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64th EAGE Conference & Exhibition
- Conference date: 27 May 2002 - 30 May 2002
- Location: Florence, Italy
- Published: 27 May 2002
1 - 50 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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