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69th EAGE Conference and Exhibition incorporating SPE EUROPEC 2007
- Conference date: 11 Jun 2007 - 14 Jun 2007
- Location: London, UK
- ISBN: 978-90-73781-54-2
- Published: 11 June 2007
41 - 60 of 574 results
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Operational Implementation of Full Azimuth, High Density land Acquisition – 3D Irharen (Algeria)
Authors M. Girard, D. Mougenot, C. Paulet, A. Rhamani, J. J. Griso and Y. BoukhalfaB002 Operational Implementation of Full Azimuth High Density land Acquisition – 3D Irharen (Algeria) M. Girard* (Total SA) D. Mougenot (Sercel) C. Paulet (Total) A. Rhamani (Sonatrach) J.J. Griso (Cepsa) & Y. Boukhalfa (Enageo) SUMMARY Using a square spread of dense receiver stations (25 m) a full azimuth dense 3D survey (730 km² full fold 225) was recorded in 2005-06 over the Irharen gas discovery in Algeria. This land acquisition is representative of the coming trends aimed at improving reservoir illumination and anisotropy detection. If the basic square spread (7 200 channels) was defined from geophysical considerations its practical implementation
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How Radar Shaped the Vibroseis Sweep
Authors P. I. Pecholcs, H. Hussein and R. SaadB003 How Radar Shaped the Vibroseis Sweep P.I. Pecholcs* (Saudi Aramco) H. Hussein (Saudi Aramco) & R. Saad (Saudi Aramco) SUMMARY Attenuation of aliased and often scattered vibroseis source-generated coherent surface wave energy is one of the greatest challenges in seismic exploration on the Arabian Peninsula. To evaluate the signal-toground roll energy ratio for different vibroseis sweep designs and test the claimed benefits of in-field shaped sweep design technology (Trantham 1994) we derived a new hybrid nonlinear frequency modulated chirp signal and directly compared several full-fold nonlinear versus linear vibroseis sweep field experiments. Analysis of single-fold source records demonstrate that
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Enhancing the Low-Frequency Content of Vibroseis Data with Maximum Displacement Sweeps
By C. BagainiB004 Enhancing the Low-Frequency Content of Vibroseis Data with Maximum Displacement Sweeps C. Bagaini* (Schlumberger Cambridge Research) SUMMARY The maximum reaction mass displacement in Vibroseis acquisition limits the energy that can be transmitted to the ground at low frequencies. A method to design the low-frequency end of Vibroseis sweeps that optimally uses the vibrator’s mechanical and hydraulic specifications is proposed. This method which is to a large extent independent of the near-surface elastic properties requires vibrator specifications typically provided by the manufacturers and the desired ground-force power spectral density that depends on the geophysical requirements. The outputs of this sweep
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Acquisition Using Simultaneous Sources
Authors J. Stefani, G. Hampson and E. F. HerkenhoffB006 Acquisition Using Simultaneous Sources J. Stefani* (Chevron Energy Technology Company) G. Hampson (Chevron Energy Technology Company) & E.F. Herkenhoff (Chevron Energy Technology Company) SUMMARY We present a technique in which 2 or more shots are acquired during the time it normally takes to acquire 1 shot. The 2 or more shots are fired in a near simultaneous manner with small random time delays between the component sources. A variety of processing techniques are applied to produce the same seismic images which would have resulted from firing the simultaneous shots separately. These processing techniques rely on coherency of the wavefield
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Do We Reduce Noise by Towing Deeper?
By E. MuyzertB007 Do We Reduce Noise by Towing Deeper? E. Muyzert* (Schlumberger Cambridge Research) SUMMARY Common seismic industry wisdom is that a streamer towed close to the surface is noisier than a deeper streamer. Deep tow techniques such as over/under marine seismic acquisition therefore deliver quiet seismic data. An analysis of over/under marine seismic noise records acquired in moderate good weather showed that the reality is more complicated. It was found that the RMS energy of the full bandwidth of a noise record did not decrease with tow depth contradicting conventional wisdom. It was shown the noise records at frequencies above
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Air–Leak Detection Using Frequency Domain Deconvolution
Authors A. J. Day, S. Hegna, G. Parkes and N. TurnbullB008 Air–Leak Detection Using Frequency Domain Deconvolution A.J. Day* (PGS Geophysical AS) S. Hegna (PGS Geophysical AS) G. Parkes (PGS Geophysical AS) & N. Turnbull (PGS Geophysical AS) SUMMARY Air-leaks in marine seismic sources are known to have a detrimental effect on the source signature and they are therefore not tolerated during production. If an air-leak is detected acquisition must cease whilst the fault is rectified leading to costly “downtime”. A method for detecting air-leaks has been developed that makes use of signatures recorded by near-field hydrophones positioned near each gun in an array. The complex spectrum of each trace
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Time Variant Coloured Inversion and Spectral Blueing
By J. P. NeepB009 Time Variant Coloured Inversion and Spectral Blueing J.P. Neep* (BP Exploration Operating Company Ltd.) SUMMARY Seismic reservoir characterisation can be enhanced by applying two post-stack processes to the seismic data: coloured inversion to invert to relative acoustic impedance and spectral blueing to enhance seismic resolution. Both these methods make the assumption that the seismic spectrum does not change in the time window of interest. However attenuation in the earth results in a reducing seismic bandwidth with twoway time so for interpretation of large time windows this constant bandwidth assumption fails. The use of a single operator will then give
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Demystifying Tight–Gas Reservoirs Using Multi–Scale Seismic Data
Authors M. W. Roth, J. Shemeta and T. DavisB010 Demystifying Tight–Gas Reservoirs Using Multi– Scale Seismic Data M.W. Roth* (Transform Software & Services Inc.) J. Shemeta (Pinnacle Technologies) & T. Davis (Colorado School of Mines) SUMMARY Low permeability fluvial reservoirs in the US Rocky Mountain region are estimated to hold nearly 7000 tcf of gas reserves (DOE 2003). In a typical reservoir several hundred feet of stacked sands are gas charged with natural and induced fractures being essential for economic gas production. While “traditional” seismic data is useful for identifying major geologic interfaces and faults the thin and complex nature of these channel sands are typically below seismic
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Indications for Pressure Release from Zechstein Rafts during Late Kimmerian - Implications for Reducing Drilling Risks
More LessB011 Indications for Pressure Release from Zechstein Rafts during Late Kimmerian - Implications for Reducing Drilling Risks J.H. Ligtenberg* (NAM B.V. - Nederlandse Aardolie Maatschappij) SUMMARY Newly acquired 3D seismic data has revealed details that provide additional information to better understand the Late Kimmerian tectonic phase. Within the study area fluid migration pathways were observed at specific locations. Their occurence location and extend suggest a direct relation with this major tectonic event. In addition a direct correlation appears to exist with Zechstein rafts and deep-seated (reactivated) faults and fault intersections. These fluid migration paths are interpreted to indicate pressure release
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RGB Visualisation Based Delineation of Geological Elements from Volumetric Spectral Decomposition of 3D Seismic Data
Authors S. J. Purves, J. Henderson and C. LeppardB012 RGB Visualisation Based Delineation of Geological Elements from Volumetric Spectral Decomposition of 3D Seismic Data S.J. Purves* (Foster Findlay Associates) J. Henderson (Foster Findlay Associates) & C. Leppard (Hydro) SUMMARY The paper describes a novel set of multi-channel RGB 3D visualisation and GeoBody detection and delineation techniques that form the basis of a true spectral decomposition based volume interpretation workflow developed as part of a research and development collaboration between ffA and Hydro. EAGE 69 th Conference & Exhibition — London UK 11 - 14 June 2007 Introduction The spectral content of recorded seismic data is dependent on the
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Dip, Azimuth and Fault – Volume Extraction and Visualization
Authors A. Alam and J. D. TaylorB013 Dip Azimuth and Fault – Volume Extraction and Visualization A. Alam* (Prime Geoscience Corporation) & J.D. Taylor (Prime Geoscience Corporation) SUMMARY We present an automatic method to estimate dip azimuth and fault continuously in a 3D seismic volume. Spectral decomposition methods provide time-continuous phase spectrum at each trace. Laterally continuous local phase surface at a fixed time indicates a reflector. The surface gradient divided by frequency and averaged over high signal-to-noise ratio frequency bands provides an estimate of time-dip and azimuth. In contrast a discontinuous local time-dip/azimuth indicates a point on a fault conflicting dips interference or noise. Inter-linked
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Automated Horizon and Geobody Extraction Using 3D Seismic Waveform Sequences
Authors H. G. Borgos, O. Gramstad, G. V. Dahl, P. Le Guern, L. Sonneland and J. F. RosalbaB014 Automated Horizon and Geobody Extraction Using 3D Seismic Waveform Sequences H.G. Borgos* (Schlumberger) O. Gramstad (Schlumberger) G.V. Dahl (Schlumberger) P. Le Guern (Schlumberger) L. Sonneland (Schlumberger) & J.F. Rosalba (Petrobras) SUMMARY A methodology for automated 3D interpretation is presented. Sequences of horizons (seismic events) are constructed from pre-computed horizon primitives. These horizon primitives are subsequently used to generate geobodies. Classification techniques can be applied to automatically group seismic events into classes of similar seismic waveform when performing seismic interpretation as described by Borgos et al. (2003). In this work we describe how the classification approach can be used to
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Geological Process Controlled Interpretation Based on 3D Wheeler Diagram Generation
Authors E. M. Monsen, H. G. Borgos, P. Le Guern and L. SonnelandB015 Geological Process Controlled Interpretation Based on 3D Wheeler Diagram Generation E.M. Monsen* (Schlumberger) H.G. Borgos (Schlumberger) P. Le Guern (Schlumberger) & L. Sonneland (Schlumberger) SUMMARY The techniques of a new seismic stratigraphic interpretation paradigm are presented whereby geology is made explicit and is brought into the interpretation process through interactive use of an automatically generated 3D Wheeler diagram. The Wheeler diagram explicitly captures the geological context throughout the interpretation process and provides a great tool for fast QC and data understanding. EAGE 69 th Conference & Exhibition — London UK 11 - 14 June 2007 Introduction Chronostratigraphy is the
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Complex Volumic Seismic Interpretation by New Geobodies Extraction Strategy
Authors F. Pivot, G. Dupuy, S. Gillon and J. N. FerryB016 Complex Volumic Seismic Interpretation by New Geobodies Extraction Strategy F. Pivot* (Total E&P Angola) G. Dupuy (Total S.A.) S. Gillon (Total S.A.) & J.N. Ferry (Total E&P Angola) SUMMARY In this paper we present how new triangulation and propagation algorithms are combined in order to extract relevant and precise geobodies on large lithoseismic cubes. Combined with 3D vizualisation and edition facilities it opens a new way of screening specific geological features of any type in 3D and to obtain triangulated envelopes suited for prospect definition volumetric computations wellbore design and reservoir model construction. Such an approach is illustrated on
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Polarisation Analysis of Ocean Bottom 3C Sensor Data
Authors B. Olofsson and C. MassacandB017 Polarisation Analysis of Ocean Bottom 3C Sensor Data B. Olofsson* (Multiwave Geophysical Company member of CGG group) & C. Massacand (Multiwave Geophysical Company member of CGG group) SUMMARY We analyse seismic polarisation of direct and reflected PS arrivals on multi-component ocean bottom (OB) data by mapping vector fidelity as a function of azimuth and angle of incidence at the seabed. We compare data from a cable system with data from nodes as well as buried and unburied cable sensors. As expected nodes show overall best vector fidelity. For OB cable data on the other hand buried sensors show significantly
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Multicomponent Velocity Analysis with Quaternions
Authors A. Grandi, A. Mazzotti and E. StucchiB018 Multicomponent Velocity Analysis with Quaternions A. Grandi* (University of Pisa presently in Total E&P UK Ltd) A. Mazzotti (University of Pisa) & E. Stucchi (University of Milano) SUMMARY Multicomponent seismic data are acquired by orthogonal geophones that record a vectorial wavefield. Since the single component recordings are not independent the processing and in particular the velocity analysis should be performed jointly for all the components. A way to perform vectorial processing is to exploit quaternions hyper-complex numbers that for their very nature are apt to represent multidimensional data. As an application we show the quaternion velocity analysis for an
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Clair 3D/4C – Demonstrating the Value in Reprocessing 3D Multicomponent Surveys
Authors M. Aitchison, A. Ashby, A. Dawson, M. Ibram, J. McGarrity, C. McKenzie and S. FowlerB019 Clair 3D/4C – Demonstrating the Value in Reprocessing 3D Multicomponent Surveys A. Ashby (WesternGeco) M. Aitchison* (WesternGeco) A. Dawson (WesternGeco) M. Ibram (BP) J. McGarrity (BP) C. McKenzie (BP) & S. Fowler (BP) SUMMARY The Clair field is located 75km west of Shetland and covers an area of 220km2. In 2002 a 3D multicomponent survey was acquired as a result of a successful multi-azimuth 2D test in 2000. The objective was to use wide azimuth OBC data to improve demultiple imaging and to utilise the potential of converted wave (PS) imaging to improve the understanding of fractures in the
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Grane - Converted Wave Imaging for Well Planning
Authors J. P. Fjellanger, F. Bøen and K. J. RønningB020 Grane - Converted Wave Imaging for Well Planning J.P. Fjellanger* (Hydro Oil & Energy) F. Bøen (Hydro Oil & Energy) & K.J. Rønning (Hydro Oil & Energy) SUMMARY The Grane reservoir is difficult to image with ordinary pressure wave (PP) seismic data. In 2001 Hydro acquired a 3D multi-component (4C) survey with ocean bottom cables in the north of the field. A new 4C survey was shot in the south in 2003. The two surveys together cover the whole Grane field. Converted wave data (PS) has proven to give a much better definition of the reservoir sand on Grane
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Anisotropic PP and PSv Prestack Depth Imaging of 4C Data, Pamberi, Offshore Trinidad
Authors T. D. Johns, C. Vito and R. SarmientoB021 Anisotropic PP and PSv Prestack Depth Imaging of 4C Data Pamberi Offshore Trinidad T.D. Johns* (WesternGeco) C. Vito (WesternGeco) & R. Sarmiento (EOG Resources Inc.) SUMMARY In 2004 EOG Resources acquired an OBC 4C swath survey across the Pamberi-1 well location in the Columbus basin eastern offshore Trinidad. Details of the P- and PSv-wave processing through anisotropic PrSTM were previously described (Johns et al. 2006) in which it was demonstrated there existed a qualitative correlation between derived parameters and attributes from P and Sv anisotropic migration velocities and regional geology. Under the “Future work” section of the previous publication
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Imaging through Gas-Filled Sediments with Land 3C Seismic Data
More LessB022 Imaging through Gas-Filled Sediments with Land 3C Seismic Data Y. Li* (BGP) P. Sun (BGP) D. Tang (BGP) Y. He (BGP) H. Chen (BGP) & Y. Yue (BGP) SUMMARY It has been proved in many 4C OBC cases that gas cloud imaging can be improved with converted wave (Li et al. 2001) but few cases have been demonstrated in land 3-C exploration. This paper shows how multi-component (3-C) land data with dynamite source is used to image sub-gas-cloud sediments in CS gas field China. The conventional P-wave data provides unreliable structural images and the interpretation is dubious in an
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