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71st EAGE Conference and Exhibition - Workshops and Fieldtrips
- Conference date: 08 Jun 2009 - 11 Jun 2009
- Location: Amsterdam, Netherlands
- ISBN: 978-94-6282-103-3
- Published: 08 June 2009
81 - 100 of 112 results
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Structure and Facies Analysis of a Carbonate Hydrogeothermal Reservoir within the Southern German Molasse Basin
More LessGeothermal energy is an increasing part of the worldwide energy supply. There are three geological provinces in Germany with hydrogeothermal potential: the North German Basin, the Upper Rhine Graben, and the Southern German Molasse Basin. Within the Southern German Molasse Basin the hydrogeothermal aquifer comprises carbonate rocks of the Upper Jurassic which were lowered to a depth of approximately 3500 m.
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The Den Haag Geothermal District Heating Project – 3-D Models for Temperature Prediction.
Authors R. Pechnig, D. Mottaghy, G. Willemsen and E. SimmelinkIn the frame of the „ Den Haag Zuidwest“ geothermal district heating system a deep geothermal installation is projected. The target horizon of the planned doublet is the „ Delft sandstone“, an upper Jurassic sandstone layer, which has been extensively explored for oil- and gas reservoirs in the last century.
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MeProRisk - New methodology for the development of geothermal reservoirs
Authors J. Arnold, R. Pechnig and D. MottaghyMeProRisk is a joint project of five university institutes at RWTH Aachen University, Free University Berlin, and Kiel University. Two partners, namely Geophysica Beratunggesellschaft mbH (Aachen) and RWE Dea AG (Hamburg) present the industrial side. It is funded by the German Ministry of Education and Science (BMBF).
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A Geothermal Site Combined with CO2-storage
Authors D. Gilding, A. Wever and K. -H. WolfFollowing two geothermal projects in Bleiswijk (for glashouses,1700 m depth) and the Hague (6000 houses), students of Delft University, Department of Applied Earth Sciences, started a feasibility study where casing drilling with composite pipe and CO2-injection are combined with the production of geothermal energy. An anticlinal structure is present below the campus, which holds the Jurassic aged Rijswijk and Delft highly permeable sandstone members at a depth between 1.8 and 2.4 km. This member can produce about 150 m3 of water per hour at 75°C. In urban environments, small operational footprints are essential for drilling a production- and a CO2- injection well (Fig.1a). By using new light-weight composite materials for wells with casing drilling technology, only small drilling rigs are required. The composite material is less susceptible to corrosion and enables co-injection of CO2 with the returning water (Wolf et al. 2007).
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The use of locally coherent events in seismic processing: a state of the art
By G. LambaréSeismic imaging methods based on the concept of locally coherent event have known a strong expansion in the recent years. In addition to the fact that locally coherent events fit our intuitive understanding of seismic traces, this expansion must be put on the theoretical and numerical progresses of high frequency asymptotics in seismic imaging. Indeed geometrical optics offers a beautiful frame for the analysis of locally coherent events, which can be described by various kinematic and dynamic parameters. Among them, the travel time and the slopes of the event in the gather of traces have a direct connection with the classical ray parameters, and tomographic and migration methods can be based on. In the present paper I present the basis of these methods and review the recent progresses.
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Parameterization, stacking, and inversion of locally coherent events with the Common-Reflection-Surface Stack method
By J. MannThe Common-Reflection-Surface Stack method relies on the presence of locally coherent reflection events in the seismic prestack data. Using a secondorder traveltime approximation in an automated coherence analysis, such events are locally characterized by means of so-called kinematic wavefield attributes. The most important purpose of these attributes is velocity model building within as well as beyond the second-order assumptions inherent to the CRS approach.
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Macro-model independent migration to zero offset (CRS-MZO)
Authors G. Garabito, W. Söllner and J. C. CruzThe Common-Reflection-Surface (CRS) stack is a well-established time imaging method that provides high quality stacks of three or two-dimensional seismic data and also important kinematic wavefield attributes as a byproduct. In the present work, we build from the CRS a common diffraction surface (CDS) and migrate multicoverage seismic data to zero-offset. The migration to zero offset CRS-MZO operator is defined by a second order (hyperbolic) travel time approximation that depends on two wavefield attributes (or CRS parameters): the emergence angle of the normal ray and the radius of curvature of the normal incidence point (NIP) wave. This parameter estimation is carried out by means of optimization procedures using as objective function the coherence (semblance) of the seismic traces along the CRSMZO operator. The CRS-MZO method is tested using the 2D Marmousi synthetic data and finally applied to 2D land seismic data of the Tacutu Basin (Brazil).
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Fast estimation of CRS parameters using local slopes
Authors L. T. Santos, J. Schleicher, J. C. Costa and A. NovaisThe complete set of CRS parameters can be extracted from seismic data by an application of modern local-slope-extraction techniques. The necessary information about the CRS parameters is contained in the slopes of the common-midpoint and common-offset sections at the central point. As demonstrated by a synthetic data example, the slope extraction is sufficiently robust to allow for derivation of the extracted slope field. This enables the calculation of the CRS parameters from the extracted slopes and their derivatives. In this way, the CRS parameter extraction can be sped up by several orders of magnitude.
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An imaging work flow using locally coherent events - A CRS based approach
Authors M. Baykulov, St. Dümmong and D. GajewskiThe Common Reflection Surface (CRS) stack is a multi-parameter processing approach based on locally coherent reflection events. Best coherency is obtained if the fitted reflection data are hyperbolic within the CRS apertures under consideration. The latter applies to the source receiver aperture and the CMP displacement. Based on the hyperbolic assumption the CRS attributes are determined during the optimisation procedure to best fit reflection events in the data. These attributes are the backbone of the CRS workflow. The CRS attributes are steering the stack, the velocity model building by Normal Incidence Point (NIP) tomography, the multiple suppression, and the enhancement and regularization of pre-stack data. Pre-stack data enhancement and data regularization is performed by so called partial stacks to form CRS supergathers. Partial stacks are essential to remove artefacts caused by adaptive filtering of multiples in pre-stack data. Pre-stack depth migration of CRS supergather leads to CIGs which have an improved S/N and are better suitable to residual move out analysis and quality control than conventional CIGs. Pre-stack depth migrated sections obtained from CRS supergathers display an S/N ratio almost comparable to the CRS stack section.
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Locating VSP Diffracted Arrivals
By M. HumphriesDiffracted arrivals from geological discontinuities in the vicinity of the borehole are often seen in Vertical Seismic Profile (VSP) datasets and appear as locally coherent events. For simple VSP configurations there is not usually sufficient data to migrate the diffractions to a sharp image. Simple location methods often have to be utilised. The use of one micro-seismic processing technique is investigated as a way of locating diffraction sources using a real VSP example.
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Dipscan Tomography
Authors H. Tieman, J. Sherwood, K. Schleicher, K. Sherwood and S. Brandsberg-DahlWe describe a method of tomography that uses dip measurements taken from locally coherent events in surface data in time. The dip measurement needed for tomography is the offset dip, which is measured along the source-receiver azimuth. Following migration of an event, the error in offset dip can be computed, and this input to a tomography program to calculate the slowness field error. Adding this to the input subsurface model results in an updated model. Three iterations of dipscan tomography is needed at the present to generate a reasonably converged model.
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Velocity analysis using OCO rays
More LessOCO rays are lines associated with trajectories described by image points in a simulated common-offset section when several velocity fields are used for offset continuation (OCO) transformation. We present a methodology which makes use of OCO rays to find RMS velocity field using only two common-offset sections, which are referred as take-off and target sections, respectively. The main idea of this approach consists of looking for the best correlation between a selected reflection event in the take-off section and the corresponding one in the target section, being the search carried out along the appropriated OCO rays. We successfully apply the methodology in a deep water field dataset obtaining a geologically consistent time interval velocity model.
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Integrating various seismic data in generalized slope tomography for velocity model improvements
Authors S. Le Bégat, S. A. Petersen and T. HiltonCombining seismic data in a joint processing has several interests as complementary information and constrains on the sub-surface are available. For instance, surface and borehole seismic data integrated in joint tomography lead to intrinsic well-tie of reflection seismic, and allow anisotropy estimation. Joint tomography of reflected and refracted arrivals better determines near-surface models and consequently improves deep imaging. Accounting for reflections, diffractions plus transmissions in cross-hole tomography increases the resolution of velocity models.
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Kinematic Invariants Describinh Locally Coherent Events: An Efficient and Flexible Approach to Non-Linear Tomography
Authors J. -P. Montel, N. DeLaderriere, P. Guillaume, G. Lambaré, T. Prescott, J. -P. Touré, Y. Traonmilin and X. ZhangSlope tomography allows estimating velocity models from locally coherent events. These events can be picked in the prestack depth or time migrated domains, and then de-migrated into the prestack time un-migrated domain, providing what we call kinematic invariants. Kinematic invariants describe locally coherent events by their position and slopes in the unmigrated prestack time domain. Non-linear 3D slope tomography based on the concept of kinematic invariants provides a powerful tool for velocity model building as several iterations of residual move-out picking, prestack depth migration and velocity updates are avoided, unlike other approaches where residual depth errors have to be re-picked several times.
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Taking apart beam migration
By S. H. GrayOver the past decade, a number of beam depth migration methods have emerged. Papers by Sun et al. [2000] on slant-stack Kirchhoff migration and Hill [1990, 2001] on Gaussian beam migration showed the potential of migration methods that combine aspects of Kirchhoff migration with some novel preprocessing. Also during this period, a growing number of workers implemented beam migrations that combine efficiency and imaging fidelity. Unfortunately beam migration is complicated, so a simple interpretation of beam migration, analogous to that of Kirchhoff migration, has been hard to pin down. In this paper, I try to add some intuition to the discussion of beam migration methods. I describe Gaussian beam migration, which is possibly the most complicated of the slant-stack migrations; this makes my task challenging. However, an elementary interpretation of this method is possible, and allows an understanding of the entire family of newly-emerging beam migration techniques.
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Seismic imaging in the curvelet domain: achievements and perspectives
Authors H. Chauris and J. MaFrom a geophysical point of view, curvelets can be seen as the representation of local plane waves. They can be useful for a series of seismic processing tasks, in particular for data denoising or data compression. We discuss if curvelets are well-suited for seismic migration. It appears that the modification of the curvature induced during the wave propagation has to be correctly taken into account. In the case where the maximum wave front curvature is limited, then curvelets can be used to simplify the imaging operators by only using the leading-order terms.
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The Gaussian beam summation method and its applications in geophysics
Authors M. Popov, N. Semtchenok, P. Popov and A. VerdelIn the presentation we describe the mathematical basis of the Gaussian beam summation method and its applications in geophysics that concern the following topics: modelling, migration, inversion and velocity model reconstruction. For each topic we emphasize specific features of the method that lead to advantages in practical applications and demonstrate these for a number of numerical experiments with synthetic benchmark data. With regard to the migration problems, we pay special attention to the difference between the Gaussian beam migration method proposed by N.R. Hill and our Gaussian beam summation method. The numerical results presented here prove that the Gaussian beam summation method can be considered a powerful tool in a variety of geophysical applications.
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Formation of Deep Glacial Incisions During the Elsterian in NW-Europe
More LessMore than 100 year ago German geologists encountered Quaternary deposits, deeply incised into Tertiary formations in the northern part of their country. As, in contrast to the Tertiary units, the incisions contained coarse sands containing good quality ground water these were unique targets for the extraction of drinking water. Although over the last century much information has been collected from boreholes, doubts remained over the mechanism responsible for the formation of the incisions.
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A New Depositional Model for Glacial Sediments in Killiney Bay During the Late Devensian Deglaciation – East Central Ireland
Authors S. Clerc, J. -F. Buoncristiani and E. PortierDuring the last glaciation in northwestern Europe, major studies are consistent with the hypothesis of an ice-stream flowing southward in the Irish Sea Basin, in connection with tributary flows on the eastern part of the Irish Cap (Evans and Cofaigh, 2003; Eyles and McCabe, 1989). During the maximum extent, the ice front reached a position located off the coast of Wales at ca. 22ka BP (Lambeck, 1996; Thomas and Chiverrell, 2007). During deglaciation, sediment deposition processes are predominant, leaving a record of glacially influenced environments. Evidence of such deposits still remains on the coast of the UK and Ireland today. Although these deposits have been studied for many decades, their depositional environment is still under debate and interpretations are evolving, together with new concepts.
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Late Ordovician Jordanian Tunnel Valleys
Authors G. Douillet and J. -F. GhienneThe Hirnantian (latest Ordovician, ~ 444 Ma) glacial advance on the Gondwana shelf succession is documented throughout the Arabian and North African regions with resulting tunnel valleys described for instance in Mauritania (Ghienne et Deynoux 1998) or Libya (Le Heron et al., 2004). Following the work of Abed et al. (1993), Powell et al. (1994) and Turner et al. (2005), field work in Southern Jordan has permitted us to identify nine points with palaeovalley outcrops (fig. 1).
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