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63rd EAGE Conference & Exhibition
- Conference date: 11 Jun 2001 - 15 Jun 2001
- Location: Amsterdam, Netherlands
- Published: 11 June 2001
121 - 140 of 516 results
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Velocity Anomalies and Depth Conversion - Drilling Success on Nelson Field, Central North Sea
By T. ArmstrongIV-2 VELOCITY ANOMALIES AND DEPTH CONVERSION – DRILLING SUCCESS ON NELSON FIELD CENTRAL NORTH SEA T. ARMSTRONG Summary 1 The Nelson Field overburden appears to be ‘simple’ comprising smooth horizontal or gently-dipping layers overlying a low-relief Top Reservoir structure. In fact a number of velocity anomalies of Quaternary Mio-Pliocene and Lower Eocene age introduce significant complexity via both steep and gradual lateral velocity gradients which need to be constrained for reliable depth conversion. Introduction The Nelson Field lies about 2.5 km SE of the giant Forties Field along the Forties-Montrose Ridge in the central North Sea. Oil is produced from
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An Assessment of the Impact on Depth Uncertainty of Different Velocity Models
Authors N.J. Crabtree, O. Allen, L.J. West and M. BeasleyIV-3 AN ASSESSMENT OF THE IMPACT ON DEPTH UNCERTAINTY OF DIFFERENT VELOCITY MODELS N.J. CRABTREE O. ALLEN L.J. WEST and M. BEASLEY Abstract 1 The problem of assessing the uncertainty of depth predictions calls for a thorough investigation of all valid methods and techniques. A combination of different methods such as interval velocity crossplotting instantaneous velocity curve fitting and kriging can be used to generate an optimum velocity model for time-to-depth conversion. When choosing an optimum velocity model one particular method has to be chosen at the expense of other nearly equivalent methods. A rigorous estimation of uncertainty needs to
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Pre-Stack Depth Migration for Time-to-Depth Conversion - the Ultimate Tool?
Authors C. Hanitzsch, E. Robein and P. SextonIV-4 PRE-STACK DEPTH MIGRATION FOR TIME-TO- DEPTH CONVERSION – THE ULTIMATE TOOL? Introduction The use of seismic data for accurately predicting the depth of a geological horizon remains one of the most difficult and risky tasks in the geophysicist’s job. In this paper we assess the role of Pre-Stack Depth Migration (Pre-SDM) as a depth conversion technique and question whether Pre-SDM can provide us with not only a better focused image of the subsurface but an image that is closer to true depth. There are many ways that the geophysicist can transform seismic data recorded as a function of wave
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Highlights of Deepwater E and P, with Special Emphasis on West Africa
By J. RoelofsenL-01 HIGHLIGHTS OF DEEPWATER E&P WITH SPECIAL EMPHASIS ON WEST AFRICA J. ROELOFSEN IHS ENERGY GROUP PO Box 152 1258 Perly-Geneva Switzerland 1 Introduction Deepwater exploration has been much on the frontpage of E&P news the last couple of years. And the statement of the early nineties that deepwater was the new frontier exploration area has become true with a series of giant oil and gas fields been discovered beyond the 500-meters water depth line. Notwithstanding this success in deepwater exploration the impact of the discovered reserves on the worldwide existing resources is limited. The probabiltiy to find future oil
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Prospecting in the Palaeocene Deep Water Sandstones of the Norwegian North Sea
Authors J.S. Willoughby, A. Van Bockstaele, J. Kristensen and T.H. DaleL-02 PROSPECTING IN THE PALAEOCENE DEEP WATER SANDSTONES OF THE NORWEGIAN NORTH SEA J. S. WILLOUGHBY A. VAN BOCKSTAELE J. KRISTENSEN and T. H. DALE Statoil Grenseveien 21 4035 Stavanger Norway 1 The Tertiary of the Norwegian North Sea is in its Renaissance period. It has been the focus of recent licence rounds and it is actively being explored. This paper will focus on the exploration of the deep-water fans of the Heimdal and Hermod Formations and will consider techniques used to define the presence of trap reservoir and hydrocarbons. It will include a review of the regional setting stratigraphic
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Nuggets Area Deep Marine Turbiditic Fan Complex, Northern North Sea
Authors R.N. Kimber, R. Cooper, M.C.R. Thomas, L.J. Burns, S.D. Harker and P. CornickL-03 NUGGETS AREA DEEP MARINE TURBIDITIC FAN COMPLEX NORTHERN NORTH SEA Abstract 1 R.N KIMBER 1 R. COOPER 1 M.C.R. THOMAS 2 L.J BURNS 1 S.D HARKER 1 and P. CORNICK 3 1 TotalFinaElf Exploration UK PLC 1 Claymore Drive Bridge of Don Aberdeen AB23 8GB UK 2 Adma-Opco 3 PCA Stratigraphic Consultants Ltd The Nuggets area is located between the Alwyn and Frigg Fields in UKCS Quadrant 3 North Sea and comprises four separate dry gas accumulations (Figure 1). The four Nuggets gas structures were discovered between 1972 and 1991 and are called N1 N2 N3 and N4 (operated
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Sub-Seismic Scale Heterogeneity in Sand-Rich Submarine Fans - Application of the 'Multi-System' Approach within the Greater Brae Area (UKCS)
More LessL-06 SUB-SEISMIC SCALE HETEROGENEITY IN SAND-RICH SUBMARINE FANS – APPLICATION OF THE ‘MULTI-SYSTEM’ APPROACH WITHIN THE GREATER BRAE AREA (UKCS) RICHARD HINEY 1 AND ANDREW HURST 2 1 1 PGS Data Processing PGS House Mayfield Road Walton-on-Thames Surrey KT12 5PL UK 2 Abderdeen University The Brae trend located approximately 145 miles (233 km) north-east of Aberdeen on the western edge of the Fladden Ground Spur is dominated by submarine fan sequences deposited against a background sedimentation of hemi-pelagic clay and low density turbidites. Producing intervals range from Jurassic conglomeratic units to Eocene channel sands. Rationale Using extensive well data and
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Seismic Expression of Large-Scale Sand Remobilisation and Injection in Paleogene Reservoirs of the North Sea Basin and Beyonds
Authors M. Huuse, D. Duranti, J. Cartwright, A. Hurst and B. CroninL-07 SEISMIC EXPRESSION OF LARGE-SCALE SAND REMOBILISATION AND INJECTION IN PALEOGENE RESERVOIRS OF THE NORTH SEA BASIN AND BEYOND 1 1 2 2 1 2 2 MADS HUUSE DAVIDE DURANTI JOE CARTWRIGHT ANDREW HURST and BRYAN CRONIN 1 Wales University 2 Aberdeen University Department of Geology & Petroleum Geology King’s College Aberdeen AB24 3UE UK Introduction Clastic intrusions have been studied in outcrop for more than a century but it is less than a decade since large-scale sand remobilisation and injection features were first recognised in seismic data from the Paleogene of the North Sea Central Trough. As even large-scale
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High Resolution Reservoir Characterization in the Deep Water Gulf of Mexico
Authors B. Bankhead, E. Meanley, D. Jordan and G. SchnerkL-08 HIGH RESOLUTION RESERVOIR CHARACTERIZATION IN THE DEEP WATER GULF OF MEXICO B. BANKHEAD E. MEANLEY D. JORDAN and G. SCHNERK Introduction 1 As the industry pushes into deeper water for hydrocarbon exploration the importance of High-Resolution Reservoir Characterization (HRRC) has increased dramatically as project costs often exceed $1.5 billion. HRRC encompasses the 3-dimensional quantitative determination of reservoir limits structure volume heterogeneity and reservoir properties through the detailed integration and continued iteration of petrophysics geology geophysics and reservoir engineering. This iterative and integrated approach results in the development of a reservoir simulation model which will yield better forecasts of field
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Some PS Mode Acquisition Requirements
Authors R.J. Garotta and P.Y. GrangerL-09 SOME PS MODE ACQUISITION REQUIREMENTS ROBERT GAROTTA and PIERRE-YVES GRANGER 1 Compagnie Générale de Géophysique 91341 Massy France Introduction The combination of compressional and PS converted mode data offers promising exploration tools. However the full benefits of this combination can be expected only when comparable resolution is obtained from the two modes at target level. It is currently often observed that PS resolution deteriorates with depth at a faster rate than P resolution. Some of the differences in P or PS propagations and recordings related to asymmetry or anisotropy have been closely investigated and are generally taken into account
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Triple Sensor Wavefield Separation
Authors M. Gidlow and J. SonnierL-10 TRIPLE SENSOR WAVEFIELD SEPARATION Summary 1 A method is described of identifying different wave modes recorded by ocean bottom multi-component detectors. Vertical geophone horizontal geophone and hydrophone data are combined to form filters which when applied to the input wavefields separate the upgoing P-waves upgoing S-wave and downgoing P-waves. Introduction Four component ocean bottom hardware consists of three orthogonal geophones and a hydrophone. This allows for the recording of compressional as well as shear energy. Shear energy mode converted from the compressional energy upon reflection provides additional information about the subsurface. Benefits of mode-converted seismic include: i) the enhanced
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Dispersive Noise Attenuation for Converted Wave Data
By R. SoubarasÄ �ÁËÈ�ÊËÁÎ� ÆÇÁË� �ÌÌ�ÆÍ�ÌÁÇÆ �ÇÊ �ÇÆÎ�ÊÌ�� Ï�Î� ��Ì� ÊÇ��ÊÌ ËÇÍ��Ê�Ë ËÙÑÑ�ÖÝ ��� ÖÙ� Ä��ÓÒ Å���ÙÜ � � Å�××Ý �Ö�Ò � Ì�� ÓÒÚ�ÒØ�ÓÒ�Ð Û�Ý Ó� �ØØ�ÒÙ�Ø�Ò� Ó��Ö�ÒØ ÒÓ�×� �× ØÓ Ù×� ��Ò ¬ÐØ�Ö× Ö�ÑÓÚ�Ò� � ��Ú�Ò Ú�ÐÓ �ØÝ Ö�Ò�� Ì��×� ¬ÐØ�Ö× �ÒÒÓØ �� Ú�ÖÝ ×�Ð� Ø�Ú� ��Ø��Ö �� �Ù×� Ó� �ÒØÖ�×� Ð�Ñ�Ø�Ø�ÓÒ× ÓÖ �� �Ù×� Ø�� Ú�ÐÓ �Ø��× �Ö� ÒÓØ �ÒÓÛÒ �Ü� ØÐÝ �Ò� Ú�ÖÝ �ÖÓÑ ��Ø��Ö ØÓ ��Ø��Ö Ì�� ÔÖÓ �××�Ò� Ó� È Ë ÓÒÚ�ÖØ�� Û�Ú�× �× � �×� Û��Ö� Ø�� ¬ÐØ�Ö× Ù×�� ØÓ �ØØ�ÒÙ�Ø� Ø�� Ó��Ö�ÒØ ÒÓ�×� ��Ú� ØÓ �� ×�Ð� Ø�Ú� ÁÒ Ø��× Ô�Ô�Ö �Ò �Ð�ÓÖ�Ø�Ñ �×
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Converted-Wave Prestack Imaging and Velocity Analysis by Pseudo-Offset Migration
More LessL-12 CONVERTED-WAVE PRESTACK IMAGING AND VELOCITY ANALYSIS BY PSEUDO-OFFSET MIGRATION WEIZHONG WANG and LONG D. PHAM Summary A new technique for converted-wave (Cwave) prestack imaging and velocity analysis is presented. This technique called pseudo-offset migration (POM) differs from equivalent-offset migration (EOM) (Bancroft et al. 1998) in how the migration mapping offset is defined. In this paper we show that POM is less dependent on the initial velocity than EOM and can produce better images and C-wave velocities than P- S DMO plus poststack migration. Introduction Converted-wave processing is more difficult than pure-mode processing. A simple common-conversion-point stack requires an input
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True Amplitude Migration of PS Converted Waves
Authors C. Vanelle and D. Gajewskiin terms of second order spatial derivatives of traveltimes � . Provided that a traveltime curve is smooth and single-valued (the approach is the same for multi-valued traveltimes but the different branches of the traveltime curve have to be treated separately) � can be expanded into a Taylor series corresponding to the paraxial approximation: � � © � � � � � � � (3) � � � � are the slownesses at the source and receiver the matrices and are the � second order derivatives of the traveltime with respect to receiver source and mixed coordinates. and� Vectors and
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Preserved Amplitude Depth Imaging - Application to an OBC Line (Mahogany)
Authors M. Alerini, S. Le Bégat and G. LambaréL-14 PRESERVED AMPLITUDE DEPTH IMAGING – APPLICATION TO AN OBC LINE (MAHOGANY) Abstract 1 We present a first application of our 2D elastic prestack depth processing sequence to an OBC line recorded on the Mahogany field. This sequence is based on ray tracing in smooth velocity models and oriented towards amplitude preservation. Common Image Gathers (CIG) in the angle domain are computed by P-P and P-S migration/inversion using a Vp velocity macro-model obtained by stereotomography and a Vs velocity macro-model deduced from the Vp model by iterative pre-stack depth migrations. Introduction Ocean Bottom Seismology provides an opportunity to improve reservoir
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P-P and P-S Joint Velocity Inversion for Multicomponent Seismic Data
By Y. ZhangL-15 P-P AND P-S JOINT VELOCITY INVERSION FOR MULTICOMPONENT SEISMIC DATA YAOHUI ZHANG 1 PGS Seres Division 738 Highway 6 South Suite 300 Houston TX 77079 USA Abstract A novel and robust method to extract P and S interval velocities from multicomponent seismic data via P-P and P-S joint velocity inversion is presented in this paper. The joint inversion was performed on time migrated data and the estimated initial velocities are decomposed and reconstructed into an invertible form for the derivation of P and S interval velocities. This method is a poststack inversion and is different from conventional velocity inversion
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Anisotropic Analysis and Processing of ALBA 4C OBC Data
Authors H. Dai, X.-Y. Li and M. MacLeodL-16 ANISOTROPIC ANALYSIS AND PROCESSING OF ALBA 4C OBC DATA H. DAI 1 X-Y. LI 1 and M. MACLEOD 2 Summary 1 In this paper we present the anisotropic analysis and processing results from the Alba 3D-4C OBC data. The results show strong evidence of both azimuthal and polar anisotropies. For the azimuthal anisotropy 20ms time-delay was identified from a shallow PS event at PS two-way time 1.4s and the principal direction is about 40 0 from the inline direction. The polar anisotropy estimated from a non-hyperbolic moveout analysis indicates an average 30% converted-wave anisotropy which yields about 2.0% P-wave
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Reservoir Architecture of a Barrier-Type Oil Field Explained by Process-Response Modelling
Authors L.J.H. Alberts and C.R. GeelL-17 RESERVOIR ARCHITECTURE OF A BARRIER- TYPE OIL FIELD EXPLAINED BY PROCESS- RESPONSE MODELLING LUC J.H. ALBERTS and CEES R. GEEL Summary 1 A numerical model that simulates processes responsible for sediment distribution in coastal areas was applied to the Lower Cretaceous Rijn Field West Netherlands Basin. A reconstructed sealevel curve and characterisation of the paleotopography of the region enabled a representative input for the model. Synthetic well logs were generated and compared to the measured well logs and showed generally a good match where the larger differences can be explained by specific geological characteristics that were not accounted for
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Application of Parallel Neural Networks for Reservoir Characterisation while Drilling
Authors A. Bhatt, H.B. Helle and B. UrsinL-18 APPLICATION OF PARALLEL NEURAL NETWORKS FOR RESERVOIR CHARACTERISATION WHILE DRILLING Abstract A new class of networks has been applied to reservoir characterisation using measurements while drilling (MWD) data. The parallel neural network consists of a number of identical networks (experts) trained on identical or overlapping patterns. We demonstrate that this approach is a pragmatic and accurate alternative for converting MWD data to common reservoir parameters such as porosity permeability and water saturation which leads to generation of relative permeability logs for input to real-time reservoir simulation for optimisation of well completion. Parallel Neural Networks Committee machines (CM) belong to
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The Definition of Transmissive-Dominated Hydraulic Units (THU) and Storage-Dominated Hydraulic Units (SHU) and Their Role in the Understanding of Reservoir Dynamics
Authors P.W.M. Corbett, Y. Ellabad and K. MohammedL-19 THE DEFINITION OF TRANSMISSIVE- DOMINATED HYDRAULIC UNITS (THU) AND STORAGE-DOMINATED HYDRAULIC UNITS (SHU) AND THEIR ROLE IN THE UNDERSTANDING OF RESERVOIR DYNAMICS Abstract 1 Two techniques in petrophysics have been combined for the first time to produce a description of the rock that links primary texture through to well test response. The method is proposed as a new approach to dynamic reservoir characterisation and is illustrated for two North African clastic reservoir examples. Introduction PATRICK CORBETT 1 YASIN ELLABAD 1 2 and KHALIFA MOHAMMED 1 3 1 Department of Petroleum Engineering Heriot-Watt University Edinburgh EH14 4AS UK 2 Wintershall
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