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60th EAGE Conference and Exhibition
- Conference date: 08 Jun 1998 - 12 Jun 1998
- Location: Leipzig, Germany
- ISBN: 978-90-73781-09-2
- Published: 08 June 1998
61 - 80 of 489 results
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Controlling Fluid Extraction from Reservoirs by Monitoring Ground Deformation
Authors K. Lehmann and H. -J. KümpelTo assess rock matrix effects from fluid extraction (like subsidence, compaction, pore fluid depletion), numerical modelling is often used. For this purpose, the knowledge of adequate petrohydraulic parameters is essential.
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Rock Physics for Exploration West of Shetlands
Authors J. Bingham, A. Andrea, J. Hook, R. Simm and J. GallagherSummary not available
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A Comparison of Prestack Migration Gathers Formed by Equivalent Offset Migration (EOM) and DMO-PSI
Authors J. C. Bancroft, G. Margrave and H. D. GeigerConventional prestack migration methods that incorporate some form of velocity analysis, use either constant offset sections, or source gathers (shot records). When the velocities are known, these methods should give identical migrated .images. When the velocities are not known, velocity analysis is attempted by applying inverse NMO (INMO) based on arbitrary assumptions of offset, and with the prestack migration gathers formed at CMP locations.
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An Introduction to the Common Reflection Surface Stack
More LessThe success of standaxd seismic reflection imaging routines, such as Prestack Depth Migration or NMO/DMO/stack depends on the required macro-velocity model. Since their Kirchhoff type implementations collect all possible measured reflections events belonging to either a point in the time or in the depth domain they cannot account for the correct shape of the reflector. In contrast, a common-reflection surface (CRS) stack is a selective stack which depends only on the near-surface velocity. The CRS stack provides a new powerful approach to construct simulated zero-offset (ZO) sections from multicoverage reflection data. It accounts for arbitrary reflector shapes and enables us to establish the macro velocity model after the zero-offset simulation.
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Interval Velocities Inversion Using NIP Wave Attributes
Authors J. C. R. Cruz and H. L. MartinsA new inversion procedure to estimate the interval velocities model is presented in this paper. This is based on the search of two normal-incidence point (NIP) wavefront attributes, namely the radius of curvature and the incidente angle. These attributes are determined with help of one coherency analysis, that is applied to a set of seismic traces pertaining to the multicaverage reflection data corresponding to one common-reflection- point, the so-called Common -Reflecting-Element (CRE) gather.
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Three Dimensional Traveltimes Using the Fast Marching Method
Authors M. Popovici and J. SethianA fast, accurate and unconditionally stable 3-D traveltime algorithm is an important tool in seismic imaging. Applications of a robust traveltime computation module are not limited to 3-D Kirchhoff prestack and poststack migration, but also can be used for 3-D velocity analysis, 3-D Kirchoff modeling, 3-D Kirchhoff datuming, and 3-D variable velocity migration to zero-offset.
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Resolution of the 3D Eikonal Equation Parameterized in Celerity in Weak TI Media
By A. PicaEikonal equation solutions are widely used as an approximation of the Green's function in 3D prestack depth migration processing using the Kirchhoff integral method. They represent in many cases an accurate and cost effective way of computing traveltimes. Nevertheless, the increasing size of acquisition surfaces to be modeled, as well as the increasing depths of the required targets, imply that this stage of depth processing, is not negligable at all in global turnaround. This fact is even more critical as this operation has to be iterated several times for image gather analysis used in macro-model construction.
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Prestack Elimination of Complex Multiples - a Gulf of Mexico Example
Authors G. Cambois and A. GuittonThe complexity of salt structures in the Gulf of Mexico imposes the use of prestack depth migration tor subsap imaging. As exploration moves to deeper water, the presence of surface multiples makes subsalt imaging even more difficult. Standard prestack multiple elimination techniques, such as Radon transforms, fall in the presence of complex structures. The surface multiple elimination technique popularized by the DELPHI consortium offers an attractive alternative since it is theoretically independent of subsurface structure.
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Three Dimensional Multiple Moveout Transformation for the Removal of Water Bottom Seismic Multiples
Authors B. M. Hartley, M. G. Lamont and N. F. UrenA two-dimensional wave-field transformation which is useful for pre-conditioning shot records to enhance removal of multiples has been described previously [1]. This wave-field transformation renders water bottom multiple reflections in a shot record into equally spaced horizontal events.
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Non-Wiener Filter, or Sharp Deconvolution in Elimination of Multiples
Authors G. Ryzhikov and M. BiryulinaThe problem of multiple suppression is of interest up to now despite of its long-standing. A new approach for attenuation of multiples in "locally 1-D" environment is suggested, which is illustrated here with well-controlled processing of synthetic data.
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Wave Equation Prediction and Removal of Interbed Multiples
More LessThe succes of multiple suppression for seismic data often hinges on the accuracy with which the multiple behaviour can be predicted. This is especially true for interbed multiples where small details can be essential for distinguishing the multiples from surrounding primaries. In this paper we describe a new wave equation method of predicting interbed multiples from primary events. This scheme can be used to estimate multiples directly from measured data and has been incorporated into a new suppression technique.
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PEG-LEG Attenuation in Ocean Bottom Acquisitions
By R. SoubarasSeveral methods for processing hydrophone and geophone ocean-bottom acquisitions have been proposed in recent years. The aim of this paper is to examine the way in which these methods address the peg-leg attenuation problem, and compare with streamer data peg-leg attenuation methods. The main conclusion is that the peg-leg attenuation problem is basically the same for ocean-bottom as for streamer acquisitions, and that we should take advantage of our experience in peg-leg attenuation of streamer data far ocean-bottom processing.
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Overburden Removal for Marine Walkaway VSP
Authors M. Higgins, C. MacBeth and A. ZiolkowskiSummary not available
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Migration in Transversely Isotropic Media by Cascading Isotropic Operators
By D. RistowIsotropic migration algorithms for seismic data from anisotropic media produce onder certain conditions large position errors for steep reflectors.
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Anisotropy Effects in a Three-Component 3D VSP
Authors G. Rossi and A. VesnaverFractured rocks with a regional trend of faults constitute several hydrocarbon reservoirs. Often, their cracks cannot be observed directly by seismic waves: then, an equivalent medium with an azimuthal anisotropy is the only reliable way for estimating their presence. The crack directions decide the fluid movements in the reservoir: thus, the detection of the anisotropy type allows optimising the depletion wells for oil and gas production.
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