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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
41 - 60 of 489 results
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GPR Theory and Simulation in 3D Realistic Media
Authors J. M. Carcione, F. Cavallini and M. SchoenbergThe increasing use of ground-penetrating radar (GPR) for solving a wide range of engineering and environmental problems has been pushed by the application of seismic standard techniques, such as multi-fold coverage and processing.
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Multisource Prestack Depth Migration - an Application of GPR Data
Authors M. Barsotelli-Botelho and I. MuftyThe method of reverse-time migration is widely know for high-quality results as well as extremely high computational colts.
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Filtering of Radargram-Traces with the Wavelet-Transform
Authors C. Seegraef and B. ForkmannGround penetrating radar measurements represent a relatively new, fast and high-resolution investigation method for near surface objects. To explain and to interpret phenomena occurring in nature preliminary investigations with synthetically made radargrams have to be done.
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Influence of Hydrogeologic Properties on the Dielectric Permittivity of Sand Cray Mixtures
Authors T. Heßland, E. Moise and P. SchikowskyPorosity, internal surface area, pore filling, grain size, and temperature have great influence on the velocity of propagation of electromagnetic waves in granular soil. Therefore we investigated these parameters in laboratory to estimate their relevante for field measurement with Ground Penetrating Radar (GPR). Furthermore we verified the applicability of a whole range of mixing formulae which are important for the computation of water content from the propagation vetocity of radar waves.
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Imaging Structures under a Steel-Reinforced Concrete Floor
Authors J. B. U. Haldorsen, D. E. Miller and F. GilbertWe had undertaken a study aimed at assessing the quality of images obtained with ground-penetrating radars (GPR). Using the commercial, impulsive pulseEKKO 1000 from Sensors & Software, and non-standard acquisition geometries, we had collected several 3-D datasets in a natural, suburban environment in Newtown, Connecticut. When approached by the building manager at our Ridgefield research center who needed to break open a floor in one of the workshops for the construction of a new elevator, we thought it a challenging opportunity, particularly considering the steel rebars we expected to find in the floor of the workshop.
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Cavity Identification with GPR Using Variable Offset and Antenna Orientation
Authors A. Helm and U. YaramanciIn GPR, exploration it is of major interest to identify reflector lithology directly using their reflection characteristics. Investigations have been made with simple reflectors especially on cavities in a mine in saliniferous surrounding. The detection of cavities is not only important for mine security but also for eliminating disturbances in the GPR section.
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Verification of Subsurface Pollution Barriers Using Ground-Penetrating Radar
Authors J. B. U. Haldorsen, F. Gilbert, D. E. Miller and L. PellerinDuring August 1997, a project organized by Lawrence Berkeley National Laboratory was carried out on the grounds of Brookhaven National Laboratory. The purpose of the project was to test the feasibility of controlling buried contaminants by injecting colloidal silica (CS) gel to form an impermeable barrier around the contaminants. Geophysical techniques such as ground-penetrating radar (GPR) may be used in an attempt to verify the structural integrity, extent and bulk hydraulic conductivity of a subsurface barrier.
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Induced Polarization Effects in Frequency and Time Domain Electromagnetic Soundings
Authors S. Krylov, N. Bobrov and B. WächterBoth frequency and time domain electromagnetic soundings are widely employed for solving various near-surface geotechnical problems. The experience of field work has shown that the results of soundings often can be distorted by the frequency dispersion of resistivity which is caused by induced polarization (IP).
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Using PRBS-Sequences as Source for TEM-Measurements
By S. L. HelwigThe transient electromagnetic method (TEM) is a well known tool to investigate the subsurface distribution of electrical resistivity
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TEM Measurements in Bolivia - Comparison of Different Fast Interpretation Methods
Authors S. Greinwald, S. Dautel, C. Grisseman and A. HördtA geophysical survey using Audiomagnetotellurics (AMT), Transient-Electromagnetics (TEM) and Induced-Polarisation (IP) measurements was carried out near the former silver mine at Pulacayo, Bolivia, in 1995. The aim of the survey was to support a structural geology investigation of the mineralized volcanic stock. TEM soundings seem to present the most useful information.
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CMP Method Applied to Multichannel Transient Electromagnetic Data
Authors A. Ziolkowski and B. HobbsWe propose a methodology to enable seismic data processing methods to be applied to MTEM data. In particular, horizontal stacking can be applied to common mid-point gathers of MTEM data in the logarithmic-time domain for signal-to-noise enhancement and (in principle) resistivity estimation. In practice, source static corrections must be very precise.
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Analysis of Time-Lapse TEM Data for Underground Gas Storage
More LessNatural gas is an increasingly important energy resource in Europe. Companies are seeking new storage sites, such as depleted reservoirs or deep aquifers. Monitoring of changes in gas volume is crucial to avoid losses and to use the site at its optimum, capacity. The standard method to monitor the gas movements is to drill monitor wells, which are expensive and give information only about the near vicinity of the well. Electromagnetic (EM) methods have the potential to support the monitoring from the surface and to save drilling costs. They are sensitive to changes in electrical conductivity, and thus to movements in the gas/water contact. To demonstrate the feasibility of EM methods to monitor changes in underground gas storage sites, two transient EM surveys were conducted over a gas storage in France. The aim was to use the differences in the data from the two surveys to detect changes in the subsurface.
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Magnetotelluric Investigation in the Polish Western Carpathians
Authors J. Miecznik, E. Jaword, A. Pepel and A. WajdaObjectives of the magnetotelluric survey in the Carpathians (southern Poland) include identification of the structure of the Carpathian orogen and the topography of the crystalline basement as well as prospecting for hydrocarbons.
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A Trial Application of Streaming Potential to Detecting Underground Water Movement while Pumping up
Authors H. Sato, H. Shima and T. ToshiokaWe are researching about the streaming potential for the purpose of detecting groundwater-flow utilizing the electrical potential clistribution generated by watermovement. Sill(1983) theoretically calculated the streaming potential ctistribution, and Ishido and Mizutani (1981) investigated the theoretical basis and carried out experimental studies. At a geothermal area, the streaming potential is used to investigate the geothermal heat-flow. From an engineering point of view, the determination of groundwater-flow or permeability using the streaming potential distribution seems an attractive technique. We investigated the streaming potential in field and laboratory experiments and investigated its nature during water-extraction at a well.
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Effect of Pore Aspect Ratio on the Seismic Wave Attenuation in Porous Rocks
Authors B. Gurevich and J-L. AuriaultSeismic wave attenuation in porous rocks is an important parameter for the characterization of hydrocarbon reservoirs. The two main physical mechanisms of the attenuation in saturated porous media are associated with the viscous forces caused by the so-called global and local fluid flows of the pore fluid, respectively.
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Permeability from Acoustic Impedance and the Characterization of Fracture Flow
More LessIt is becoming increasingly important to provide a better understanding of the mechanisms of fluid flow through low permeability fractured rock systems and to satisfy the ever more sophisticated needs of hydrocarbon exploration and production
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Inversion for the Tensor of Permeability Using Fluid-Injection-Induced Seismic Emission
Authors S. Shapiro, J-J. Royer and P. AudiganeDuring fluid-injection tests in boreholes a spontaneons seismic emission (microearthquakes) can be induced in rocks. We assume that these seismic microevents are due to the perturbation of the porous pressure caused by the fluid injection.
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