using the Nonmonotone Spectral Projected Gradient Method
Authors N. Zeev, O. Savasta and D. CoresP011 FULL WAVEFORM INVERSION USING THE NONMONOTONE SPECTRAL PROJECTED GRADIENT METHOD NOAM ZEEV 1 OLGA SAVASTA 2 and DEBORA CORES 1 1 1 Universidad Simón Bolívar 2 PDVSA-Intevep Apdo. 76343 Caracas 1070-A Venezuela SUMMARY The Seismic Inversion problem is a large-scale optimization problem that has been solved using different optimization strategies that usually converge locally and get stuck in a secondary minimum. Since it is a large-scale problem computational efficient and low time consuming optimization techniques are also convenient. We proposed to solve the full waveform inversion using the nonmonotone spectral projected gradient method. The new methodology allows the objective
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SWD Tomography by Radial Staggered Grids at a Geothermal Well
Authors A.L. Vesnaver, F. Accaino, F. Batini, P. Corubolo, L. Petronio and G. RossiP-12 SWD TOMOGRAPHY BY RADIAL STAGGERED . GRIDS AT A GEOTHERMAL WELL . Abstract F. ACCAINO 1 F. BATINI 2 P. CORUBOLO 1 L. PETRONIO 1 G. ROSSI 1 and A. VESNAVER 1 1 OGS Borgo Grotta Gigante 42/c 34010 Trieste Italy 2 ERGA – Gruppo Enel Via A. Pisano 120 56122 Pisa Italy Drill-bit Seismic-While-Drilling is the only possible seismic survey for geothermal wells at extreme pressure and temperature conditions. As for oil and gas production the knowledge of the rock lithology around the well is a key for the exploitation planning and 3D tomography is a valuable tool
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Ray Tomography on Creeping-Waves
Authors A. Krauklis, A. Malik and V. TroyanP013 DIRECT AND INVERSE PROBLEMS OF RAY TOMOGRAPHY ON THE CREEPING WAVES Ray tomography widely applied in the global seismology exploration geophysics and seismic engineering usually uses body waves. The surface waves are employed rarely partly because of their more complicated cinematical and dynamical properties. However it is possible to point out the problems which effective solution could be gained only by the surface waves ray tomography. In the paper we consider by means of the numerical modeling the travel time inversion of the creeping spiral waves. This waves are able to transit along the curved interface for a long
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Frequency Domain Waveform Inversion - A Strategy for Choosing Frequencies
Authors L. Sirgue and R.G. PrattP014 Frequency Domain Waveform Inversion: A strategy for choosing frequencies. Summary 1 We present a methodology defining an optimal temporal frequency sequence in the reconstruction of velocity perturbations from a surface seismic survey. We show that in the case of a 1-D perturbation of an otherwise homogeneous medium this sequence depends only on the depth of the perturbation and on the offset range present in the acquisition. The main idea derived from diffraction tomography is that the larger the offset range the fewer frequencies are needed. We use this approach to find a set of temporal frequencies that provides a
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Exploration of Igneous Cored Domes, Taranaki Basin, New Zealand
Authors B. Leitner, A. Hart and G. ThrasherP021 EXPLORATION OF IGNEOUS CORED DOMES TARANAKI BASIN NEW ZEALAND Abstract: Although known to host hydrocarbons the Neogene igneous cored domes of the North Taranaki Basin are an under-explored play. Exploration of these features requires developing geophysical methods for imaging them and geological models for predicting reservoir quality. Research on two of the domes Kora and Nga Motu leads to new concepts for their exploration. 1 Introduction: Taranaki Basin provides New Zealand’s petroleum production from a number of oil and gas fields. The smallest and oldest (since 1865) is the Moturoa Field where oil is produced from Neogene turbidites proximal
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Thrust Belt Exploration by "Global Offset" Seismic and Reflection/Refraction Tomography
Authors P. Dell‘Aversana, D. Colombo, S. Morandi and M. BuiaP022 THRUST BELT EXPLORATION BY “GLOBAL OFFSET” SEISMIC AND REFLECTION/REFRACTION TOMOGRAPHY Abstract 1 Between September and November 1999 two test seismic lines were recorded in the Southern Apennine region (S. Italy) using the “Global Offset” technique (Dell’Aversana et al. 1999 Dell’Aversana et al. 2000). This experimental acquisition project was carried out as part of the ESIT research project (Enhance Seismic In Thrust belt) funded by the European Union Enterprise Oil and Eni-Agip. An iterative and interactive tomographic inversion of refraction/reflection arrivals was carried out on the recorded data of one of the lines (ESIT700) to produce a velocity/interface model in
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Deep Structure Model of the Sedimentary Basins in the West Pacific
More LessP023 DEEP STRUCTURE MODEL OF THE SEDIMENTARY BASINS IN THE WEST PACIFIC 1 A.G. RODNIKOV Geophysical Center Russian Academy of Sciences Molodezhnaya 3 GSP-1 117296 Moscow Russia Introduction The study of the deep structure of sedimentary basins of marginal seas in the Transition Zone from the Eurasian Continent to the Pacific Ocean was carried out in the frame of the International Geotraverse Project on deep cross-sections of the lithosphere including asthenosphere. The cross-sections are: the Okhotsk Sea Geotraverse; the Japan Sea Geotraverse and the Philippine Sea Geotraverse (Rodnikov 2000). General characteristics of deep structure of sedimentary basins are the following:
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Baikal Rift Zone Investigation by Modern Gravity Data
Authors A.A. Tchernov and A.S. BaluevP024 BAIKAL RIFT ZONE INVESTIGATION BY MODERN GRAVITY DATA A.TCHERNOV 1 and A. BALUEV 2 1 1 VNIIGeofizika 2/4 Krasnoproletarskaya str. 103006 Moscow Russia 2 Institute of litology RAN SUMMARY Baikal rift is one of most interesting but at the same time of least investigated zones of Globe. The real opportunities of detailed study of the Baikal depression have appeared after realization precision of gravimetrics observations of scale 1:200 000 and seismic profile shooting on water area of lake. The faults complicating an internal geological structure Baikal grabene connection of such faults with a disjunction network of an environmental land
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Deep Structure of the Barents Plate from Geophysical Investigations
Authors N.M Ivanova, J.I. Matveev, T.S. Sakoulina and M.L. VerbaP025 DEEP STRUCTURE OF THE BARENTS PLATE FROM GEOPHYSICAL INVESTIGATIONS SUMMARY 1 The Barents Plate (BP) is the largest shelf structure of the Arctic region passed starting up Pre- Cambrian through paraplatform platform rift and basin phase of tectonic evolution. As a result a sedimentary cover was formed the total thickness of one reaches to 20 km. Three large tectonosedimentary complexes are distinguished in the sedimentary cover. They are: a lower terrigenouscarbonate complex of Paleozoic a middle mainly carbonate complex of Upper-Devoninan-Permian and an upper terrigenous complex of Permian-Cenozoic age. The BP has mainly continental type of Earth crust although
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Interpretation of Geophysical Data in the SW Sardinian Shelf, Western Mediterranean
Authors S. Fais, E.E. Klingele and L. LeccaP026 INTERPRETATION OF GEOPHYSICAL DATA IN THE SW SARDINIAN SHELF (WESTERN MEDITERRANEAN) S. FAIS 1 E.E. KLINGELE 2 and L. LECCA 3 Abstract 1 An improved tectonic model of the southwestern continental margin of Sardinia from an integrated interpretation of high resolution reflection seismic data and aeromagnetic data is presented in this paper. The investigated area located over a submerged crustal block was affected by extensional tectonics correlable with the extensional phase that characterized the well-known Oligo-Miocene opening of the Western Mediterranean. By the analysis of the Sparker high-resolution seismic data it was possible to recognise the main structural features
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Structure of Crust of Kuril-Kamchatka Region from 2D Interpretation of Refraction Data
Authors V.B. Piip and A.L. VolokhP027 STRUCTURE OF CRUST OF KURIL- KAMCHATKA REGION FROM 2-D INTERPRETATION OF REFRACTION DATA Abstract 1 Structures of the crust including zones subduction and rift zone were obtained from the reinterpretation of refraction data of past years in the region of Kuril trench and Sea of Okhotsk. Numerous faults and thrust break the subducting slab in the Kuril trench. Complex and deformed blocks of oceanic crust and upper mantle form the hanging wing of subduction zone. In the central part of the Sea of Okhotsk the structure of relic subduction zone is obtained. The rift or spreading structure is present
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Location of the Precambrian Plate Boundary in the NW USA from Gravity and Magnetic Data
By K.L. MickusP028 LOCATION OF THE PRCAMBRIAN PLATE BOUNDARY IN THE NW USA FROM GRAVITY AND MAGNETIC DATA KEVIN MICKUS SW Missouri State University Department of Geosciences 65807 Springfield USA 1 SUMMARY Gravity and aeromagnetic data are used to map the location of the Precambrian continental margin in the northwestern United States plus determine tectonic features beneath the Columbia River Plateau basalts (CRPB). The Precambrian boundary may follow a sharp northwest-trending magnetic gradient that also marks the boundary of several residual gravity maxima. The Proterozoic Belt Basin is distinguished by a regional gravity minimum that extends to 118 o W beneath the
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Forward Modelling for Electro-Kinetic Effects
Authors A. Ranada Shaw, D. Van der Burg, A.I.M. Denneman and C.P.A. WapenaarP031 FORWARD MODELLING FOR ELECTRO-KINETIC EFFECTS ANTONIO RANADA SHAW DENNIS VAN DER BURG ARTHUR DENNEMAN and KEES WAPENAAR Section of Applied Geophysics Centre for Technical Geoscience Delft University of Technology The Netherlands Introduction The electrokinetic effect represents a group of processes in which there is a conversion from electromagnetic to kinetic energy and vice versa. In the case of this transfer taking place in a porous medium we name the effects electro-osmotic for the transfer from electromagnetic to kinetic energy and seismo-electric for the transfer from kinetic to electromagnetic energy. There exist other effects also called electro-kinetic like the piezo-electric
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Petrophysical Studies of Sandstones under True-Triaxial Stress Conditions
Authors M.S. King, X.D. Jing and J.R. MarsdenP032 PETROPHYSICAL STUDIES OF SANDSTONES UNDER TRUE-TRIAXIAL STRESS CONDITIONS 1 An innovative polyaxial (true-triaxial) stress-loading system has been developed (King et al. 1995) for conducting petrophysical tests on 50mm-side cubic specimens of rock with the capability of varying two of the principal stresses independently to 115MPa and the third to 750Mpa (Figure 1) with pore pressures limited to 5MPa. It was originally designed to study all nine components (3 P and 6 polarized S) of ultrasonic velocities and attenuation (Figure 2) and directional fluid permeability in the three principal stress directions as oriented sets of fractures were induced in the
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Sensitivity of Interfacial Compliances to Fluid Saturation and Pore Pressure
More LessP033 SENSITIVITY OF INTERFACIAL COMPLIANCES TO FLUID SATURATION AND PORE PRESSURE ENRU LIU 1 XIANG-YANG LI 1 and ZHONGJIE ZHANG 2 Introduction 1 Dynamic monitoring of fluid movement in reservoirs using time-lapse seismic has become increasingly popular in hydrocarbon industry. On the other hand in deepwater environment wells are expensive and the increased costs associated with drilling in overpressured formation demands a reliable prediction of pore pressure (Sayers et al. 2000). Therefore the need to quantitatively characterise the seismic signature of fluid saturation and pore pressure is becoming more important than ever before. In this study we shall investigate the
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Acoustic Arrays in Rock Physics
Authors N. Al-Jabari, D. Bowen, D.P. Hand, J.D.C. Jones, W.N. MacPherson, W.S.O. Rodden and A.R. WestermanP034 ACOUSTIC ARRAYS IN ROCK PHYSICS Abstract Most acoustic measurements made in Rock Physics laboratories are taken over the length of a cylindrical core specimen. Figure 1a b shows how three traces are usually recorded: - A single P-wave trace - Two orthogonally polarized S-wave traces. 1 N. AL-JABARI 1 D. BOWEN 1 D.P. HAND 2 J.D.C. JONES 2 W.N. MACPHERSON 2 W.S.O. RODDEN 2 and A.R. WESTERMAN 1 1 Heriot-Watt University Department of Petroleum Engineering Riccarton Edinburgh EH14 4AS UK 2 Heriot-Watt University Physics Department Figure 1: a) normal core acoustic measurements b) P and S waveforms in Rock
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Low Frequency Acoustic Characterisation of Unconsolidated Synthetic Sediment Samples
Authors A.S. Lucas, C. McCann and J. SothcottP035 LOW FREQUENCY ACOUSTIC CHARACTERISATION OF UNCONSOLIDATED SYNTHETIC SEDIMENT SAMPLES Introduction 1 Unconsolidated gravel deposits are frequently encountered in the context of high-resolution CHIRP and boomer seismic surveys of marine continental shelves for submarine engineering and exploration purposes. The acoustic and geotechnical properties of such sediments however are poorly understood resulting in imaging and interpretation problems with the resultant seismic data. Hence there is a need to investigate the acoustic properties of clastic and biogenic gravel deposits typically encountered on the seafloor and immediate subsurface (sub-bottom) of continental shelves at sonic frequencies similar to those used in marine surveying and
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Acoustic Frequency Signatures of Laboratory Fractured Rocks
Authors A. Rozanov, A. Zang, C. Wagner and G. DresenP036 ACOUSTIC FREQUENCY SIGNATURES OF LABORATORY FRACTURED ROCKS 1 Introduction. Laboratory acoustic emission (AE) studies are useful as scale models of earthquakes and mining rock bursts. This study is focused on the frequency content of AE signals and ultrasonic transmission signals detected from rock triaxially stressed to fracture. Specifically we investigate AE source (crack) parameters using a spectrum analysis of AE signals. Experimental Technique. We performed triaxial compression tests on rock cores (diameter 50 mm length 100 mm) with symmetric and asymmetric top loading (Fig.1). The asymmetric loading test is used to fix the nucleation patch from which a shear
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The Acoustic Properties of Carbonates at Sonic and Ultrasonic Frequencies
Authors J. Sothcott, S. Assefa, C. McCann and S.E. JohnstadP037 THE ACOUSTIC PROPERTIES OF CARBONATES AT SONIC AND ULTRASONIC FREQUENCIES J.SOTHCOTT 1 S.ASSEFA 1 C.M C CANN 1 and S.E. JOHNSTAD 2 Summary This abstract describes a set of acoustic velocity and attenuation measurements on two fully brine saturated carbonates at low and high frequencies. The data demonstrate that at reservoir pressures the compressional wave and shear wave quality factors increase (attenuation decreases) with decreasing frequency and that the velocity dispersions are significantly smaller than those of reservoir sandstones. Aim 1 The aim of this work is to investigate the effect of frequency scaling on the acoustic properties of
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Effective Velocities in Fractured Media - Intersecting and Parallel Cracks
Authors E.H. Saenger and S.A. ShapiroP038 Effective velocities in fractured media: Intersecting and parallel cracks 1 Summary 1 This paper is concerned with a numerical study of effective velocities in two types of fractured media. We apply the so-called rotated staggered finite difference grid technique. Using this modified grid it is possible to simulate the propagation of elastic waves in a 2D or 3D medium containing cracks pores or free surfaces without hard-coded boundary conditions. Therefore it allows an efficient and precise numerical study of effective velocities in fractured structures. We model the propagation of plane waves through a set of different randomly cracked media.
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Seismic Anisotropy in Sediments with Clay-Sand Mixture
More LessP- 039 SEISMIC ANISOTROPY IN SEDIMENTS WITH CLAY-SAND MIXTURE Introduction Yan Jun 1� 2 Enru Liu 1 and Xiang-Yang Li 1 1 British Geological Survey Murchison House West Mains Road Edinburgh EH9 3LA UK 2 Department of Geology and Geophysics University of Edinburgh UK One of the most important factors a ecting seismic velocities in anisotropic formation is the presence of aligned pores clay particles and/or cracks. Extensive theoretical work and laboratory experiments have been devoted to this subject. One of the very successful models has been developed by Xu and White (1995) to model clay-sand mixture and this model
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Physical Properties of Rocks as Multiple Parameters for Lithology Discrimination
More LessP040 PHYSICAL PROPERTIES OF ROCKS AS MULTIPLE PARAMETERS FOR LITHOLOGY DISCRIMINATION M. BOSCH 1 M. ZAMORA 2 and W. UTAMA 2 Abstract 1 We performed a series of test on discrimination of rock sample lithology based on the knowledge of several physical properties of the samples which were measured under laboratory conditions. The lithology corresponded to common rock types and the discriminative parameters were physical media properties: density compressional velocity shear velocity thermal conductivity and electric conductivity. We did not include parameters involving rock composition or rock texture for the discrimination. The objective of the work is to show the
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Wave Velocities Amplitude Dependence and Hysteresis in Consolidated Rocks under Confining Pressure
Authors A.A. Boulytchov, E.I. Mashinskii, V.Z. Koksharov and B.A. BobrovP041 WAVE VELOCITIES AMPLITUDE DEPENDENCE AND HYSTERESIS IN CONSOLIDATED ROCKS UNDER CONFINING PRESSURE Abstract 1 The laboratory experiments on duraluminium quartz sandstone under confining pressure (up to 40 MPa) have shown a nonlinear dependence of wave velocities Vp and Vs on amplitude and their hysteresis. In a range of strain amplitudes 10 -7 -10 -6 modifications of waves velocities achieve 0 84 %. The possible reason of non-linearity is the micro-plasticity. Introduction Linearly elastic model of a geological medium used in seismics not adequately describes a real situation of seismic wave propagation. Linearly inelastic model has the best approximation but
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SP Implementation in Deep-Sea Sulphides Searches
By A.A. PetrovP045 SP IMPLEMENTATION IN DEEP-SEA SULPHIDES SEARCHES ALEXANDER A. PETROV Sevmorgeo State Company Rozenshteina Street 36 198095 St. Petersburg Russia Summary 1 The solution of a direct task for a spontaneous electrical field of deep-sea hydrothermal sulphide deposits is considered. The results of modeling demonstrate the opportunities of targets detection by any field components measurement. Two approaches to the decision of a reverse task are offered. In the first case the measured fields are approximated by set of fields of a small number of separate local objects. In the second variant the cell parameters of a regular mesh covering all
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2D Resistivity Imaging Technique - an Alternative Solution for Boring Problems in Boulders Prone Areas
Authors Z.Z.T. Harith, M.N.M. Nawawi and A.M. AzizP046 2D RESISTIVITY IMAGING TECHNIQUE – AN ALTERNATIVE SOLUTION FOR BORING PROBLEMS IN BOULDERS PRONE AREAS 1 Z.Z.T. HARITH 1 M.N.M. NAWAWI 1 and A.M. AZIZ 2 1 School of Physics University Science Of Malaysia 11700 Pulau Pinang Malaysia 2 Road Design Unit Public Work Department Kuala Kumpur Malaysia Introduction In most of the civil engineering projects accurate information on the physical properties of underlying material be it soils or rocks is needed before designing any structure or constructing any buildings. The accurate information on the physical properties can be obtained through several investigation programs. The main purpose of the
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Extending the Limits of Resistivity Modelling Using Multigrid Techniques
Authors R. Moucha and R.C. BaileyP047 EXTENDING THE LIMITS OF RESISTIVITY MODELLING USING MULTIGRID TECHNIQUES Abstract 1 We present an adaptation of the multigrid algorithm application to the solution of the DC resistivity modelling problem in geophysics. Previous work on multigrid solvers in this application (e.g. Cheesman and Bailey 1996) has shown that multigrid is fast but probably not significantly faster than other good solvers that have been implemented such as biconjugate gradient (Mackie et. al. 1995). The potential importance of multigrid solvers does not however lie in their speed at forward modelling but in their potential for inverse modelling. Inverse solvers which proceed by
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