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64th EAGE Conference & Exhibition
- Conference date: 27 May 2002 - 30 May 2002
- Location: Florence, Italy
- Published: 27 May 2002
1 - 100 of 688 results
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A Comparison of High Density Velocity Fields Obtained from Isotropic and Anisotropic PSDM as a Constraint on Amplitude Inversion
Authors A. Ratcliffe, G. Williams and K. HawkinsAnisotropic prestack depth migration (PSDM) has clear benefits for imaging purposes in
many areas. An additional benefit of the anisotropic imaging is that the velocity field derived
for migration ties closely to vertical well velocities. It is therefore possible that this velocity
field contains more accurate information than an isotropically derived field and, consequently,
gives better constraints on amplitude inversion of the seismic data.
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Mid-Shelf Lowstand and Transgressive Systems Tract Deposits of Southeast Asia - Examples from Offshore Java and Malaysia
More Less1001 MID-SHELF LOWSTAND AND TRANSGRESSIVE SYSTEMS TRACT DEPOSITS OF SOUTHEAST ASIA - EXAMPLES FROM OFFSHORE JAVA AND MALAYSIA 1 Lowstand and transgressive systems tract deposits on the northwest Java shelf are documented based on an integrated analysis of 3D seismic shalllow-penetration seismic data well-log and conventional core data. These data show that incised valley systems formed during sea-level lowstand extend in excess of 200-500 km inboard of the shelf margin. They range from 2-5 km wide and up to 40 m deep. These incised valleys seem to have formed during only the lowest of lowstand times during relatively short intervals.
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Deltaic Sandbody Connectivity - Sequence Stratigraphic-based Insights from 3-D Reservoir Modeling Studies, Sunrise-Troubadour Fields, Australia
More Less1002 DELTAIC SANDBODY CONNECTIVITY - SEQUENCE STRATIGRAPHIC-BASED INSIGHTS FROM 3-D RESERVOIR MODELING STUDIES SUNRISE-TROUBADOUR FIELDS AUSTRALIA 1 The Sunrise-Troubadour Fields represent a 16.7 Tcf gas-condensate resource located in the Timor Sea 450 km to the northwest of Darwin Australia. The Middle Jurassic reservoir succession is relatively thin (80 m) but laterally extensive with a combined area of closure of over 1000 square kilometers. One of the major subsurface uncertainties in the evaluation of these fields is reservoir connectivity due to sandbody geometry and post-depositional faulting. This study addresses these connectivity uncertainties via a sequence stratigraphic-based 3-D reservoir modeling approach. The
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Paleocene Deep-Water Depositional Systems along the Eastern Margin of the Frontier Møre and Vøring Basins, Mid-Norway
Authors O.J. Martinsen and J. Gjelberg1003 PALEOCENE DEEP-WATER DEPOSITIONAL SYSTEMS ALONG THE EASTERN MARGIN OF THE FRONTIER MØRE AND VØRING BASINS MID-NORWAY Paleocene deep-water depositional systems along the eastern margin of the Møre and Vøring Basins offshore Mid-Norway are proven and potential reservoir-bearing units within the Cenozoic stratigraphic succession. The recent gas discovery in the giant Ormen Lange field shows the petroleum potential of the region related to the deposition of turbidites in submarine fans. 1 OLE J. MARTINSEN and JOHN GJELBERG Norsk Hydro Research Center ASA PO Box 7190 Bergen 5020 Norway The distribution of confirmed Paleocene sandstones offshore Mid-Norway was profoundly controlled by
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Frontier Exploration on the Abyssal Plain of the Deepwater Gulf of Mexico - Syn-Rift through Passive Stage Mesozoic Objectives Identified
Authors M.J. Roberts and S.G. Reilly1004 FRONTIER EXPLORATION ON THE ABYSSAL PLAIN OF THE DEEPWATER GULF OF MEXICO - SYN-RIFT THROUGH PASSIVE STAGE MESOZOIC OBJECTIVES IDENTIFIED 1 MICHAEL J. ROBERTS and SEAMUS G. REILLY Chevron North America Exploration and Production Co 935 Gravier Street New Orleans LA 70112 USA The abyssal plain of the Gulf Of Mexico (GOM) defined here as areas basinward of the Mississippi Fan and Perdido Foldbelts has been described as a featureless plain devoid of significant structuring and underlain by oceanic crust. A regional examination of the province cast doubt on this benign history and revealed a complex structural province with
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An Experimental Study of the Effect of Subsidence and Water Supply on Fluvial Architecture
Authors N. Strong, B.A. Sheets, T.A. Hickson and C. Paola1005 AN EXPERIMENTAL STUDY OF THE EFFECT OF SUBSIDENCE AND WATER SUPPLY ON FLUVIAL ARCHITECTURE 1 NIKKI STRONG 1 BENJAMIN A. SHEETS 1 THOMAS A. HICKSON 2 and CHRIS PAOLA 3 1 St Anthony Falls Laboratory University of Minnesota Minneapolis MN 55414 USA 2 St. Anthony Falls Laboratory University of Minnesota 3 Department of Geology & Geophysics University of Minnesota The Experimental EarthscapeFacility (XES) at St. Anthony Falls Laboratory of the University of Minnesota is a 6 meter by 13 meter by 1.3 meter deep basin with a programmable subsiding floor. We used this system to model a braided fluvial-deltaic
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50 Years Hence – Evolving Technologies and Opportunities in Carbonate Systems
By C. Kerans1006 50 YEARS HENCE - EVOLVING TECHNOLOGIES AND OPPORTUNITIES IN CARBONATE SYSTEMS 1 Carbonate reservoirs are famous for their prolific reserves and infamous for their complexity and unpredictable behavior. Yet it is precisely this combination of vast promise and challenging technical frontiers that ensures that carbonate hydrocarbon reservoirs will form the cornerstone of global energy supply for the next half-century. The vast resource still remaining in giant carbonate oil fields in the Middle East the Caspian region the Cretaceous of Latin America the Atlantic and Caribbean provides substantial motivation for a renewed focused R&D effort in carbonate exploration and exploitation
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The Distinction between Ancient Fluvial and Valley-Fill Sandstone Reservoirs: Semantics or Economics
By M.H. Gardner1007 THE DISTINCTION BETWEEN ANCIENT FLUVIAL AND VALLEY-FILL SANDSTONE RESERVOIRS - SEMANTICS OR ECONOMICS 1 Because fluvial sandstones form significant reservoirs a mature set of geologic models exists that relates facies sediment bodies and geomorphology to reservoir heterogeneity. Most subsurface channelform sandbodies were interpreted as channels when fluvial models were first developed (60s and 70s). Sequence stratigraphy (80s and 90s) reinterpreted many of these as incised valley-fills. Today valley fills represent the favored interpretation for subsurface channelforms. Has the pendulum swung too far? A matter of semantics or are their economic implications to these terms? The Ferron Sandstone was deposited
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A Strategy for Automatically Modelling Extensional Sedimentary Basins
Authors N.J. White, D. Hanne and P. Bellingham1008 A STRATEGY FOR AUTOMATICALLY MODELLING EXTENSIONAL SEDIMENTARY BASINS 1 NICHOLAS J WHITE 1 DETLEF HANNE 1 and PAUL BELLINGHAM 2 1 Earth Sciences University of Cambridge Bullard Laboratories Madingley Rise Madingley Road Cambridge CB3 0EZ UK A two-dimensional inverse model for extracting the spatial and temporal variation of strain rate from extensional sedimentary basins is described. Our starting point is a forward model which allows basin stratigraphy to be calculated from any given strain rate distribution. This forward model includes potentially important effects such as flexural rigidity and the twodimensional conduction/advection of heat. Conversely inverse modelling determines strain rate
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Seismic Geomorphology and Depositional Systems of Deep Water Environments; Observations from Offshore Nigeria, Gulf of Mexico, and Indonesia
More Less1009 SEISMIC GEOMORPHOLOGY AND DEPOSITIONAL SYSTEMS OF DEEP WATER ENVIRONMENTS; OBSERVATIONS FROM OFFSHORE NIGERIA GULF OF MEXICO AND INDONESIA 1 Four principal depositional elements are recognized in deep-water depositional environments offshore Nigeria Gulf of Mexico and Indonesia. These include channels levees frontal splays and debris flow deposits. Individual channels range from moderate to high sinuosity and are up to 2-3 km wide. Channel fills can be single-stage or multi-stage fill. In the latter channel type leveed channel complexes are said to exist. In many instances channel meander evolution is characterized by aggradation and down-system meander loop migration. The result of
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Improved Seismic Resolution through Fine Spatial Sampling - a 2D Example, Onshore Abu Dhabi
Authors J. Quigley, I. Haggag, A.B. Al Jeelani and E. KleissA-01 IMPROVED SEISMIC RESOLUTION THROUGH FINE SPATIAL SAMPLING - A 2D EXAMPLE ONSHORE ABU DHABI Abstract 1 During the late 1990's efforts were made by the Abu Dhabi Company for Onshore Operations (ADCO) in co-operation with WesternGeco to improve 3D seismic data quality by redistributing the source point energy over a finer spatial sampling of source points in the cross line direction. With the success of this approach and better understanding of the source-related issues consideration was given to optimization of the 3D receiver configuration. The receiver array pattern used for 3D surveys had been derived from earlier empirical 2D
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Surface Marine All Azimuth Recording Technique
Authors J. Paffenholz, J. Keliher, R. Ergas and B. McLainA-02 SURFACE MARINE ALL AZIMUTH RECORDING TECHNIQUE Summary 1 The SMAART JV 1 created a 3D earth model to investigated target illumination representative of sub-salt plays in the Gulf of Mexico. Ray tracing on this model reveals that conventional towed streamer acquisition would leave a substantial illumination hole at the target horizon. No one streamer orientation is sufficient to illuminate this area. However the width of the illumination hole was substantially reduced if all-azimuth areal shot record geometries such as Vertical Cable or OBC were used. We present a novel multi-azimuth acquisition method capable of reducing the illumination hole below
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Six-Fold Simultaneous Vibratory Recording Experiment
Authors T. Bianchi, L. Cherel, B. Pagliccia and J. MeunierA-03 SIX-FOLD SIMULTANEOUS VIBRATORY RECORDING EXPERIMENT Abstract 1 In order to reduce the size of the source array and ultimately achieve point source in Vibroseis™ acquisition without degrading signal to noise ratio or increasing costs high-fold simultaneous acquisition must be used. Several techniques are already known but not commonly used. An experiment of multi-source acquisition was conducted in Argentina to compare different techniques. Introduction Reducing the size of the source array leads to a reduction in the energy of the source. The implications of this reduction on the signal-to-noise ratio can be evaluated using the square root theory. A widely
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A Universal Simultaneous Shooting Technique
Authors R.J. de Kok and D. GillespieA-04 A UNIVERSAL SIMULTANEOUS SHOOTING TECHNIQUE ROB DE KOK and DIANA GILLESPIE 1 Summary A novel method for the simultaneous recording of seismic data from two or more sources is presented. The coding for the different sources consists of the introduction of either polarity or time delay changes in the field. Separation is achieved through polarity decoding followed by averaging and/or interpolation during processing. For purposes of averaging not only dedicated techniques but also standard processes such as stacking and migration can be relied on. The method is applicable to all possible types of sources and has no restriction as
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Low Frequency Sub-Basalt Imaging
Authors A.M. Ziolkowski, P. Hanssen, R.W. Gatliff, X.-Y. Li, H. Jakubowicz and H. HampsonA-05 LOW FREQUENCY SUB-BASALT IMAGING Summary 1 Ocean margin basalts are extremely heterogeneous and scatter the seismic energy of the conventional seismic reflection system. To observe sub-basalt reflections the system should be modified to emphasize the low frequencies using much larger air guns and towing the source and receivers at about 20 m depth. The rationale for this approach is supported by synthetic seismograms over a realistic 1-D earth model. In the summer of 2001 we obtained data over basalt in the North-East Atlantic using a system modified to incorporate these ideas. Introduction ANTON ZIOLKOWSKI 1 PETER HANSSEN 2 ROBERT
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A Novel Compensation Method for the Source Directivity of an Air-Gun Array
Authors S.W. MacKay, J. Douma and E.C. MobleyA-06 A NOVEL COMPENSATION METHOD FOR THE SOURCE DIRECTIVITY OF AN AIR-GUN ARRAY 1 JAN DOUMA and EVERETT C. MOBLEY WesternGeco 10001 Richmond Avenue Houston TX 77042 USA Abstract The far-field signatures for angles-of-incidence ranging from zero to fifty degrees have been analyzed for various air-gun arrays. These analyses demonstrate that due to the directivity of the air-gun arrays the difference between an individual signature and the average signature is 8 to 10 dB lower than the average signature. This differential energy is a consequence of amplitude and phase differences between the signatures for the various take-off angles. This differential
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Sea Surface Shape Derivation above the Seismic Streamer
More LessA-07 SEA SURFACE SHAPE DERIVATION ABOVE THE SEISMIC STREAMER E. KRAGH 1 R. LAWS 1 and L. COMBEE 2 1 1 Schlumberger Cambridge Research High Cross Madingley Road Cambridge CB3 OEL UK Summary: In this paper we show a method of deriving the shape of the time-variant sea surface above the seismic streamer. We record very low-frequency single-sensor data below 0.5 Hz using seismic hydrophones. We then invert the resulting pressure variations to give the wave heights and streamer displacement as functions of position and time. The concurrent recording of the conventional seismic data is unaffected by this method. The
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PZ Calibration Using Critically Refracted Waves
Authors A. Strømmen Melbø, J.O.A. Robertsson and D.-J. Van ManenA-08 PZ CALIBRATION USING CRITICALLY REFRACTED WAVES Abstract In marine multi-component seismic data the vertical geophone recordings must be calibrated against the pressure recordings to account for differences such as coupling and impulse responses of the measuring devices. One known way of doing this is by applying the equation of motion and minimizing the downgoing energy in a window containing only primary reflections (Schalkwijk et al. 1999). Picking such a window may be difficult if we have a long source signature or when operating in shallow water. In this paper we utilize the same calibration approach based on a window
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Imaging through Gas Clouds - a Case History from the Gulf of Mexico
More LessA-09 IMAGING THROUGH GAS CLOUDS - A CASE HISTORY FROM THE GULF OF MEXICO 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 to be obtained that are unobstructed by the gas and/or fluids. This reduces the risk
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MEMS for Geophysicists
Authors J. Tessman, B. Reichert, J. Marsh, J. Gannon and H. GoldbergA-10 MEMS FOR GEOPHYSICISTS 1 JON TESSMAN BRUCE REICHERT JIM MARSH JEFF GANNON and HOWARD GOLDBERG Summary Input/Output Inc. has developed a MEMS accelerometer to use as a seismic sensor for oil and gas exploration. Currently moving coil inductive geophones are used as seismic sensors. Geophone design and performance have evolved for more than 50 years to the point that modern geophones are small rugged highly sensitive to motion and produce minimal background noise. Achieving performance superior to a modern geophone with a MEMS accelerometer has been a significant technical challenge but other benefits enabled by MEMS and accelerometer technology
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Can Joint PP and PS Velocity Analysis Manage to Corner d, the Anisotropic Depthing Parameter?
Authors F.S. Audebert, P.Y. Granger, C. Gerea and A. HerrenschmidtA-11 CAN JOINT PP AND PS VELOCITY ANALYSIS MANAGE TO CORNER δ THE ANISOTROPIC DEPTHING PARAMETER ? Introduction 1 FRANÇOIS AUDEBERT 1 PIERRE-YVES GRANGER 1 CONSTANTIN GEREA 2 The depthing or tying of seismic images to the well has been a perennial and frustrated demand made by the geologist. Anisotropy usually got the blame. Though nowadays we have at hand the theoretical understanding and tools to extract velocity anisotropy information from surface seismic there is still doubt about the sensitivity of surface seismic upon the parameter δ responsible for depthing as described by Thomsen (1986). Maybe the PS converted waves
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An Inverse-Scattering Sub-Series for Predicting the Spatial Location of Reflectors without the Precise Reference Medium and Wave Velocity
Authors S.A. Shaw, A.B. Weglein, D.J. Foster, K.H. Matson, P.M. Carvalho and D. CorriganA-13 AN INVERSE-SCATTERING SUB-SERIES FOR PREDICTING THE SPATIAL LOCATION OF REFLECTORS WITHOUT THE PRECISE REFERENCE MEDIUM AND WAVE VELOCITY Summary 1 The accurate location resolution and identification of targets beneath complex media (e.g. salt basalt and karsted sediments) are high priority and essentially unsolved problems today. Imaging methods that are tested and compared using synthetic data with precise model velocity as input are not addressing the real-world problem. At the very least imaging methods need to be tested using synthetic data and a velocity model that corresponds to what would be estimated from the data using current best velocity analysis
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Three-Dimensional Prestack Inversion, Lobo Trend, South Texas
Authors P. Anno, M. Wuenscher, R. Corbin, J. Hooper and F. ChlumskyA-14 THREE-DIMENSIONAL PRESTACK INVERSION LOBO TREND SOUTH TEXAS Summary 1 We demonstrate the difficulty with mapping a Lobo (Paleocene) hydrocarbon reservoir directly from stacked seismic data. A strong response in the stacked volume is ambiguous indicating either a large impedance contrast or a contrast in Poisson’s ratio. That is stacking of reflection amplitudes over offset (or reflection angle) incorporates reflections from impedance perturbations with those due to a change in Poisson’s ratio. Dipole sonic log data indicate Poisson’s ratio but not impedance distinguishes this particular Lobo reservoir from shale. The hydrocarbon reservoir impedance is similar to that of encasing shales.
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Seismic Repeatability, Normalised RMS and Predictability
Authors E. Kragh and P. ChristieA-15 SEISMIC REPEATABILITY NORMALISED RMS AND PREDICTABILITY ED KRAGH and PHIL CHRISTIE 1 Summary: Time-lapse seismic requires quantifiably repeatable data. In this paper we present a repeated 2D seismic line and show that the repeatability is correlated with streamer position differences. We examine repeatability in terms of the normalized RMS difference and the predictability (normalized cross power or coherence). An inverse relationship exists between the two metrics and while neither metric is an intuitive measure of repeatability their combination offers a possible methodology for matching datasets. Introduction: Time-lapse data are increasingly used to study production-induced changes in the seismic response
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4D Acquisition Geometry Requirements and QA
Authors R.W. Calvert, P. Hatchell and C. JonesA-17 4D ACQUISITION GEOMETRY REQUIREMENTS AND QA Summary. 1 RODNEY CALVERT PAUL HATCHELL and CHARLES JONES Shell International Exploration and Production B.V PO Box 60 2244 AB Rijswijk The Netherlands 4D seismic monitoring surveys aim to determine production effects by comparing 2 or more repeat surveys. These comparisons often indicate false changes due to production where non exist. These false indications are caused by system “Non-Repeatability” and represent a limitation to the 4D method. In many places the most serious form of non-repeatability occurs when acquisition source and receiver locations are not repeated. This paper describes a practical method for
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Time-Lapse Filtering and Improved Repeatability with Automatic Factorial Co-Kriging, AFACK
By T. ColeouA-18 TIME-LAPSE FILTERING AND IMPROVED REPEATABILITY WITH AUTOMATIC FACTORIAL CO-KRIGING (AFACK) T. COLEOU Summary 1 Acquisition and processing imprints are considered negligible with standard 3D processing but become critical when computing time-lapse seismic differences. A new technique AFACK particularly effective for equalising surveys and removing unwanted imprints is presented here. It uses an automated version of a geostatistical technique called Factorial Co-Kriging. Variograms and cross-variograms also provide a measure of the spatial cross variability that lead to a good indicator of spatial repeatability. Introduction CGG Vantage West Great West Road Brentford Middlesex TW8 9GG UK Geostatistics is widely used in
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Quantitative Time-Lapse AVO - Initial Application to the Oseberg Field
Authors G.J. Hicks and P. WilliamsonA-19 QUANTITATIVE TIME-LAPSE AVO - INITIAL APPLICATION TO THE OSEBERG FIELD Summary 1 Time-lapse (TL) seismic monitoring has become an increasingly successful tool for reservoir management. Currently we are investigating the possibilities for extracting quantitative information from the time-lapse AVO signature. In general this should allow more precise interpretation of time-lapse observations which is necessary for the future step of direct inversion of time-lapse changes to update reservoir parameters (Rowbotham et al 2001). In this study we show the harmful effect on quantitative TL analysis of substantial acquisition differences between the two seismic vintages used and of strong velocity anomalies
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The Impact of New 4D Seismic Technology on the Magnus Field
Authors B.D. Ritchie, A.G. MacGregor, A. Strudley and R. GotoA-20 THE IMPACT OF NEW 4D SEISMIC TECHNOLOGY ON THE MAGNUS FIELD BRYAN RITCHIE 1 ALAN MACGREGOR 1 ALAN STRUDLEY 2 and RICHARD GOTO 2 Summary 1 Improving both signal bandwidth and repeatability of seismic data are key requirements for reservoir monitoring surveys. This paper details how recent improvements in acquisition systems have impacted these requirements through a case study over the Magnus field in the UK sector of the North Sea. The key objectives of the Magnus survey were to improve seismic resolution of the reservoir and to provide a repeatable 4D baseline survey. The 2001 survey provides a
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Application of the Automatic Factorial Co-Kriging Method (AFACK) to Optimize the 4D Seismic Signature
More LessA-21 APPLICATION OF THE AUTOMATIC FACTORIAL CO-KRIGING METHOD (AFACK) TO OPTIMIZE THE 4D SEISMIC SIGNATURE Summary 1 4D technology is moving into an accelerated phase with several successful projects to date for example in the North Sea and in Canada. As new 4D methodologies emerge we integrate a geostatistical technique into 4D processing. This new method is named AFACK (Auto Factorial Co Kriging) and has been successfully used on several projects in order to increase the repeatability of the seismic data and to optimize the 4D signature. The AFACK technology is used to compensate small variations in time and amplitude
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Joint Geostatistical Inversion of Time-Lapse Data
Authors L.M. Barens, P. Williamson, P. Rowbotham and P. SwabyA-22 JOINT GEOSTATISTICAL INVERSION OF TIME- LAPSE DATA 1 LEON BARENS 1 PAUL WILLIAMSON 1 PETER ROWBOTHAM 1 2 and PETER SWABY 1 3 1. TotalFinaElf Geoscience Research Centre 33 Cavendish Square London W1G 0PW UK 2. Now at: Shell UK Ltd. 3. Now at: BNP Paribas Abstract Inverting time-lapse seismic data to acoustic impedance has potential for enhanced quantitative interpretation of saturation and/or pressure changes in a reservoir. By simultaneously inverting both base and monitor seismic data sets the impedance results are better and more consistently constrained. Using a geostatistical inversion method the time-lapse derived impedance change can be
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Virtual Reality Quality Control in 4D Processing
Authors J. Brittan Inc., M. Widmaier and J. LimaA-23 VIRTUAL REALITY QUALITY CONTROL IN 4D PROCESSING JOHN BRITTAN 1 MARTIN WIDMAIER 2 and JOSTEIN LIMA 2 Introduction 1 The rapid development of stereographic visualization over the last years has given a new dimension to seismic analysis and interpretation. Modern analysis tools have the capability to interactively inspect large 3D data volumes in a virtual environment. The possibility to look simultaneously at several data volumes and attributes in a true 3D sense opens the door to numerous applications. This paper shows how a visualization system is utilized for efficient volume-based quality control in the framework of 4D projects. Volume
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Comparing Time-Lapse Seismic and Reservoir Model Predictions in Producing Oil and Gas Fields
Authors P.J. Hatchell, S. Kelly, M. Muerz, T.C. Jones, P. Engbers, J. van der Veeken and R. StaplesA-24 COMPARING TIME-LAPSE SEISMIC AND RESERVOIR MODEL PREDICTIONS IN PRODUCING OIL AND GAS FIELDS Summary The main value of time-lapse seismic is the additional information to constrain or update a model of the reservoir. Knowledge of reservoir connectivity flow barriers or bypassed hydrocarbons is the kind of information we hope to get from time-lapse data in order to optimize reservoir investment decisions. Though reservoir models are in general constrained by history matching with well production data the solution is most often not unique as the amount of well data is rather sparse compared to time-lapse seismic. 1 A key step
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4D Monitoring of Schiehallion Field, UKCS
Authors C.P. Slater, J. Fletcher, D. Walder, J.M. Marsh and J. MacGregorA-25 4D MONITORING OF SCHIEHALLION FIELD UKCS Summary 1 The principal objectives in acquiring time-lapse (4D) seismic data are to constrain reservoir models and improve reservoir management. To meet these objectives we must estimate the dynamic changes in reservoir properties such as pore pressure and fluid saturation from the 4D seismic data. Until recently this has been done mostly through qualitative interpretations of 4D data. Many qualitative interpretations have been successful especially during the early stages of field life when the changes in reservoir properties are localized around wells and have provided reliable ‘first-order’ constraints to the reservoir model (Parr
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4D-Driven Asset Optimisation
Authors J.G.F. Stammeijer, G. Cooke and H.J. KloostermanA-26 4D-DRIVEN ASSET OPTIMISATION 1 JAN STAMMEIJER GRAHAM COOKE and HENK JAAP KLOOSTERMAN Shell UK Exploration and Production 1 Altens Farm Road Abstract Given the relative maturity of the North Sea as an oil and gas province it is not surprising to see a fast uptake in recent years of 4D time-lapse seismic methods for reservoir monitoring and management 1 . Whereas it is accepted that 4D seismic can have large value in “young” fields in terms of optimising field development decisions and capital expenditure also in mature fields it is found that 4D seismic can add considerable value 2
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The GLISP 4D Monitoring Project - A Lesson in How to Avoid Successful Failure
Authors K. Hirsche, N. Pullin and L. MatthewsA-27 THE GLISP 4D MONITORING PROJECT - A LESSON IN HOW TO AVOID SUCCESSFUL FAILURE KEITH HIRSCHE NORM PULLIN and LARRY MATTHEWS Abstract 1 Hampson Russell Software 510 715 5 th Ave SW Calgary Alta T2P 2X6 Canada A pioneering time-lapse seismic monitoring experiment was performed from 1985 to1987 at the Gregoire Lake In-situ Steam Pilot (GLISP) in Alberta Canada. This project was designed to predict and observe the progress of heat fronts in the tar sand reservoir. The monitoring program was very thorough carefully executed and extremely innovative for it’s time. All aspects of the monitoring process were carefully
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From Qualitative to Quantitative 4D Seismic Analysis of the Gullfaks Field
Authors T. Alsos, A.L. Eide, B.K. Hegstad, N.F. Najjar, D. Astratti, P. Doyen and D. PsailaA-28 FROM QUALITATIVE TO QUANTITATIVE 4D SEISMIC ANALYSIS OF THE GULLFAKS FIELD Abstract 1 To assist the interpretation of reservoir fluid movements in the Gullfaks field a 4D earth model has been created to integrate all the available well seismic and flow simulation data into a common framework. A rock physics model was applied to link the flow simulator output to acoustic impedance and enable the generation of time-dependent synthetic amplitude volumes for comparison with the real seismic amplitude data. Difference volumes derived from the synthetics represent the seismic signature of the fluid movements predicted by the flow simulator. Analysis
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Seismic Modelling of Eclipse Simulations and Comparsion with Real 4D Data at the Norne Field
More LessA-29 SEISMIC MODELLING OF ECLIPSE SIMULATIONS AND COMPARISON WITH REAL 4D DATA AT THE NORNE FIELD BÅRD OSDAL 1 and TRINE ALSOS 2 1 1 Statoil Harstad PO Box 40 9481 Harstad Norway 2 Statoil research center Trondheim Introduction The Norne Field is situated in the southern part of the Nordland II area in the Norwegian Sea approximately 100km north of the Aasgard Fields. The size of the field is approximately 9km x 3km. The reservoir rocks are of Lower and Middle Jurassic age. The hydrocarbon resources consist of a gas cap (25m) mainly situated in the Garn Formation and
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Integrating Time-Lapse Data in the History Match of a Gas-Condensate Reservoir
Authors A.C. Cominelli, R. Seymour, A. Stradiotti and J. WaggonerA-30 INTEGRATING TIME-LAPSE DATA IN THE HISTORY MATCH OF A GAS-CONDENSATE RESERVOIR 1 A. COMINELLI 1 R. SEYMOUR 2 3 A. STRADIOTTI 4 and J. WAGGONER 3 1 Eni/Agip Division Via Unione Europea 3 20097 San Donato Milanese Italy Abstract Time lapse analysis of 3D seismic surveys 4D seismic has been successfully used as a reservoir monitoring tool on several field over the years to detect fluid changes due to production. In this paper we present some novel aspects of a recent application of this technology to a Gulf of Mexico gas condensate reservoir. The field at issue is a
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Time-Lapse Elastic Inversion at the Oseberg Field
Authors H. Rutledal, R. Elde, A.-J. van Wijngaarden, J. Helgesen, H. Buran and T. WeisserA-31 TIME-LAPSE ELASTIC INVERSION AT THE OSEBERG FIELD H. RUTLEDAL 1 R. ELDE 2 AND A-J. VAN WIJNGAARDEN 2 Introduction 1 The Oseberg Field is a major oil and gas field located in the North Sea some 140 km off the coast of Norway. The reservoir comprises sandstones from the Middle Jurassic Brent Group in three eastward-dipping tilted fault-blocks. The northernmost one Alpha North is focused upon in this study. The production from Alpha North started late 1991 with a two front production drive system; gas injection in the initial gas cap and water injection in the water leg. It
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Application of Geostatistical Simulations and Statistical Analysis for Seismic Monitoring
Authors S. Vidal, C. Joseph, F. Gilbert and F. HuguetA-32 APPLICATION OF GEOSTATISTICAL SIMULATIONS AND STATISTICAL ANALYSIS FOR SEISMIC MONITORING Abstract 1 S. VIDAL 1 2 C. JOSEPH 2 F. GILBERT 2 and F.HUGUET 1 Seismic monitoring (time-lapse or 4D seismic) can be considered as an advanced seismic technology. It makes possible to obtain reliable information about fluid distribution in reservoirs. This information can help to provide better decisions and simulate various options to optimize production improve oil recovery and reduce costs. The changes in reservoir fluid saturation pressure and mean stresses induced by reservoir production may influence the process of wave propagation in rocks. Theses changes can be
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Common Reflection Angle Migration
Authors Z. Koren, S. Xu and D. KosloffA-33 COMMON REFLECTION ANGLE MIGRATION Summary 1 We present a 2-D and 3-D ray-based migration/inversion approach for the construction of common image gathers (CIG) in the reflection angle domain. Amplitudes and phases of the reflected events are preserved for a wide range of angles even in complex areas with multi-arrivals. The method can be used for detailed velocity-model determination and for accurate amplitude variation with angle (AVA) analysis in such areas. Our method is a target-oriented approach based on shooting rays from the image points up to the surface. The method can also be applied as a model-based approach by
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Fresnel-Aperture PSDM
Authors H. Tabti and L.-J. GeliusA-34 FRESNEL-APERTURE PSDM Abstract 1 We introduce the Fresnel aperture which is the direct time-domain equivalent at the receivers’ surface of the subsurface Fresnel zone. Based on this concept we propose a new and efficient method for optimal aperture selection and Kirchhoff prestack depth migration. The problem with complex media is that multiple Fresnel apertures apparently exist for a given image point with just one of these corresponding to a possible real geological structure. Hence the contribution from these ‘false’ Fresnel apertures cause a noise-corrupted image of the subsurface. We propose a method by analogy with the velocity analysis where
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Computing Kirchhoff Depth Migration Traveltime from a Monofrequency Wavefield
By J.W. WigginsAbstract 1 A-35 COMPUTING KIRCHHOFF DEPTH MIGRATION TRAVELTIME FROM A MONOFREQUENCY WAVEFIELD WENDELL WIGGINS Prestack depth migration with the Kirchhoff-summation method requires maps of the wave traveltime from each source and receiver location to every image point. These traveltimes are usually computed by ray tracing or a finite-difference solution of the eikonal equation. Either of these methods gives the traveltime at an infinite frequency. In complex structures where the wave at any point is the sum over many slightly different diffracted paths the infinitefrequency times may not produce an ideal result because they do not model the diffraction and recombination
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Ray-Based Anti-Aliasing for Depth Migration
Authors S. Nguyen, R. Baina, M. Noble and P. ThierryA-36 RAY-BASED ANTI-ALIASING FOR DEPTH MIGRATION S.NGUYEN 1 R. BAINA 2 M. NOBLE 1 and P. THIERRY 1 Abstract 1 Operator/Imaging aliasing introduced in Kirchhoff migration is often tackled by trace tapering aperture truncation or a time and offset-variant filtering. The latter being the most suitable. However most implementations and published results using this technique are derived for Kirchhoff time migration and assume a constant velocity media. In this paper we introduce an anti-aliasing filter for ray-based pre-stack depth migration and valid for heterogeneous velocity models. We illustrate the benefits of such a scheme on a numerical and a real
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Aliasing in Wavefield Extrapolation Prestack Migration
More LessA-37 ALIASING IN WAVEFIELD EXTRAPOLATION PRESTACK MIGRATION YU ZHANG 1 JAMES SUN 1 and SAMUEL H. GRAY 2 Introduction 1 Aliasing during migration (“operator aliasing”) is widely recognized as a problem for Kirchhoff migration. It occurs when high-frequency reflection data are swept out at steep angles with the problem being worst for very coarse input trace spacing. The problem can be solved either by data interpolation to a finer-spaced grid of input traces or more commonly by anti-aliasing the migration operator (Gray 1992; Lumley et al. 1994; Abma et al. 2000; Biondi 2001 Zhang et al. 2001a). For two-dimensional (2-D)
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How to Choose a Subset of Frequencies for Frequency-Domain Finite-Difference Migration
Authors R-E. Plessix and W.A. MulderA-38 HOW TO CHOOSE A SUBSET OF FREQUENCIES FOR FREQUENCY-DOMAIN FINITE-DIFFERENCE MIGRATION R.-E. PLESSIX and W.A. MULDER Abstract 1 Frequency-domain finite-difference migration can be accelerated by an order of magnitude if a subset of the available data frequencies is used. To avoid unwanted artefacts the choice of this subset should be guided by two principles: sufficient localisation of reflectors and the avoidance of wrap-around. The first is related to the spatial resolution and Heisenberg’s principle. The second is needed to avoid repetitive patterns and is related to the Nyquist sampling theorem. Here we study both by a simple analytical and
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3D Prestack GSP Migration with Application to a Carbonate Data
Authors S. Jin and J. PajchelA-39 3D PRESTACK GSP MIGRATION WITH APPLICATION TO A CARBONATE DATA 1 EAGE 64 th Conference & Exhibition — Florence Italy 27 - 30 May 2002 1 1 SHENGWEN JIN Summary The generalized screen propagator (GSP) is a one -way wave equation based wide -angle propagator. GSP migration has been applied to both 2-D and 3-D prestack depth migrations for imaging complex velocity structures. Common azimuth offset domain GSP migration is an efficient 3-D prestack wavefield extrapolation algorithm based on double square root (DSR) equation and a stationary-phase approximation for the narrow azimuth nature of marine streamer data. Combined with
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Improving Near-Salt-Flank Imaging with Shot-Profile Wavefield-Extrapolation Migration in the Gulf of Mexico
Authors U.K. Albertin, D. Watts, W. Chang, S.J. Kapoor, C. Stork, P. Kitchenside and D. Yingst1 A-41 IMPROVING NEAR-SALT-FLANK IMAGING WITH SHOT-PROFILE WAVEFIELD- EXTRAPOLATION MIGRATION IN THE GULF OF MEXICO UWE ALBERTIN DAVE WATTS WENFONG CHANG S. JERRY KAPOOR Abstract Prestack Kirchhoff migration is widely used for imaging in complex areas and has been particularly effective in salt and subsalt imaging in the Gulf of Mexico. Despite this success there are areas where Kirchoff migration has difficulty imaging subsalt events. These difficulties are observed near salt flanks and under rugose salt bodies where migration artifacts often obscure primary sediment events. Among the causes for these artifacts are Kirchhoff’s use of a single traveltime arrival approximate
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3D Multi-Arrival Kirchhoff vs. Wave Equation Migration - SEG/EAGE Salt Model Case Study
Authors B. Duquet, G. Lambaré and S. XuA-42 3D MULTI-ARRIVAL KIRCHHOFF VS. WAVE EQUATION MIGRATION - SEG/EAGE SALT MODEL CASE STUDY G. LAMBARE 1 B. DUQUET 2 and S. XU 1 3 1 Abstract In the context of the SEG/EAGE Salt model experiment we compare results obtained by 3D multi-arrival preserved amplitude ray based migration with those obtained by 3D wave equation migration. The same dataset is used but both preprocessing and velocity model differ (for Kirchhoff migration some smoothing had to be applied to the exact velocity model). By the end the better quality of images obtained using wave equation migration with the exact velocity model
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Comparison of Kirchhoff and Wave-Equation Pre-Stack Migration on OBC Data
By R. Soubaras� � �ÇÅÈ�ÊÁËÇÆ Ç� ÃÁÊ�ÀÀÇ�� �Æ� Ï�Î� �ÉÍ�ÌÁÇÆ ÈÊ� ËÌ��à ÅÁ�Ê�ÌÁÇÆ ÇÆ Ç�� ��Ì� ËÙÑÑ�ÖÝ ÊÇ��ÊÌ ËÇÍ��Ê�Ë ��� ÖÙ� Ä��ÓÒ Å���ÙÜ � � Å�××Ý �Ö�Ò � Ì�� Ö� �ÒØ ���×���Ð�ØÝ Ó� ÔÖ� ×Ø� �Û�Ú� �ÕÙ�Ø�ÓÒ Ñ��Ö�Ø�ÓÒ �ÜÔÐ��Ò× Ø�� Ö�Ò�Û�Ð Ó� �ÒØ�Ö�×Ø �Ò Ø��× Ø� �Ò�ÕÙ� Ì��× Ô�Ô�Ö ¬Ö×Ø ��× Ù×× Ø�� ��Ú�ÒØ���× �Ò� �Ö�Û�� �× Ó� Ø�� ��«�Ö�ÒØ �ÜØÖ�ÔÓÐ�Ø�ÓÒ × ��Ñ�× �Ú��Ð��Ð� �ÓÖ Û�Ú� �ÕÙ�Ø�ÓÒ Ñ��Ö�Ø�ÓÒ Ì�� ÕÙ�×Ø�ÓÒ Ó� Û��Ø ØÓ �ÜÔ� Ø �ÖÓÑ � Û�Ú� �ÕÙ�Ø�ÓÒ Ñ��Ö�Ø�ÓÒ ÓÑÔ�Ö�� ØÓ � Ã�Ö ��Ó« ÓÒ� �× Ø��Ò ��Ö�××�� ��×�� ÓÒ � ×ÝÒØ��Ø� �Ò� � Ö��Ð ��Ø� �Ü�ÑÔÐ� ��Ò�ÐÐÝ Ø�� ÔÓ××���Ð�ØÝ Ó�
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Imaging under Complex Salt Bodies with 3D Prestack Finite Difference Depth Migration
Authors Z. Zhou, M. Guo and J.A. SteinA-44 Imaging under complex salt bodies with 3-D prestack finite difference depth migration Summary 1 We present an implicit finite difference depth migration (IFDM) system. Conventional aspects of IFDM are combined to produce a highly accurate downward continuation process. Appropriate imaging and aperture conditions are employed in a shot migration scheme to generate migrated image gathers in the shot-receiver offset domain. A highly efficient parallel implementation has been achieved without sacrificing accuracy. Results are obtained from both standard and in-house datasets from the SEG/EAGE 3-D Salt Model. These results along with real data examples demonstrate the high-quality sub-salt images obtainable
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Prestack Phase-Shift Migration of Separate Offsets in Laterally Inhomogeneous Media
More LessA-45 PRESTACK PHASE-SHIFT MIGRATION OF SEPARATE OFFSETS IN LATERALLY INHOMOGENEOUS MEDIA TARIQ ALKHALIFAH Summary 1 Using the stationary-phase method prestack phase-shift migration is implemented one offset at a time. This separate-offset implementation allows for a Fourier (reasonably fast) wave-equation type migration on data with irregular offset sampling. However the separate-offset phase-shift migration like its zero-offset counterpart handles only vertically inhomogeneous media. Using the combination of the split-step and the phase-shift-plusinterpolation (PSPI) approaches the separate-offset phase-shift migration is extended to handle laterally inhomogeneous media. Like any PSPI-based method the cost of the new migration relies heavily on the complexity of the
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Removing Distortions Caused by Water Velocity Variations - Method for Dynamic Correction
More LessB-01 REMOVING DISTORTIONS CAUSED BY WATER VELOCITY VARIATIONS - METHOD FOR DYNAMIC CORRECTION SCOTT MACKAY and JONATHAN FRIED 1 WesternGeco 1625 Broadway Suite 1300 Denver CO 80222 USA Summary Physical changes in ocean properties may occur during marine acquisition that can cause variations in water velocity. The result is a dynamic difference in traveltimes between overlapping infill data acquired at a later date. Such timing discrepancies may prevent accurate merging and imaging of the data. Unfortunately classical wave-equation solutions to this problem are typically impractical for 3D marine geometries. We present an approximate version of wave-equation layer replacement that addresses
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P-Wave and C-Wave Velocity Analysis for Deep Water OBC Data
Authors W. Wang Inc. and L.D. PhamB-02 P-WAVE AND C-WAVE VELOCITY ANALYSIS FOR DEEP WATER OBC DATA WEIZHONG WANG and LONG DON PHAM Summary 1 Deep-water OBC data are collected with sources and receivers at different depths. Seismic velocity estimation algorithms commonly used in processing assume that sources and receiver are at the same datum. To satisfy this requirement vertical shifts are applied to the data or straight ray projections are performed to bring shots and receivers to the same datum. If the sampling of the acquisition geometry is adequate then wave-equation datuming can also be applied. In this paper we present formulae for Pwave and
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Stacking Velocity Analysis with CRS Stack Attributes
Authors S. Bergler, P. Chira, J. Mann, K. Vieth and P. HubralB-03 STACKING VELOCITY ANALYSIS WITH CRS STACK ATTRIBUTES S. BERGLER P. CHIRA J. MANN K. VIETH and P. HUBRAL Geophysical Institute University of Karlsruhe Hertzstr. 16 76187 Karlsruhe Germany Abstract The Common-Reflection-Surface (CRS) Stack has been established over the past years as an alternative to standard data-driven imaging techniques. The CRS Stack not only yields high-quality stack sections from multi-coverage reflection pre-stack data but also provides—as by-product to the stacked section— important wavefield attributes. With the knowledge of the near-surface velocity only these attributes can be extracted from the stacking parameters which constitute the Common-Reflection-Surface stacking operator. The wavefield attributes
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Calibration of Depth Imaged Seismic Data Using an Interval Velocity Scaling Method
Authors A.A. Curtis, D.D. Stoughton, D.R. Hill, J.F. Ratcliffe and T. HartnettB-04 CALIBRATION OF DEPTH IMAGED SEISMIC DATA USING AN INTERVAL VELOCITY SCALING METHOD Summary 1 A. A. CURTIS D. D. STOUGHTON D. R. HILL J. F. RATCLIFFE and T. HARTNETT BHP Billiton Petroleum 1360 Post Oak Boulevard Houston TX 77056 USA As a consequence of anisotropy and other imaging effects horizon markers extracted from 3D seismic amplitude data frequently do not tie the equivalent formation intersections determined from well data. Such mis-ties between the seismic and well-log based formation markers can be quite significant in many Gulf of Mexico fields and are likely to be present in any 3D depth
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Pre Conditioning of the Densely Sampled Stacking Velocity Field
Authors D. Le Meur and P. HerrmannB-05 PRE CONDITIONING OF THE DENSELY SAMPLED STACKING VELOCITY FIELD Abstract 1 Over the last few years efficient methods have been developed to estimate densely sampled stacking velocity fields with the aim to improve the S/N ratio the spatial resolution and the frequency content of the stack. As a by-product this densely sampled attribute cube also becomes open to interpretation. The raw estimate of the automatically derived attribute is however too ‘noisy’ for immediate use. Fortunately the dense spatial and temporal sampling allows the use of efficient pre conditioning steps with a clear impact on the NMO stack result. Introduction
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The Key Practical Aspects of 3D Tomography - Data Picking and Model Representation
Authors F.J. Billette, J.T. Etgen and W.E. RietveldB-06 THE KEY PRACTICAL ASPECTS OF 3D TOMOGRAPHY - DATA PICKING AND MODEL REPRESENTATION Abstract 1 There are a wide variety of approaches to building velocity models with prestack depth migration. The most common pitfalls we see in them are extracting reliable yet detailed information about velocity errors from migrated data and then the inability to produce geologically reasonable velocity models from these error estimates. We extract detailed error estimates along horizons from finely sampled migrated data edit them statistically and QC the edits in map view. Tomography converts these error estimates into new velocity models or velocity model updates
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Model-Driven Data Interpolation vs. Velocity Knowledge Uncertainties
Authors P. Mazzucchelli, N. Bienati and U. SpagnoliniB-07 Model-driven data interpolation vs. velocity knowledge uncertainties. P. MAZZUCCHELLI 1 N. BIENATI 2 U. SPAGNOLINI 1 Abstract 1 Model-driven data interpolation performed by continuation algorithms (i.e. 3D SMO – Shot MoveOut) exploits the redundancy of the prestack data to regularize/densify survey geometries. Their usual Kirchhoff-type kernel implies that the accuracy of interpolation results is directly linked to the coverage of the operator itself [2] then coverage must be properly defined. A simple scalar index (e.g. fold of coverage) is not enough as it does not account for uneven dip illumination. Moreover the sensitivity of the continuation operators to velocity
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3D Stereotomographic Inversion on Real Data Set
Authors E. Chalard, P. Podvin, S. Le Bégat, P. Berthet and B. DavidB-08 3D STEREOTOMOGRAPHIC INVERSION ON REAL DATA SET Abstract 1 EMANUEL CHALARD 1 3 PASCAL PODVIN 1 SOAZIG LE BEGAT 1 PHILIPPE BERTHET 2 BERNARD DAVID 3 Stereotomography is a new tomographic method introduced in 2D by Billette and Lambaré (1998). It uses the apparent slopes of locally coherent seismic events picked in the prestack data cube to constrain the velocity model. In previous papers (Chalard et al. 2000a 2000b) we introduced the extension of stereotomography to 3D. In particular we proved that in the case of multi-streamer marine data acquisition the picking of seismic events can be performed independently
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Amplitude-Preserving Monte Carlo 3D Prestack Migration
Authors L. Cazzola, M.T. Arienti, E. Bonomi and G. CardoneB-09 AMPLITUDE-PRESERVING MONTE CARLO 3D PRESTACK MIGRATION Abstract 1 We present an amplitude-preserving imaging condition based on a least-squares approach that applies to Monte Carlo wavefield migration methods. Its implementation requires the knowledge of the overall shot illumination map that can be computed at a negligible additional cost during the migration process. The resulting condition is not sensitive to instability effects usually plaguing other formulations. Furthermore it compensates irregular shot illumination and focusing/defocusing effect caused by the velocity field. Finally we show how the shot illumination volume is used as an independent tool for a better interpretation of seismic data.
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Pre-Stack Time Migration for Rough and Rugged Mountain Areas
More LessB-10 PRE-STACK TIME MIGRATION FOR ROUGH AND RUGGED MOUNTAIN AREAS Summary 1 Seismic imaging algorithms commonly used in production like NMO DMO pre-stack and post-stack migration are only applied to data that have been datumed to a planar surface. This is because conventional seismic imaging algorithms have an assumption that the shot and receiver of a seismic trace are located at the same elevation. This assumption is restrictive and cannot be satisfied in mountain areas with rough and rugged topography. There are two approaches to address this problem: wave-equation datuming or migration from topography. Here we developed a 3-D pre-stack
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Amplitude Preserving v(z) Pre-stack Kirchhoff Migration, Demigration and Modeling
Authors C. Notfors, Y. Zhang, M. Karazincir, J. Sun and B. HungB-11 AMPLITUDE PRESERVING V(Z) PRE-STACK KIRCHHOFF MIGRATION DEMIGRATION AND MODELING 1 Summary We analyze the true amplitude weights in time migration and demigration based on Bleistein’s Kirchhoff inversion and modeling formulas. In addition a geometrical spreading factor is derived for any dipping reflector in a v (z) medium. Finally we propose proper anti-aliasing formulas honoring sampling theory to preserve fidelity for 3-D migration and demigration. Introduction Kirchhoff prestack time migration is widely used in 3-D seismic data processing while Kirchhoff demigration is a useful tool to obtain a zero-offset data volume after Kirchhoff prestack time migration and stack. Arbitrary weights
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Wavefront Construction Kirchhoff Migration with Ray-Amplitude Corrections
Authors M.C. Fehler, S.T. Hildebrand, L.J. Huang and D.X. AldeB-12 Wavefront Construction Kirchhoff Migration with Ray-Amplitude Corrections 1 Michael C. Fehler Steven T. Hildebrand Lianjie Huang and Douglas Alde MS D443; Los Alamos National Laborartory; Los Alamos NM 87545; USA Summary: Kirchhoff migration using ray tracing travel times has been a popular imaging method for many years. However there are significant limitations in the ability of Kirchhoff migration to reliably image regions of complex structure when using only first arrivals. Thus new methods for imaging have been sought. One approach for improving imaging capability is to use ray tracing methods that allow the calculation of multiple-valued travel time tables
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Construction of Single-Valued Ray Field Maps in the Position/Angle Domain for Ray-Based Imaging with Multiple Arrivals
Authors D.A. Kraaijpoel, R.K. Snieder and K. Roy-ChowdhuryB-13 CONSTRUCTION OF SINGLE-VALUED RAY FIELD MAPS IN THE POSITION/ANGLE DOMAIN FOR RAY-BASED IMAGING WITH MULTIPLE ARRIVALS Summary DIRK KRAAIJPOEL 1 ROEL SNIEDER 2 and KABIR ROY-CHOWDHURY 1 1 Utrecht University Faculty of Earth Sciences Budapestlaan 4 3582 CD Utrecht The Netherlands 2 Center for Wave Phenomena and Dept. of Geophysics Colorado School of Mines Golden CO 80401-1887 USA We present a new approach to the representation and generation of ray field maps (traveltimes amplitude etc. ) for use in ray-based imaging techniques. For the new representation of ray field data we make use of the fact that the source
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Offset Plane Wave Migration
Authors D.J. Foster, C.C. Mosher and S. JinB-14 Offset Plane Wave Migration Abstract In spite of advances in computing hardware full aperture 3D pre-stack wave equation shot record migration of marine streamer data remains a significant challenge. Like common azimuth migration offset plane wave migration provides a means for reducing the number of computations required for full aperture wave equation imaging of azimuthally limited datasets. Offset plane wave migration algorithms are derived from common azimuth phase screen migrations by replacing the Fourier transforms over the offset coordinate with a stationary phase mapping between offset ray parameter in the wavenumber domain and offset in the space domain. This
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3D Zero Offset-Common Reflection Surface Stack for Land Data - Real Data Example
Authors P. Marchetti, A. Cristini and G. CardoneB-15 3D ZERO-OFFSET COMMON REFLECTION SURFACE STACK FOR LAND DATA - REAL DATA EXAMPLE 1 ANTONIO CRISTINI 1 GIOVANNI CARDONE 1 and PAOLO MARCHETTI 2 Summary. The macro-model independent Zero-Offset Common Reflection Surface stacking technique has been established as an improvement of the conventional NMO/DMO processing. Over the past years it has been successfully applied both to 2D synthetic and real multi-coverage data and only recently a 3D implementation was developed and tested on a synthetic data set. We present and discuss an implementation of the CRS stack that applies to 3D real data. The first satisfactory results on a
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Improved Resolution in Time and Depth Processing by Macro-Model Independent CRS Stacking
Authors G. Gierse, H. Trappe and J. PruessmannB-16 Improved resolution in time and depth processing by macro-model independent CRS stacking H. Trappe G. Gierse and J. Pruessmann TEEC Trappe Erdoel Erdgas Consultant Burgwedeler Str. 89 30916 Isernhagen Germany Macro-model independent imaging techniques have received increasing attention in seismic exploration in recent years. Based on this technical strategy the Common-Reflection-Surface (CRS) method has proved to be a valid alternative to conventional NMO/DMO processing. Numerous application examples demonstrate the increase in resolution by this technique. The superior signal-to-noise ratio and reflector continuity are supplemented by an enhanced imaging of structural details and dipping elements. Both these imaging advantages and
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Local Imaging Approach and Applications
Authors I. Lecomte, L.-J. Gelius and S.-E. HamranB-17 LOCAL IMAGING APPROACH AND APPLICATIONS Summary 1 Local imaging obtained using a local plane-wavenumber approach of Generalized Diffraction Tomography is very similar to Synthetic Aperture Radar imaging in spotlight-mode acquisition. A local image of the scattering structures around any point in a model is calculated using ray-based Green’s functions computed at that point only. The cost of the local imaging is very small compared to classic imaging which needs grids of Green’s functions. The signal-processing approach inherent to this FFT-based local imaging allows also a very powerful and flexible imaging with full control of aliasing and noise filtering. The
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Constrained Least-Squares Wave-Equation Migration for AVP Inversion
Authors H. Kuehl and M.D. SacchiB-18 CONSTRAINED LEAST-SQUARES WAVE- EQUATION MIGRATION FOR AVP INVERSION Abstract 1 Wave-equation migration is known to be beneficial for structural imaging in complex geological settings. Recently imaging principles have been developed that allow for the extraction of amplitude variations as a function of angle or offset ray-parameter (AVA or AVP) from the downward continued wavefield. We propose the least-squares (LS) approach to wave-equation migration in order to generate high quality AVP common image gathers (CIGs). As we have previously demonstrated with the Marmousi dataset least-squares imaging with a smoothing constraint on the AVP CIGs can mitigate artifacts. Here we study
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SIGSBEE_2A Synthetic Subsalt Dataset - Image Quality as Function of Migration Algorithm and Velocity Model Error
Authors J. Paffenholz, J. Stefani, B. McLain and K. BishopB-19 SIGSBEE_2A SYNTHETIC SUBSALT DATASET - IMAGE QUALITY AS FUNCTION OF MIGRATION ALGORITHM AND VELOCITY MODEL ERROR 1 Summary Producing consistent production-quality seismic images sub-salt within the deepwater Sigsbee escarpment province of the Gulf of Mexico remains today an unsolved technical challenge. To help gain insight into the imaging failure mechanism(s) and to facilitate research into potential imaging solutions the SMAART JV constructed a 2D model containing a distorting salt lens and calculated a 2D acoustic Finite Difference numeric dataset. This dataset was used to investigate a) the relationship between imaging algorithms and 2D sub-salt image quality and b) the
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Imaging the Unimaginable
Authors A.J. Deighan, H. Crook and R. BlowB-20 IMAGING THE UNIMAGINABLE Introduction 1 Even as a mature area the Southern North Sea presents one of the most challenging areas for Prestack Depth Migration (PreSDM). Constrained by project schedules and costs we present a case history where we have integrated ambiguous borehole and seismic data in a structurally complex area resulting in significant changes to the geological interpretation. General geological setting The area of interest lies in the Dowsing Fault Zone (DFZ) on the western margin of the Southern North Sea. The northeasterly dipping fault zone separates the relatively stable East Midlands shelf from the tectonically active Sole
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Pre-Stack Depth Migration Netherlands an Integrated Methodology - Processing, Interpretation, Algorithm Development
Authors G. Desrousseaux, L. Lemaistre, P. Sexton and P. WilliamsonB-21 PRE-STACK DEPTH MIGRATION NETHERLANDS - AN INTEGRATED METHODOLOGY PROCESSING INTERPRETATION ALGORITHM DEVELOPMENT Introduction 1 A 3D Pre-Stack Depth Migration (PSDM) has been carried out on a Netherlands block case study with the aim of improving the imaging and minimising the structural uncertainty. The prospect is in a structurally complex environment beneath a 3000m high salt diapir. The sensitivity of PSDM to the input velocity model is well understood. In previous publications [5] we have proposed adaptations of tomographic model building techniques to deal with complex tectonics. In this paper we would like to focus more on the importance and
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Angle Tomography
Authors S. Brandsberg-Dahl, B. Ursin and M.V. de HoopB-22 ANGLETOMOGRAPHY SVERRE BRANDSBERG-DAHL 1 BJORN URSIN 2 and MAARTEN V. DE HOOP 3 1 BPAmerica Inc. Houston TX 77079 USA. Formerly: Colorado School of Mines Golden CO80401 USA 2 Norwegian University of Science and Technology N-7491 Trondheim Norway 3 Center for Wave Phenomena Colorado School of Mines Golden CO80401 USA Abstract Wepresent amethod for migration velocity analysis in complex media that does not depend on picking traveltime misfits or residual moveout in common image gathers (CIGs). Our method constructs CIGs in the scattering-angle/azimuth domain where we apply semblance or differential semblance to measure the coherency of events. Since amplitude
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A Comparison of Ray-Based and Waveform Tomography - Implications for Migration
Authors R.G. Pratt, F. Gao, C. Zelt and A. LevanderB-23 A comparison of ray-based and waveform tomography: implications for migration Introduction 1 Seismic ray-based tomography has proven to be an effective imaging tool in many applications. More recently the technique of waveform tomography has emerged in which we use wave-theoretical methods and the direct arrival waveform. The distinctions that arise in tomography are an analogue for the distinctions between ray-based (Kirchhoff) methods and “wave-equation” methods used in migration: in most implementations of ray-based tomography (and Kirchhoff migration) events are assumed to be adequately represented by their (single valued) arrival times while a wave-theoretical approach treats the wavefield as a
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Toward Accurate Velocity Models by 3D Tomographic Velocity Analysis
More LessB-24 TOWARDS ACCURATE VELOCITY MODELS BY 3D TOMOGRAPHIC VELOCITY ANALYSIS Summary 3-D prestack depth migration has become a routine process for depth imaging. However the image quality depends strongly on the accuracy of the velocity model. For post-migration tomographic analysis bad data (picks) null space and intrinsic non-linearity may degrade the quality of the velocity model. In our tomography implementation we use several tools to address these problems. First we automatically pick a large number of depth residuals without requiring lateral continuity along horizons. In the solver we apply a left preconditioning operator resulting from the L norm to reduce
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Defining Lateral Velocity Variations to Improve Reservoir Mapping with New Seismic Measurements while Drilling, Leadon Field, UK
Authors S.J. Bevali, P.T. King, G. Templeton and M.L. ReederB-25 DEFINING LATERAL VELOCITY VARIATIONS TO IMPROVE RESERVOIR MAPPING WITH NEW SEISMIC MEASUREMENTS WHILE DRILLING LEADON FIELD UK Abstract 1 PHILIP KING 1 GERHARD TEMPLETON 1 MARK REEDER 1 and STEPHANE BEVALI 2 1 Kerr-McGee North Sea (U.K.) Ltd 2 Schlumberger Kirkton Avenue Aberdeen AB21 0BF UK During velocity model building of the Leadon field Kerr-McGee had recognized lateral velocity variations. However it has proved difficult to model and integrate the uncertainties associated with these velocity variations particularly in planning long horizontal development wells (up to 5000 ft MD). The present article illustrates how we used the new Seismic Measurement
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Comparison of Full Waveform SeismicMWD and Conventional VSP Data from the South Caspian
Authors J.B.U. Haldorsen, M. Krasovec, S. Raikes, T. Harrold, D.N. Day and J.D. ClippardB026 Comparison of Full Waveform SeismicMWD and conventional VSP data from the South Caspian 1 J.B.U. Haldorsen 1 M. Krasovec 2 S. Raikes 3 T. Harrold 3 and D.N. Day 3 J.D. Clippard 4 1 Schlumberger-Doll Research Old Quarry Road Ridgefield CT06877-4108 USA 2 Earth Resources Laboratory Massachusetts Institute of Technology 42 Carleton St. Cambridge MA 02142 3 BP Chertsey Road Sunbury on Thames Middlesex TW16 7LN UK 4 Shell E&P Technology Appl. & Research Volmerlaan 8 Postbus 60 2280AB Rijswijk The Netherlands Abstract We demonstrate that full waveform data acquired while drilling using the new Schlumberger Seismic Measurement While
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A Migration Method for Limited Seismic Array Geometries - Application to Reverse VSP
Authors M.L. Krasovec, W. Rodi, R. Turpening, R.T. Coates and M.N. ToksözB-27 A MIGRATION METHOD FOR LIMITED SEISMIC ARRAY GEOMETRIES - APPLICATION TO REVERSE VSP Summary 1 Images produced from seismic data collected with limited arrays such as downhole seismics or surface seismics with incomplete arrays tend to contain artifacts resembling migration smiles. These artifacts are often suppressed by severely limiting the migration dip aperture which can also omit dipping reflectors and detract from the quality and usefulness of the image. To maximize the imaging capabilities of such datasets a new imaging approach has been developed to compliment conventional migration methods. The new approach termed vector image isochron (VII) migration minimizes
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Planning, Acquiring and Processing a Walkaround VSP for Fracture Induced Anisotropy
Authors S.A. Horne, C. Thompson, R. Moran, J. Walsh, J. Hyde and E. LuiB-28 PLANNING ACQUIRING AND PROCESSING A WALKAROUND VSP FOR FRACTURE INDUCED ANISOTROPY 1 Introduction The Rangely field Western Colorado is a large monoclinal structure with gentle dips of less than 4 degrees at the reservoir depth of approximately 1.7km. The principal reservoir rock is the lower Pennsylvanian Weber formation which is a massive fine-grained aeolian sandstone exhibiting cross-bedding. The Weber formation is mostly overlain by shales with some sandstones. Rangely is a mature field discovered in 1933. Since initial production in the 1940s the field has undergone pressure depletion followed by water injection and now CO2 miscible flood. Injector-producer pattern
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How to Calculate and to Interpret Uncertainties on Walkaway Imaging
Authors J.B. Blanco and J.-C. BoisseauB-29 HOW TO CALCULATE AND TO INTERPRET UNCERTAINTIES ON WALKAWAY IMAGING 1 JACQUES BLANCO 1 and JEAN-CHRISTOPHE BOISSEAU 2 1 TOTALFINAELF Exploration Avenue Larribau 64018 Pau CEDEX France Abstract In the discovery appraisal and development phases of a field walkaway imaging can be a useful tool for a good description around a well. Nevertheless a question can be addressed concerning the confidence that we can have for interpreting the walkaway image especially when the image is only 2-D not 3-D. The quantification of uncertainties is a way to solve the problem. The experience has shown that the most important uncertainties
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Monte Carlo Bayesian Look-Ahead Inversion of Walkaway Vertical Seismic Profiles
Authors A. Malinverno and W.S. LeaneyB-30 Monte Carlo Bayesian Look-Ahead Inversion of Walkaway Vertical Seismic Profiles Abstract 1 We describe a method to invert a walkaway VSP (WVSP) data set and predict VP VS and density in a layered medium while “looking-ahead” of a receiver. Using a Bayesian approach we define a posterior distribution of layered media that is the product of a prior distribution (which contains information on the overall variability of and correlations among VP VS and density and is based on well logs) and of a likelihood function (which quantifies how well a layered medium fits the WVSP data). We then use
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Seismic Anisotropy from VSP - Pre-SDM in Pierce Field, Central North Sea
Authors T.L. Armstrong, S. Merlin and K. HawkinsB-31 SEISMIC ANISOTROPY FROM VSP – PRE-SDM IN PIERCE FIELD CENTRAL NORTH SEA Summary 1 Poor seismic data quality and significant well misties in excess of 100ms adjacent to salt diapirs on 3D post-stack depth migration (post-SDM) data in the Pierce Field led to seismic re-processing with anisotropic pre-stack depth migration (pre-SDM). Here we describe how we initially determined the presence of seismic anisotropy within the overburden using ‘legacy’ VSP data and how this was subsequently confirmed during seismic velocity analysis. Introduction and Nature of the Problem Pierce Field lies in Blocks 23/22a and 23/27 of the UK central North
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Derivation of Anisotropic Parameters for Prestack Depth Migration Using a Walkaway VSP
Authors P.J. Whitfield, R.I. Bloor and C. LangeB-32 DERIVATION OF ANISOTROPIC PARAMETERS FOR PRESTACK DEPTH MIGRATION USING A WALKAWAY VSP Abstract 1 PHIL WHITFIELD¹ ROBERT BLOOR² and CHRISTIAN LANGE³ ¹WesternGeco Schlumberger House Buckingham Gate Gatwick Airport W Sussex RH6 0NZ UK It is becoming common practice to incorporate anisotropy into velocity-depth models for prestack depth migration (PSDM) most often with a vertical transverse isotropy (VTI) assumption. The benefits are not only a good well tie but also significantly improved imaging particularly in the presence of steep dips. The anisotropy is usually specified using Thomsen’s parameters epsilon and delta (Thomsen 1986) which in North Sea Tertiary sediments are
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Anisotropic Inversion of Seismic Data for Stressed Media - Theory and a Physical-Modeling Study on Berea Sandstone
Authors D. Sarkar, A. Bakulin and R. KranzB33 ANISOTROPICINVERSIONOFSEISMIC DATA FOR STRESSEDMEDIA: THEORYAND A PHYSICAL-MODELINGSTUDYONBEREA SANDSTONE DEBASHISHSARKAR 1 ANDREYBAKULIN 2 andROBERTL. KRANZ 1 Summary 1 GeophysicsDepartment ColoradoSchool of Mines Golden CO80401USA 2 Formerly Schlumberger Cambridge Research Cambridge England; Presently ShellInternational Exploration and Production Houston USA Non-hydrostatic stress applied to an initially transversely isotropic medium with avertical symmetry axis (VTI) results in an effectivemedium having almost orthorhombic symmetry (provided that one of the principal stresses is aligned with the symmetry axis). The symmetry planes in this orthorhombicmedium arealignedwiththe orientationsof theprincipalstresses and theTsvankin anisotropicparameters( ¢¡¤£¦¥ §©¨ � ¡�£¦¥ §�¥ �©¨ and� ¡�£¦¥ §©¨ )canrevealinformationaboutthestressmagnitudes. Therefore time-lapse monitoring of changesin
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Predicting Velocities under Stress in Anisotropic Formations - Model and Experimental Validation
Authors R. Prioul and A. Bakulin� � ÈÖ��� Ø�Ò� Ú�ÐÓ �Ø��× ÙÒ��Ö ×ØÖ�×× �Ò �Ò�×ÓØÖÓÔ� ËÙÑÑ�ÖÝ �ÓÖÑ�Ø�ÓÒ×� ÑÓ��Ð �Ò� �ÜÔ�Ö�Ñ�ÒØ�Ð Ú�Ð���Ø�ÓÒ Ê ÈÊÁÇÍÄ �Ò� � ��ÃÍÄÁÆ � Ë �ÐÙÑ��Ö��Ö ��Ñ�Ö���� Ê�×��Ö � À��� �ÖÓ×× Å���Ò�Ð�Ý ÊÓ�� ��Ñ�Ö���� �� �Ä �Ò�Ð�Ò� ÆÓÛ �Ø Ë��ÐÐ ÁÒØ � È ÀÓÙ×ØÓÒ ÍË� �×Ø�Ñ�Ø�Ò� ×Ù�×ÙÖ�� � ×ØÖ�×× ÓÖ ÔÓÖ� ÔÖ�××ÙÖ� �ÖÓÑ ×��×Ñ� Ú�ÐÓ �Ø��× ØÝÔ� �ÐÐÝ Ö�Ð��× ÓÒ ×Ô� �¬ Ô�ØÖÓÔ�Ý×� �Ð Ö�Ð�Ø�ÓÒ×��Ô× ÅÓ×Ø Ó� Ø�� ÓÑÑÓÒÐÝ Ù×�� Ú�ÐÓ �ØÝ ×ØÖ�×× �ÕÙ�Ø�ÓÒ× �Ö� ��×��Ò�� �ÓÖ �×ÓØÖÓÔ� Ñ���� �Ò� ��× Ö��� ×�Ò�Ð� È ÓÖ Ë Û�Ú� Ú�ÐÓ �ØÝ Ú�Ö×Ù× ÓÒ¬Ò�Ò� ×ØÖ�×× ÓÖ ��ÔØ� �ÔÔÐÝ�Ò� ×Ù � Ö�Ð�Ø�ÓÒ×��Ô× ØÓ �Ò�×ÓØÖÓÔ� �ÓÖÑ�Ø�ÓÒ× ÙÒ��Ö
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Stress Dependences of Seismic Velocities in Porous and Fractured Rocks
Authors S.A. Shapiro and V.N. TroyanB-35 STRESSDEPENDENCESOFSEISMIC VELOCITIESINPOROUSANDFRACTURED ROCKS SergeA.Shapiro 1 andVladimirN.Troyan² 1 FreieUniversitätBerlin FachrichtungGeophysik Malteserstr.74 -100 12249Berlin Germany ²St.PetersburgStateUni versity Russia Summary EAGE64thConference&Exhibition —Florence Italy 27 -30May2002 1 Using quite general results of the poroelasticity theory we analyze the influence of the confining stress and of the pore pressure on seismic velocities in rocks. In the first approximation the seismic velocities as well as the porosity depend on the differential stress. We show that the stress dependence of the elastic moduli is controlled by the stress dependence of the porosity. The most important role is played by the compliant porosity which can be just
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Stress Effects of Core Samples - Do They Aid in Time-Lapse Seismic?
By A. FurreB-36 STRESS EFFECTS OF CORE SAMPLES; DO THEY AID IN TIME-LAPSE SEISMIC? Abstract 1 Performing laboratory measurements on core samples is the usual method to obtain stress dependency of a formation’s framework velocities. More than 150 core sample measurements from eight fields in the Norwegian sector illustrate that there is a large spread in the stress dependency of velocities. This is attributed to micro-structural differences between the samples such as cementation and texture in addition to possible core damage. Introduction In time-lapse (4D) seismic studies several velocity controlling mechanisms must be evaluated in order to estimate the changes in seismic
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Application of Anisotropy in Pore Pressure Prediction
Authors N.C. Banik, A. Banik, G. Wool, G. Schultz, N.C. Dutta, R. Marple, T. Casper and N. ReparB-37 APPLICATION OF ANISOTROPY IN PORE PRESSURE PREDICTION Summary The vertical component of the P-wave interval velocity or slowness is the main ingredient in pore pressure prediction and seismic data are the main source of acoustic velocity estimation. It is known that most sedimentary rocks especially well-consolidated shales display anisotropy characteristics and that conventional velocity analysis method cannot provide vertical velocity in the presence of anisotropy. In a companion paper our co-workers discuss estimation of vertical velocity in the presence of transverse isotropy. In this paper we present application of transverse isotropy (TI) in pore-pressure prediction. We present pertinent formula
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Poisson’s Ratio and Pore Pressure Estimation
Authors J. Dvorkin and J.D. WallsB-38 POISSON’S RATIO AND PORE PRESSURE ESTIMATION Abstract By analyzing experimental data we show that in many gas-filled rocks the Poisson's ratio (PR) decreases with decreasing differential pressure (confining minus pore pressure). In many liquid-saturated rocks the opposite is true: PR increases with decreasing differential pressure. This means that in gas-saturated rocks PR decreases with increasing pore pressure and in liquid-saturated rocks it increases with increasing effective pressure. We confirm the generality of the observed effect by theoretically reproducing it via effective medium modeling. This effect can be used as a new tool for seismic pore pressure and pore fluid
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Compliance-Based Laws for the Dry-Frame Pressure Sensitivity of Sandstones
By C. MacBethB-39 COMPLIANCE-BASED LAWS FOR THE DRY- FRAME PRESSURE SENSITIVITY OF SANDSTONE Abstract 1 General laws are put forward to describe the sensitivity of elastic properties to hydrostatic stress as measured in the laboratory on unsaturated reservoir core and outcrop sandstones. The theoretical basis for these relations is the use of excess compliance as a pseudo-function to describe all internal weaknesses in the rock regardless of their origin. Each elastic modulus M is specified by the maximum possible pressure variation SM a rate parameter PM (both weakly dependent on porosity) and the high-pressure asymptote M (linearly dependent on porosity). The new
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Gassmann’s Equation and Frequency Dependent Elastic Response - an Experimental Study
Authors R. Hofmann, M. Batzle and D. HanB-40 GASSMANN’S EQUATION AND FREQUENCY DEPENDENT ELASTIC RESPONSE – AN EXPERIMENTAL STUDY Abstract 1 The frequency dependent response of an artificial rock sample was measured in the frequency range between 3 Hz and 500 kHz and compared to the Gassmann prediction which is the low frequency limit of the fluid response. The low frequency response shows a good agreement with the prediction while the ultrasonic measurements especially at partial saturations show a large difference and can better be described with a theory like patchy saturation. Introduction Gassmann (1951) used linear elasticity to calculate the effect of fluids in a porous
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Rock Physics Diagnostic in Sand/Shale Sequence
Authors J. Dvorkin, M.B. Carr and T. BergeB-41 ROCK PHYSICS DIAGNOSTIC IN SAND/SHALE SEQUENCE Abstract 1 The rock physics diagnostic is a procedure of establishing a rational effective-medium-based transform between the elastic and bulk properties of the sediment. A typical example of such transform is a porosity-impedance relation. Often the rock physics diagnostic allows the geoscientist to relate the elastic properties not only to the sediment bulk properties but also to its conditions such as effective pressure and saturation. The main purpose of the rock physics diagnostic is to derive reservoir properties and conditions from seismic data by e.g. directly applying a rock physics transform to an
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Shear Velocity Prediction in the Norwegian Sea
Authors L.B. Hubert, M.B. Carr and J. DvorkinB-42 SHEAR VELOCITY PREDICTION IN THE NORWEGIAN SEA Abstract Well-bore derived measurements provide a link through rock physics to the seismic domain. Shear wave velocity log data is important for many aspects of seismic modeling including offset synthetic seismogram generation and half space modeling for AVO analysis. Due to the relatively recent advent of shear wave velocity logs (VS) VS data is in many instances missing or unreliable. However as compressional velocity logs (VP) are widely available a local empirical transform relating VP to VS would be useful. Several authors have published methods for predicting shear wave velocities in the
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Stable Extraction of Fundamental Rock Properties from Seismic Data
By F.D. GrayB-43 STABLE EXTRACTION OF FUNDAMENTAL ROCK PROPERTIES FROM SEISMIC DATA Abstract A new method for the extraction of the fundamental rock properties expressed by Lamé’s parameters Lamé’s constant (λ) and shear rigidity (µ) from pre-stack seismic data is proposed. It will be shown that this new method is more stable and less ambiguous than the method currently used to extract these parameters. 1 Introduction It is easier to understand the connection of fundamental rock properties such as compressibility and rigidity to reservoir properties than it is for traditional seismic attributes like amplitude and velocity (Gray and Andersen 2000). Goodway et
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Impact of Linking Petrophysical Parameters in Monte Carlo Simulation of Oil-In-Place
By B. HarrisonB-44 IMPACT OF LINKING PETROPHYSICAL PARAMETERS IN MONTE CARLO SIMULATION OF OIL-IN-PLACE Abstract 1 There is nothing new in estimating Oil-In-Place (OIP) using Monte Carlo simulation and many observers have noted the interdependency between the key petrophysical parameters. However even though it is relatively easy to combine input parameters in modern Monte Carlo software packages it appears that it is rarely done. This is sometimes due to geo-scientist having little data to evaluate dependency between variables. There is also a generally held belief that as the OIP exercise is so uncertain there is no need to bother linking particular parameters.
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Fluid Saturation from Well Logs Using Modular Neural Networks
Authors H.B. Helle, A. Bhatt and B. UrsinB-45 FLUID SATURATION FROM WELL LOGS USING MODULAR NEURAL NETWORKS 1 Abstract In this study we developed and tested a modular artificial neural network system for predicting underground fluids water oil and gas and their partial saturations directly from well logs without explicit knowledge of the fluid and rock properties as required by conventional methods. Based on laboratory data on relative permeability for alternative fluid systems oil-water or gas-oil respectively the relative permeability logs may also be provided for input to reservoir simulation while drilling. Simple three-layer back-propagation artificial neural networks (BP-ANN) constitute the building blocks of a modular system
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Velocity and Attenuation in Partially Saturated Rocks - Numerical Experiments
Authors H.B. Helle, N.H. Pham and J.M. CarcioneB-46 VELOCITY AND ATTENUATION IN PARTIALLY SATURATED ROCKS - NUMERICAL EXPERIMENTS 1 Abstract Using a numerical solution of Biot's poroelastic wave equation we conduct wave propagation experiments in a rock sample with partial saturation using fluid distribution patterns from published tomography scans and for frequencies in the range 10 to 500 kHz. The model rock is a homogeneous isotropic sandstone partially filled with gas and water using their characteristic values of viscosity compressibility and density. No mixing is assumed and the two different pore-fills occupy different macroscopic regions of the model. The von Kármán self-similar correlation function is used employing
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Attenuation of Acquisition Footprint for Non-Orthogonal 3D Geometries
By R. Soubaras� � �ÌÌ�ÆÍ�ÌÁÇÆ Ç� ��ÉÍÁËÁÌÁÇÆ �ÇÇÌÈÊÁÆÌ �ÇÊ ÆÇÆ ÇÊÌÀÇ�ÇÆ�Ä � ��ÇÅ�ÌÊÁ�Ë ËÙÑÑ�ÖÝ ÊÇ��ÊÌ ËÇÍ��Ê�Ë ��� ÖÙ� Ä��ÓÒ Å���ÙÜ � � Å�××Ý �Ö�Ò � Ë��×Ñ� ×� Ø�ÓÒ× �Ü����Ø Ô�Ö�Ó�� ÒÓ�×� Ö�ÔÖÓ�Ù �Ò� Ø�� � ÕÙ�×�Ø�ÓÒ ��ÓÑ�ØÖÝ ÓÒ ×��ÐÐÓÛ Ø�Ñ� ×Ð� �× Ì��×� ÒÓ�×�× �Ò �� �ØØ�ÒÙ�Ø�� �Ý ÓÑÔÙØ�Ò� ��Ö� ØÐÝ �Ò Ø�� �Ü �ÓÖ � ÓÖ �Ü �Ý �ÓÑ��Ò �ÓÖ � � ¬ÐØ�Ö Ø��Ø Û�ÐÐ Ö�ÑÓÚ� Ø�� ÐÓ �Ø�ÓÒ× Ó� Ø�� Ô�Ö�Ó�� ÒÓ�×� Ì�� �ÒÔÙØ �Ò�ÓÖÑ�Ø�ÓÒ �Ò Ø��× �×� �× Ø�� ��× Ö�ÔØ�ÓÒ Ó� Ø�� Ø��ÓÖ�Ø� �Ð � ÕÙ�×�Ø�ÓÒ �× � ÕÙ�×�Ø�ÓÒ× �� ÓÑ� ÑÓÖ� ��Ú�Ö×� Û�Ø� ÒÓÒ ÓÖØ�Ó�ÓÒ�Ð ×ÓÙÖ
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Efficient Coherent Noise Filtering - an Application of Shift-Invariant Wavelet Denoising
Authors L.C. Duval and P.-Y. GalibertC-10 EFFICIENT COHERENT NOISE FILTERING: AN APPLICATION OF SHIFT-INVARIANT WAVELET DENOISING L. C. DUVAL 1 and P.-Y. GALIBERT 2 Abstract 1 IFP 95852 Rueil-Malmaison Cedex France [email protected] 2 CGG 91341 Massy France [email protected] Coherent noise or surface waves filtering represents one of the most complex issues in land seismic data processing. Wavelet based filtering has recently begun to challenge the popular and robust frequencywavenumber (�-� Ü-� Ý) filter. Wavelet filters provide fine time-scale representations and non linear filtering capabilities that yield in some instances better results on dispersive coherence noise. We propose in this work an improvement over the classical
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