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65th EAGE Conference & Exhibition
- Conference date: 02 Jun 2003 - 05 Jun 2003
- Location: Stavanger, Norway
- Published: 02 June 2003
1 - 50 of 487 results
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Lithology and Fluid Prediction in the Impedance Domain
Authors P. A. Connolly, T. L. Redshaw and D. N. WhitcombeSeveral domains have been proposed to analyse the effects of changing lithology and fluid on
seismic data. These include intercept/gradient (Castagna et al 1998), lamda-rho/mu-rho
(Goodway et al 1997) and acoustic impedance/gradient impedance (Whitcombe and Fletcher
2001).
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Multiple attenuation using an apex-shifted Radon transform
Authors N. Hargreaves, R. Wombell and R. Ver WestMultiples from sea-floor scatterers and peg-leg multiples in complex
geology are often resistant to conventional multiple removal
techniques such as Radon demultiple. They have a
complicated moveout behaviour in prestack gathers which can only be
approximately represented by a conventional parabolic or
hyperbolic Radon decomposition.
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Draugen Field – Successful Reservoir Management Using 4D Seismic
Authors K. Guderian, M. Kleemeyer, A. Kjeldstad, S.E. Pettersson and J. RehlingA-01 DRAUGEN FIELD – SUCCESSFUL RESERVOIR MANAGEMENT USING 4D SEISMIC Summary 1 K. GUDERIAN 1 M. KLEEMEYER 1 A. KJELDSTAD 1 S.E. PETTERSSON 1 and J. REHLING 2 1 A/S Norske Shell P.O. Box 40 4098 Tananger Norway 2 Petroleum Development Oman (PDO) formerly AS Norske Shell With the application of the current state-of-the-art technology exploitation from the Draugen Field is estimated to reach a world-class recovery factor of about 66%. Through additional optimisation of reservoir management further realisation of development options and high-end technology applications Draugen is aspiring to further increase the recovery factor to some 75%. The key
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3D Pre-Stack Seismic Modeling of Reservoir Grids for 4D Feasibility and Calibration
Authors S. Toinet, E. Brechet, P. Ruelland and Y. ElouairA-02 3D PRE-STACK SEISMIC MODELING OF RESERVOIR GRIDS FOR 4D FEASIBILITY AND CALIBRATION 1 E. BRECHET 1 S. TOINET 1* P.RUELLAND 1 and Y. ELOUAIR 2 1 TotalFinaElf CSTJF Avenue Larribau Pau France 2 previously TotalFinaElf CSTJF now Statoil Norway Abstract Predicting seismic amplitudes changes according to reservoir simulation results in 3D is not obvious but is required in order to perform realistic 4D feasibilities and to calibrate the 4D seismic interpretation in terms of pressure and saturation changes. We present here a methodology to quickly compute 3D pre-stack seismic cubes in depth and time from reservoir simulation grids and
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4D Seismic for Oil Rim Monitoring
Authors R. Staples, P. Hague, T. Weisenborn and P. AshtonA-03 4D SEISMIC FOR OIL RIM MONITORING Abstract 1 4D or time-lapse seismic methods are now being routinely used throughout Shell to monitor fluid movements in producing fields. In most cases 4D seismic data has been used to track the displacement of a single hydrocarbon phase by displacing water or to measure pressure changes. However the seismic response to fluid movements becomes considerably more complex when three fluid phases are involved. The problem is further complicated in fields with thin oil rims where the seismic response from the gas-oil contact (GOC) interferes with the seismic response from the oil-water contact
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Constraining Geological Models Using 4D Seismic at Ekofisk Field
Authors Y. Yin and J. GuilbotA-04 CONSTRAINING GEOLOGICAL MODELS USING 4D SEISMIC AT EKOFISK FIELD Summary 1 Three geological models have been built at Ekofisk field using a well log compactiondecompaction process to describe porosity changes with time due to chalk compaction. In order to constrain these geomodels using 4D seismic information a 1D modeling workflow has been built to efficiently study the seismic responses to reservoir parameter changes and in particular the compaction of the porous chalk. Different compaction models were considered based on laboratory derived equations and output from the flow simulation. A rock physics model for porous chalk was used to relate
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4D Modelling of OWC Movement in Low NTG Areas of the Nelson Field
Authors C. Macbeth, K.D. Stephen and A. McInallyA-07 4D MODELLING OF OWC MOVEMENT IN LOW NTG AREAS OF THE NELSON FIELD 1 Summary A workflow has been established to build detailed meso-scale geological and reservoir models of turbidite systems from core log and laboratory data from which the 4D seismic response can then be calculated. This is used to investigate oil and water movement in the channel margins and interchannel regions of the Nelson field where poor net-to-gross is known to compromise 4D seismic resolution. The analysis confirms that saturation effects dominate and that the characteristic troughpeak signature in the difference volumes formed by the sweep of
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Quantifying Rise in Gas Water Contact from Time-Lapse Seismic on the Sleipner Øst Field
Authors T. Alsos, R. Tøndel, F. Aanvik and O.A. SolheimA-08 QUANTIFYING RISE IN GAS WATER CONTACT FROM TIME-LAPSE SEISMIC ON THE SLEIPNER ØST FIELD Abstract A methodology for quantifying the rise in the gas water contact from time-lapse seismic data is described. The method is based on time-lapse tuning effects and utilizes a combination between horizon interpretation and seismic attribute analysis. The method is applied at the Sleipner Øst Field on marine seismic data acquired in 1994 and 2002. Introduction 1 The Sleipner Øst Fields are located in the southern part of the North Sea. They are producing from three reservoirs; the Paleocene Ty Formation the Jurassic Hugin Formation
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Modeling by True-Amplitude Demigration and Its Application in Time-Lapse Seismics
More LessA-09 MODELING BY TRUE-AMPLITUDE DEMIGRATION AND ITS APPLICATION IN TIME-LAPSE SEISMICS Summary 1 Seismic forward modeling is a frequently used technique to produce seismic time sections for inhomogeneous earth models and arbitrary measurement configurations. However there exists another method to obtain seismograms based on the imaging process “true-amplitude demigration”. Starting with a model an artificial migrated section is created and subsequently demigrated to obtain a seismic section which is similar (but not identical) to the forward calculated one. This proceeding is called “modeling by demigration” and its application is advantageous in some special seismic imaging problems e.g. in the simulation
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Quantitative Estimation of Compaction and Velocity Changes Using 4D Impedance and Travel Time Changes
Authors J. Stammeijer and M. LandrøA-10 QUANTITATIVE ESTIMATION OF COMPACTION AND VELOCITY CHANGES USING 4D IMPEDANCE AND TRAVEL TIME CHANGES Abstract 1 J. STAMMEIJER 1 and M. LANDRØ 2 1 Shell Expro 1 Altens Farm Road Aberdeen AB12 3FY UK 2 Dep. Of Petroleum Engineering and Appl. Geophysics NTNU For some hydrocarbon reservoirs severe compaction of the reservoir rocks is observed. This compaction is caused by the production and is often associated with changes also for the overburden. Time-lapse seismic data can be used to monitor this compaction process. Since the compaction causes both changes in layer thickness as well as changes in the seismic
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4D Signal Enhancement Using Singular Value Decomposition – OWC Movement on the Nelson Field
Authors F.J.L. Reid, C. Macbeth and A.T. McInallyA-11 4D SIGNAL ENHANCEMENT USING SINGULAR VALUE DECOMPOSITION – OWC MOVEMENT ON THE NELSON FIELD Summary 1 In this paper we present a new method for time-lapse signal enhancement using singular value decomposition. Singular value decomposition is used to separate a 4D signal into its constituent parts: common geology time-lapse response and noise. This signal enhancement technique is used to map out both the original and moved oil-water contact across the Nelson field. The SVD technique allows the oil-water contact to be mapped across regions which would have been missed using traditional methods. The oil-water contact is observed to move
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9C, 4D Seismic Processing for the Weyburn CO2 Flood, Saskatchewan, Canada
Authors R.R. Kendall, R. Winarsky, T.L. Davis and R.D. BensonA-12 9C 4D SEISMIC PROCESSING FOR THE WEYBURN CO2 FLOOD SASKATCHEWAN CANADA Abstract 1 We present a summary of the 9C 4D processing used for the seismic monitoring of a CO2 flood in the Weyburn Field Saskatchewan Canada. The resultant time-lapse anomalies for both the P- and S-wave volumes are coincident with the locations of the CO2 injection patterns. Furthermore the anomalies that we observe are extremely robust and are typically observed far before the final processed sections were produced. That is they are evident on the differenced brute stacks. We believe this is largely due to the similarity of
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Processing of OBC and Surface Seismic Data for Reservoir Monitoring at the Statfjord Field
Authors G. Oexnevad, K. Duffaut, F. Foldal, J. Helgesen, D. Lecerf and M. ThompsonA-13 PROCESSING OF OBC AND SURFACE SEISMIC DATA FOR RESERVOIR MONITORING AT THE STATFJORD FIELD Summary 1 We have investigated how processing can improve repeatability between surface seismic and OBC (P/Z) data from the Statfjord Field with application in seismic monitoring. We first tried post-stack matching of previously processed data sets. This proved sufficient for realistic mapping of production effects. Further improvements in repeatability were obtained by a proper 4D concurrent processing of OBC and surface seismic data. Introduction Seismic data acquired at the sea bottom will play a more important role in future reservoir monitoring. The potential benefits compared
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Discrimination between Real and Artificial Time-Lapse Changes in OBC-Data
Authors J. Spetzler and Ø. KvamA-14 DISCRIMINATION BETWEEN REAL AND ARTIFICIAL TIME-LAPSE CHANGES IN OBC- DATA Abstract 1 JESPER SPETZLER 1 and ØYVINDKVAM 2 1 Dept. of Applied Earth Sciences TU-Delft TheNetherlands 2 Dept. of Petroleum Engineering and Applied Geophysics NTNU Wepresent anew method for time-lapse monitoring of OBC data. The time-lapse monitoring accounts for several important non-repeatability effects which is shown in a synthetic experiment. Introduction Non-repeatability effects (e.g. acquisition differences between two surveys noise and overburden effects) in 4D experiments can easily result in unrealistic time-lapse changes where actually none exists. Before continuing reading try the following exercise; Decide which one of the
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The Case for 4D Monitoring with Sparse OBC
Authors R.W. Calvert and P. WillsA-15 THE CASE FOR 4D MONITORING WITH SPARSE OBC Abstract Introduction We seek a better faster cheaper way of performing 4D seismic monitoring to improve reservoir management. We present the case for sparse OBC surveys as a candidate for this. “Better” would be an ability to detect smaller changes due to production and thus make 4D applicable for more fields and to allow earlier spatial diagnosis of production effects. This increased sensitivity depends upon an ability to produce more repeatable data where the subsurface has not changed so that small differences relate to real subsurface effects. This repeatability depends upon
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Seismic Forward Modeling in a Chalk Reservoir with Permanent Monitoring
By O.J. AskimA-16 SEISMIC FORWARD MODELING IN A CHALK RESERVOIR WITH PERMANENT MONITORING Abstract Advances in the last decade of time-lapse seismic technologies have developed a better understanding of the controlling parameters in seismic imaging repeatability and rock properties. This paper presents the seismic modeling element of a feasibility study for a permanent seabed 4C installation over Valhall a North Sea chalk field. Such a permanent installation allows for ‘acquisition on demand’ whose timing is driven by the dynamic changes in the reservoir. 1 An initial feasibility study addressed whether the expected reservoir depletion and subsequent water flood would generate a detectable
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Andrew Seismic Reservoir Surveillance
Authors R. Trythall, R.S. Parr, J. Wreford and A. SmoutA-17 ANDREW SEISMIC RESERVOIR SURVEILLANCE Overview A 4D (time lapse 3D) seismic survey was acquired in May 2001 across the Andrew field in the UKCS. A weak seismic 4D response was observed which was compared against two contemporaneous time lapse production logs. The close agreement between the results of these complimentary surveillance methods allowed the validity and calibration of the water and gas saturation changes to be tested across the whole field. The production logs provided indications of fluid flow at the wellbore whilst the 4D provided its regional perspective. The application of this method across the whole field has
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Calibration of 4D Seismic Fluid and Lithology Amplitudes over the Arbroath Field
More LessA-18 CALIBRATION OF 4D SEISMIC FLUID AND LITHOLOGY AMPLITUDES OVER THE ARBROATH FIELD 1 Introduction The Arbroath Field is located within UKCS Blocks 22/17 and 22/18 and together with the adjacent producing oil fields Montrose and Arkwright comprise the MonArb group of fields. The main producing horizon of all three fields is the Forties Sandstone lying at approximately 8150 ft TVD SS in the Montrose and Arbroath Fields and 8430 TVD SS in the Arkwright Field. Production of oil from the Montrose Field started in 1976 and decreased to very low levels in 1990. The Arbroath and Arkwright Fields are
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Integrated AVO Reservoir Characterization and Time-Lapse Analysis of the Widuri Field
Authors P.R. Mesdag, R. Van Eykenhof, W.E. Harmony, L. Harvidya, M. Sams and P. Van RielA-19 INTEGRATED AVO RESERVOIR CHARACTERIZATION AND TIME-LAPSE ANALYSIS OF THE WIDURI FIELD Summary 1 Reservoir characterization of the Widuri field offshore SE Sumatra is complicated by complex lithology and difficulties in predicting changes in fluid distribution during production. In 2000 a monitor 3D seismic data set of the Widuri field was acquired and processed to take advantage of seismic AVO effects. The base line 1991 seismic data set was reprocessed in parallel. The primary reason for the monitor data set was to observe the reservoir pressure depletion state around a water-flooding project. Furthermore there was a need to improve the
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Improving Reservoir Understanding Using Time-Lapse Seismic at the Heidrun Field
Authors A-K. Furre, F.R. Munkvold and L.H. NordbyA-20 IMPROVING RESERVOIR UNDERSTANDING USING TIME-LAPSE SEISMIC AT THE HEIDRUN FIELD Abstract 1 A time-lapse repeated seismic survey was last year conducted over the southern part of the Heidrun oil field. The main purpose of the repeated survey was to identify remaining infill drilling targets in the Fangst Group. The results from the seismic monitoring study were together with reservoir simulation results production data repeated logs and other data integrated to generate drainage maps for three reservoir levels. These drainage maps were actively used in planning infill and up-flank drilling locations in Fangst and served as an important tool in
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Oil Field Water Injection – a Large-Scale Water-Rock Experiment – Results and Applications
Authors H. Johansen, B.V. Nystrand, H. Stray, I. Johansen and Ø. DugstadA-21 OIL FIELD WATER INJECTION – A LARGE SCALE WATER-ROCK EXPERIMENT – RESULTS AND APPLICATIONS Summary 1 H. JOHANSEN 1 B.V. NYSTRAND 2 H. STRAY 1 I. JOHANSEN 1 and Ø. DUGSTAD 1 1 Institute for Energy Technology P.O.Box 40 2027 Kjeller Norway EAGE 65th Conference & Exhibition — Stavanger Norway 2 - 5 June 2003 2 A/S Norske Shell Water-rock interaction during sea water injection in the Norne Field Norwegian Sea has been investigated by natural chemical and isotopic tracers. A procedure to identify good breakthrough monitors has been developed. The nature of mineral reactions in the reservoir during
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4D Seismic Response of Primary Production and Waste Injection at the Valhall Field
Authors O. Barkved, K. Buer, K.B. Halleland, R. Kjelstadli, T. Kleppan and T. KristiansenA-22 4D SEISMIC RESPONSE OF PRIMARY PRODUCTION AND WASTE INJECTION AT THE VALHALL FIELD Introduction A new 3D seismic data set was acquired across the Valhall field during the summer of 2002. The presences of strong production induced seismic responses were expected due to the nature of the field and earlier observations. The Valhall reservoir is a highly porous chalk which compacts as the reservoir is depleted. The compaction results in a “hardening” and thickness reduction of the reservoir and subsequent subsidence of the overburden and the seafloor. The new data was processed using a “similar” processing flow as was
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Use of PP and PS Time-Lapse Stacks for Fluid-Pressure Discrimination
Authors A. Stovas, M. Landro and B. ArntsenA-23 USE OF PP AND PS TIME-LAPSE STACKS FOR FLUID-PRESSURE DISCRIMINATION Abstract 1 A complementary method to achieve quantitative information about reservoir property changes during production is to measure shift in two-way traveltime within a given reservoir section. A practical example of how this method can be used to give additional information about pressure and saturation changes in reservoir segment is given in Landrø 2001 Landrø 2002 and Landrø et al. 2003. In this paper we investigate how combined use of time-lapse PP and PS seismic data can be processed and analyzed for the discrimination between pressure and saturation changes.
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Super-Resolution Mapping of Thin Gas Pockets
Authors H.G. Borgos, T. Randen and L. SonnelandA-24 SUPER-RESOLUTION MAPPING OF THIN GAS POCKETS Summary 1 Improved resolution in seismic prospecting implies better resolving power of objects in the subsurface. It is well known that resolution is directly related to the frequency bandwidth of the seismic measurement. Various criteria for the resolving power exist like the Rayleigh criterion [1]. Under certain conditions the resolution can be improved beyond the limits of i.e. the Rayleigh criterion. These conditions can be that additional information about the scene being analyzed is available. Procedures that enable such improved resolution are referred to as super-resolution. We will present a seismic super-resolution procedure
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Modeling of Fluid Effects in Compartmentalized Areas, an Oseberg South Case Study
Authors S.A. Petersen, B.A. Farrelly and B.I. BraathenA-25 MODELING OF FLUID EFFECTS IN COMPARTMENTALIZED AREAS AN OSEBERG SOUTH CASE STUDY 1 S.A. PETERSEN B.A. FARRELLY and B.I. BRAATHEN Norsk Hydro E&P PO Box 7190 N-5020 Bergen Norway Summary In order to evaluate the seismic (or any other physical) response of the subsurface one should be able to combine a model of the matrix with a model of the pore fluid distribution. The task becomes more especially difficult when the matrix distribution reflects a compartmentalization of the subsurface and/or if more fluid regimes are present. A method to construct such several models is presented and applied in a
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Absolute and Relative Gravity Integration for High Precision 4D Reservoir Monitoring
Authors J.M. Brown, T. Chen, T.M. Niebauer, F.J. Klopping, J. Ferguson and J. BradyA-26 ABSOLUTE AND RELATIVE GRAVITY DATA INTEGRATION FOR HIGH PRECISION 4D RESERVOIR MONITORING 1 Based on an estimate 3µGals per 1cm. EAGE 65th Conference & Exhibition — Stavanger Norway 2 - 5 June 2003 1 Abstract In October 2002 BP Exploration Alaska (BPXA) the primary operator of the Prudhoe Bay Oil Field began a large-scale water injection program to counter decreasing pressure on the Prudhoe Bay gas cap. To monitor the progress of the injection program surface gravity measurements will be taken once per year. Reservoir models require total measurement uncertainty to be better than ±10µGals a challenging specification to
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Azimuth Preserved Trace Binning of 4D Seismic Data for Improved Repeatability
Authors X.-P. Li, J. Brittan, S. Harwood and M. WidmaierA-27 AZIMUTH PRESERVED TRACE BINNING OF 4D SEISMIC DATA FOR IMPROVED REPEATABILITY Abstract 1 During the processing of 4D seismic data it is vital to adequately compensate for the nonrepeatability that is a function of acquisition and processing effects. In this paper it is demonstrated that the seismic repeatability can be improved if an azimuth preserved trace binning methodology is implemented between base and monitor survey during the preprocessing stage. This improvement is illustrated using synthetic seismic data generated utilising real navigation data and a model of an isotropic medium. Different types of azimuth based trace binning can be done
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Feasibility of Inverting 3-D FTG Data for Reservoir Monitoring
Authors A. Druzhinin, A. Vasilevsky, J.R. Evans, C.A. Murphy and X-Y. LiA-28 FEASIBILITY OF INVERTING 3-D FTG DATA FOR RESERVOIR MONITORING 1 Abstract Three-Dimensional Full Tensor Gradiometry (3-D FTG) acquisition system takes ultra sensitive realtime measurements of small gravity changes (gradients) caused by density differences in all directions. We have undertaken a numerical examination of the feasibility of using this system for reservoir monitoring. Special gravity modeling and inversion algorithms that can describe and predict the dynamic behavior of a hydrocarbon reservoir have been developed and tested on synthetic FTG data based on realistic 4-D petrophysical models. Our inversion yields estimates of uncertainty in hydrocarbon production data. Results show that the
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New Approach for 4D Processing with OBC Data and Marine Streamer Data
Authors D. Lecerf and T. WeisserA-29 NEW APPROACH FOR 4D PROCESSING WITH OBC DATA AND MARINE STREAMER DATA Abstract 1 The repeatability of marine streamer data and OBC data is generally rather poor because they are acquired in completely different conditions. So can we successfully combine both types of acquisition in order to detect a weak 4D signal? To examine this we introduce the concept of a common seismic cube and partial differences. The common seismic cube represents the invariant geology and is computed with a geostatistical method taking advantage of the redundancy of the seismic data. It shows a better signal to noise ratio
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Seismic Monitoring of the Heidrun, Norne and Midgard Fields Using Steerable Streamers
Authors O. Eiken, H. Aronsen, A.-K. Furre, L. Klefstad, L.H. Nordby, B. Osdal and M. SkaarA-30 SEISMIC MONITORING OF THE HEIDRUN NORNE AND MIDGARD FIELDS USING STEERABLE STREAMERS Abstract 1 Seismic reservoir monitoring has considerable unrealised potential if higher repeatability can be obtained. Today’s towed streamer systems impose basic limitations on repeatability as streamer feather is difficult to repeat. Horizontally steerable streamers can potentially make repeated streamer positions possible. During the 2001 summer season time-lapse data were acquired over three producing fields in the Norwegian Sea using the new technology. We show in this paper some results of these surveys. Introduction Several 4D success stories have been reported but there are also a number of
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Detection of Saturation Changes in a Turbidite Sand by 4D AVOA
Authors A. Shams and C. MacBethA-31 DETECTION OF SATURATION CHANGES IN A TURBIDITE SAND BY 4D AVOA Summary 1 A seismic data processing methodology is developed on the basis of parallelized restricted offset and azimuth pre-stack processing (PROAP) for P-wave OBC time-lapse data. It is designed to preserve the directional signature cross-equalize datasets and generate a suitable input to a filter that separates seismic anisotropy from the static and isotropic ‘geological’ response. Application of this procedure reveals discrete time-lapse anisotropy anomalies in a turbidite sand body. These anomalies change intensity during production with their position and orientation coinciding with the highest net-to-gross sands. The anomalies
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Spectral Decomposition Provides Rapid Screening Tool for Gas Potential in the Norwegian Sea
Authors R.H. Leadholm, T.J. Austin and P.F. OstendorfA-33 SPECTRAL DECOMPOSITION PROVIDES RAPID SCREENING TOOL FOR GAS POTENTIAL IN THE NORWEGIAN SEA 1 R.H. LEADHOLM T.J. AUSTIN and P.F. OSTENDORF ConocoPhillips Norge PO Box 220 N-4098 Tananger Norway EAGE 65th Conference & Exhibition — Stavanger Norway 2 - 5 June 2003 Summary Investigation of 3D data sets over two deep water gas accumulations several dry tests and various undrilled prospects in the Vøring Basin of the Norwegian Sea shows that spectral decomposition phase and amplitude spectra can be used to define gas accumulations. This technique provides a rapid screening methodology and compliments the more traditional utilization of spectral
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Havsule – Exploration in Deep Water Offshore Norway
Authors K.J. Hansch, J.R. Berry and J.J. DoorenbosA-34 HAVSULE – EXPLORATION IN DEEP WATER OFFSHORE NORWAY 1 K.J. HANSCH J.R. BERRY and J.J. DOORENBOS BP Norge Godesetdalen 8 4065 Stavanger Norway The Havsule licence (PL254) was seen as one of the most interesting areas in the Norwegian 16 th licence round. Four licence blocks covering an area of 1800 km 2 were awarded in May 2000 to a consortium of BP Norge Norske Conoco (now ConocoPhillips) SDFI (now Petoro) and TotalFinaElf. BP was assigned operatorship. The licence is located in the Møre basin offshore Mid Norway with an average water depth of about 1500 m. In the
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Identification of Reservoir Rock with Lamé Parameters – An Atlantic Canada Case History
By R. TonnA-35 IDENTIFICATION OF RESERVOIR ROCK WITH LAMÉ PARAMETERS – AN ATLANTIC CANADA CASE HISTORY Abstract Figure 1: EnCana’s landposition in Newfoundland EAGE 65th Conference & Exhibition — Stavanger Norway 2 - 5 June 2003 1 RAINER TONN EnCana Corporation 150 9 th Avenue S.W. P.O. Box 2850 Calgary Alberta T2P 2S5 Canada Summary: Lamé parameters allow the identification of reservoir rock and fluids (Goodway et al.1999 Goodway 2001). This case study demonstrates how λρ and µρ inverted from 3D marine seismic made it possible to classify reservoir rock in an exploration prospect offshore Newfoundland Canada. The analysis of crossplots discriminates
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Challenges in Deep Offshore Imaging, West Africa
Authors C. Lafond, H. Houllevigue, Y. Kerdraon, J.F. Riou, M. Bridson and I. JonesA-36 CHALLENGES IN DEEP OFFSHORE IMAGING WEST AFRICA Abstract 1 The deep offshore of the Gulf of Guinea is a challenge to seismic processing and imaging techniques due to the complexity of the salt body structures and the omnipresence of mode conversions that mask the primary signal. Even though true (Kirchhoff) prestack time migration can recover the top of salt and wide sedimentary basins (not salt covered) it fails elsewhere. We show that wave equation 3D PreSDM is necessary to properly image target sedimentary reflectors in between and below salt domes compared to Kirchhoff 3D PSDM. However this is true
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3-D Prestack Depth Migration and Illumination Analysis - A Case Study from Offshore Norway
Authors C. Gerea, O. Riise, F. Assouline and M. RhodesA-37 3-D PRESTACK DEPTH MIGRATION AND ILLUMINATION ANALYSIS - A CASE STUDY FROM OFFSHORE NORWAY Abstract 1 We present a 3-D prestack depth migration case study from Halten area offshore Norway. Although the geological structure is not very complex we apply advanced migration algorithms to yield accurate seismic images in terms of focusing and positioning and valuable reflection-point gathers for amplitude analysis. The aim of this study is two-fold; to improve the quality of seismic image of the main fault/reservoir segments towards better positioning of production wells and to preserve amplitudes for enhanced mapping of reservoir sands. Advanced 3-D prestack
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Amplitude Brights and Hydrocarbon Occurrence in License PL128, Offshore Mid-Norway
Authors G. Richardsen, K.O. Hartvigsen, F. Karlsen, L. Michelsen, J.O. Hansen and G.R. AhmadiA-38 AMPLITUDE BRIGHTS AND HYDROCARBON OCCURRENCE IN LICENSE PL128 OFFSHORE MID-NORWAY Introduction 1 License PL128 is located on northern Dønna Terrace between the Nordland Ridge and the Træna Basin offshore mid-Norway. Eleven exploration wells have been drilled in the license between 1986 and 2002. Exploration has been successful with discovery of the Norne (1992) Svale (2000) Falk (2002) and Stær (2002) fields. Two additional exploration wells will be drilled during first half of 2003. Within the license area there is a correlation between amplitude brights on top reservoir level and oil discoveries. This relationship has to some extent been used
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Risking Sediment Acces and Charge – Structural and Basin Modelling, Norwegian North Sea
Authors E. Thompson, S. Jones, R. Satter, S. Wigger, N. McCormak and P. GriffithsA-39 RISKING SEDIMENT ACCESS AND CHARGE – STRUCTURAL AND BASIN MODELLING NORWEGIAN NORTH SEA Summary 1 A Norwegian Sea prospect was assessed for risk due to charge and reservoir presence. The prospect was identified by seismic attribute analysis and supporting evidence was sought from modelling. The impact on prospect viability of the sediment access and charge probabilities was examined. It was found that although modelling showed the sediment access to the area was possible the model did not identify known accumulations to the north and was therefore unreliable in this area. The charge modelling accurately identified known reserves to the
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The Importance of Wide Azimuth in Imaging
Authors B. Arntsen and M. ThompsonA-40 THE IMPORTANCE OF WIDE AZIMUTH IN IMAGING 1 B. ARNTSEN and M. THOMPSON Statoil Research Centre Postuttak N-7005Trondheim Norway Summary Comparing 3D depth migrated streamer data and 3D depth migrated OBC data from the same area it is demonstrated that the better quality of OBC data is related to the relatively wider azimuths used in the OBC data acquisition geometry. Introduction The benefits of wide azimuth acquisition geometries have been recognized for a long time in land seismics (Cordsen and Galbraith 2002). Offshore true 3D OBC data has recently become available and the importance of better azimuth coverage both
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Competence and Technology Needs for the E&P Business
By B. NylandB-01 COMPETENCE AND TECHNOLOGY NEEDS IN THE E & P BUSINESS 1 The paper will discuss the changes the use of technology in the E & P business has experienced during the last 10 – 15 years and the causes this has had on competence needs the interaction between different technical subjects and the changes in the working processes. The statement is that the E & P business has become a digital business and how is this being handled both in the industry but also in the academia. What has been achieved during these years and is there something that
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University Curricula and Industry Needs
More LessB-02 UNIVERSITY CURRICULA AND INDUSTRIAL NEEDS 1 The talk with consider the issues that must be addressed by university staff when designing geoscience and engineering course curricula. First and foremost we ignore at our peril the simple fact that our customer is the student. Plausible arguments are sometimes presented for a return to basics; more on classical mechanics for example. However the danger of customers voting negatively with their feet is a very real constraint on the balance and content of course curricula. The customer also expects and assumes that her/his employability will have been increased by studying the course
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E-Learning in Geosciences
More LessB-03 MAKING E-LEARNING WORK – EXAMPLES OF PRODUCTS DEVELOPED BY STATOIL AND NORWEGIAN ACADEMIA Abstract 1 Learning used to be synonymous with attending a formal course or a conference. Nowadays we would also include learning-on-demand and informal learning anytime and anywhere hence the popular term “life-long learning”. Among other things this has been made possible by computers the Internet and the emergence of “e-learning” believed by many to be the great new market of the Internet age. In academia e-learning is usually taken to refer to courses available online with content provided in digital format. However a company employee may
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Technical Skill Assessment – Measuring Staff Capabilities and Optimizing Training Investments
Authors J.D. Johnsen and M. LaPrea-BigottB-06 TECHNICAL SKILL ASSESSMENT – MEASURING STAFF CAPABILITIES AND OPTIMIZING TRAINING INVESTMENTS 1 The value of E&P technology applications can only be realized when technical staff has the skills and knowledge to apply the technology. Significant challenges for E&P companies and vendors today are to deliver focused training for staff in relevant technology applications and to understand the breadth depth and location of technical expertise within their companies. An important yet simple tool to help meet these challenges is rigorous skill or competency assessment. Many companies today (e.g. Shell BP) have implemented skill assessment and are using results to add
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Experience with Generalized-Screen Methods in Wave Equation Migration
Authors C. Notfors, Y. Zhang, Y. Xie and G. ZhangB-09 EXPERIENCE WITH GENERALIZED-SCREEN METHODS IN WAVE EQUATION MIGRATION Summary We present a stable least squares optimized generalized-screen (GS) formula for migration. Theoretical analysis and numerical examples show that our GS method has potential to provide high quality wave equation migration results. It removes splitting errors suppresses numerical dispersion and images steeply dipping reflectors. However when large lateral velocity variations are present the required normalization operator appears to degenerate image quality. Hence improving the normalization method or seeking a more stable algorithm is required for its practical use. Introduction Finite-difference migration based on one-way wave extrapolation (Claerbout 1985) automatically handles
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Angle Gathers for Shot-Record Migration by Local Harmonic Decomposition
By R. SoubarasB-10 ANGLE GATHERS FOR SHOT-RECORD MIGRATION BY LOCAL HARMONIC DECOMPOSITION 1 Summary EAGE 65th Conference & Exhibition — Stavanger Norway 2 - 5 June 2003 ROBERT SOUBARAS CGG 1 rue Léon Migaux 91341 Massy France It is now recognized that shot-record wave-equation migration is the best method for imaging in complex media. However it is also recognized that producing one output image is not enough. Velocity analysis can only be done when a gather is produced as well as AVO analysis or multiple attenuation. This paper starts by describing the local harmonic decomposition: it is an efficient algorithm which can
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One Way vs Two Way Wave Equation Imaging – Is Two-Way Worth It?
Authors J.B. Bednar, K. Yoon, C. Shin and L. LinesB-11 ONE WAY VS TWO WAY WAVE EQUATION IMAGING – IS TWO-WAY WORTH IT? 1 KWANGJIN YOON 1 CHANGSOO SHIN 1 J. BEE BEDNAR 2 and LARRY LINES 3 Abstract 1 Seoul National University Seoul Korea 2 Core Laboratories Houston Texas U.S.A. 3 University of Calgary Calgary Alberta Ca Current production-grade-wave-equation migration technology is almost totally based on one-way methods. These methods are typically derived through an asymptotic approximation of the square root of a one-way propagator derived by factoriaztion of some form of wave equation. Primary reasons for the dominance of one-way approaches are most certainly the relative ease
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Beam-Wave Migration
Authors S. Brandsberg-Dahl and J.T. EtgenB-12 BEAM-WAVE MIGRATION Summary 1 We present a hybrid beam/wavefield migration scheme that overcomes the dip limitation in conventional downward continuation schemes. The resulting migration operators are not limited to downward propagating waves only and in contrast to ray tracing methods they contain the full waveform in areas with large/sharp velocity contrasts. Introduction S. BRANDSBERG-DAHL and J. T. ETGEN BP America Inc. 200 Westlake Park Blvd Houston TX 77079 USA Downward continuation wavefield migration has gained in popularity in recent years and has proven to be an accurate and reasonably stable method for imaging seismic data in complex geology. There
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Delayed-Shot 3-D Prestack Depth Migration
Authors J. Sun, Y. Zhang, C. Notfors, S. Gray, L. Chernis and J. YoungB-13 DELAYED-SHOT 3-D PRESTACK DEPTH MIGRATION YU ZHANG 1 JAMES SUN 1 CARL NOTFORS 2 SAM GRAY 3 LEON CHERNIS 1 and JERRY YOUNG 1 1 Veritas DGC Inc. 10300 Town Park Drive Houston TX 77072 USA Summary We present a formulation for delayed-shot migration of marine data in 2-D (plane-wave sources) and in 3-D (linear sources and planar sources). We present speedup factors for these delayedshot migrations over common-shot migration and we discuss some sampling theory issues associated with the formation of delayed-shot records. On both synthetic and real data examples delayed-shot migration has produced images comparable to those
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VSP Salt Flank Imaging through Wavefield Continuation
Authors S. Brandsberg-Dahl, J.P. Van Gestel, J.T. Etgen and B. HornbyB-14 VSP SALT FLANK IMAGING THROUGH WAVEFIELD CONTINUATION Summary We present a method for imaging steeply dipping features such as salt flank by wavefield migration with horizontal propagation. By literally turning a standard shot record migration scheme on its side we ensure that the horizontally propagating waves are properly treated enabling us to image steeply dipping salt flanks. Introduction 1 Sedimentary layers terminating against salt are a common reservoir structure in many hydrocarbon regions around the world. When mapping the closure of such reservoirs both in the prospect evaluation phase and during development and production knowing the location of the
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Limited Frequency Migration with Interpolation
By J.B. BednarB-15 LIMITED FREQUENCY MIGRATION WITH INTERPOLATION 1 Abstract EAGE 65th Conference & Exhibition — Stavanger Norway 2 - 5 June 2003 J. BEE BEDNAR Core Laboratories 2316 Windfern Houston TX 77040 USA Zero-offset migration/inversion of single-frequency data produces asubsurface image with spatialwavenumbersconfinedtoanEwaldspheredefinedbythedouble-square-rootdispersion relation. Fornon-zero-offsetdata theEwaldspherebecomesanEwalddoughnut. Asaresult a single frequency images avolume of wave-numbers. This fact can be exploited to substantially reduce the number of frequencies needed to accurately map subsurface reflectors. This paper investigates a simple recipe for calculating a sparse set of frequencies for use in frequency-slice migration algorithms. While the migration process is unaltered the smaller set of
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