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54th EAEG Meeting
- Conference date: 01 Jun 1992 - 05 Jun 1992
- Location: Paris, France
- ISBN: 978-90-73781-04-7
- Published: 01 June 1992
381 - 400 of 405 results
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The modern approach to 2D land seismic acquisition
Authors N. A. Hempstead and A. J. WarrThe essence of a successful initiation and subsequent implementation of a seismic survey is first to define the objectives of the survey as clearly as possible, then to establish what physical constraints will be imposed by terrain, ecology, culture, governmental and other regulations, then to select field equipment and parameters and processing approaches to provide a product which will satisfy the interpretational objectives.
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Siganture measurements on marine seismic sources
More LessThe type of seismic source used in a seismic survey is very important. Depending on the aim of the survey, a choice is made which type of source will be used. Other circumstances also have their influence on what type of source will be used (cost, availability, logistic problems, etc). One of the factors that controls seismic resolution is the shape of the source wavelet. Broad band wavelets can lead to short wavelets in time which in turn lead to a high resolution in time .
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Code of practice in geophysics - session 1: recommendations for quality assurance for the supply of geophysical services
Authors A. Bouvier and R. LagabrielleQuality, "a set of properties and characteristics belonging to a product or a service which endow it with the aptitude to satisfy expressed or implicit requirements" , is of major importante for modern economies.
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Code of practice in geophysics - session 2: guide to the suitability of geophysical methods and techniques to applications relating to the surface and the subsurface
Authors A. Bouvier and R. LagabrielleQuality, "a set of properties and characteristics belonging to a product or a service which endow it with the aptitude to satisfy expressed or implicit requirements" , is of major importante for modern economies.
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Classification of borehole sources
By E. FromyrThe first explicit investigation of the physics of downhole sources was carried out by Heelan (1953). Since then, and in particular during the past 10 years, the onderstanding has grown and seems to have reached a mature state. This seems to be valid both as far as pure mathematical onderstanding is concerned, bot more important the validity of the idealized models for real sources. The reason for the current interest for source physics is the growth of crosswell data acquisition for tomography and crosswell reflection surveys. In all these applications the wavelengths are much longer than the borehole radius which makes it possible to obtain analytical solutions. It appears to be difficult to design good downhole sources suited for every situation and geometry. My proposition is that with proper use of currently available theory one can at least explain why this is so, and draw some practical conclusions with respect to design of such sources. This paper aims at summarizing the present state of the art in terms of theory, interpret some observation data and set up some design guidelines
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Recent advances in the development of a terfenol-D marine vibrator
Authors B. Ursin-Holm, M. Brink, R. Fritsvold and R. TenghammDuring late 1989 Saga Petroleum a.s, Norsk Hydro a.s and EB Seatech entered into an agreement for developing a new and improved Marine Vibrator source. The new development which was based on the use of the magnetostrictive material Terfenol-D was directed at first towards improved High Resolution Geophysical surveys.
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Snowstreamer design and experimental results
Authors E. Rygg, K. Rød, P. Riste, I. Sandø and P. FjellangerThe first successful lage scale experiments using towed cables with gimballed instruments in seismic data acquisition on land were performed on Spitzbergen during spring 1988. 300 km high quality seismic data were collected and the results are reported in Eiken et al. (1989) and Rygg et al. (1989). Since then a number of tests and surveys have been done in different parts of the world, e.g. West Siberia, Spitzbergen, Antarctica and Canada, and the concept has become well known under the name "Snowstreamer" because of the resemblance to marine techniques and because of the proven performance in snow-covered areas.
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Determination of the source siganture of a dynamite source using the source scaling law
Authors K. N. Bokhorst and A. M. ZiolkowskiIn land seismic data acquisition using a dynamite source it is normally impossible to measure the source signature. In most geologies the measurement is contaminated by scattered energy, and it is impossible to separate the incident field from the scattered field. However, in any serious attempt to invert the seismic data using wave propagation theory, it is essential to know the signature at the source; for the dynamite source this signature is the volume injection function.
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Structural evolution of the sea of Marmara
Authors N. Sarbay and M. TurkarslanThe purpose of this study is to shed light on the structural evolution of the Sea of Marmara, using available geologic and seismic data. Tectonic framework of the Sea of Marmara was established by tectonic events that took place between Miocene and recent. In the region, there are three area or plates (S .Marmara, N .Maramara and Thrace) which are divided by the late Tertiary transform fault boundaries. Each area has a rotational characteristic depentent on the transform faults that define a certain set of tectonic styles. E-W directed North Anatolian Transform Fault seperates south Marmara block from the North Marmara block.
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Pseudo synthetic seismogram from statistically derived sonic log: a case history
Authors L. Aleotti and M. CesaroGeological and geophysical review of mature areas with old wells having only a limited set of logs, has often to tackle the problem of a correct time-depth conversion that is necessary for a suitable identification of horizons interpreted on seismic sections. The lack of acoustic logs, in fact, cannot be compensated by using check shots survey data that, particularly in case of stratigraphic interpretation, do not offer a sufficient detail. In these situations it is necessary to develop a methodology allowing the automatic reconstruction of the sonic curve. In the shows example, the reconstruction has been done following a statistical-probabilistic approach differentiating from any deterministic method (Faust,1955) based on a predetermined mathematical formula empirically extrapolated.
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An integrated study of South Casper Creek Field, Natrona County, Wyoming, USA
Authors R. D. Benson and T. L. DavisThe South Casper Creek field is located on the Casper Arch between the Wind River Basin and the Powder River Basin, approximately 39 km west of Casper, Wyoming, U.S.A. The field was discovered in 1918 when a well was drilled on the anticlinal structure in the Jurassic Sundance Sandstone at a depth of 425m. In 1922, upon deeper drilling, oil was discovered in the deeper Pennsylvanian Tensleep Sandstone at a depth of 750m.
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Application of geostatistic regularities in seismic interpretation
More LessGeostatistic regularities represent relationship between conditions for occurence and rock properties which depends on geologic event genesis but takes into account impact only of the main reasons for such relationship to be initiated.
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Processing and interpretation of sideswipe and other external reflections from salt plugs
Authors J. Hospers and J. S. RathoreA study is presented of the genuine external specular reflections from salt plugs which manifest themselves on individual seismic sections as apparently unconnected foreswipe and backswipe reflections for seismic lines that cross salt plugs and as sideswipe reflections for lines that pass them by. It is shown that these external reflections can be combined, mapped and seismically migrated.
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3D lithostratigraphic modelling
More LessAccurate reservoir description requires integration and stratigraphic correlation of all available geophysical, petrophysical, mud logs, drilling logs, well information and production data.
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Submarine fan complex offshore Mauritania
Authors Y. Gou and A. ReymondA giant fan complex lies offshore Mauritania, in moderate waters. It extends over 160 km in the east-west direction, from the shelf-break to the west, and 80 km in the north-south direction. It has accumulated over more than 3000 metres of deposits from Aptian to Paleocene in age.
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Geophysical prospection of paleovolcanoes and teltonic faults in the Bacadjic area (South East Bulgaria)
Authors L. Nikova, D. Jossifov, D. Tzvetkova and V. NedevThe Bacadjic area was explored with many geophysical methods - gravimetric, magnetometric, aerogamaspectrometric, electrical, seismic, determination of physical properties. Such a large number of geophysical prospections is due to the fact that this region appears to present a rich are potential, but traditional geological prospections are difficult because of the great hydrothermal alteration of the rocks and the presence of pliocene deposits.
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Stratigraphic interpretation using knowledge based techniques
Authors M. T. Galli, P. Rocchini and M. VivierThe need to have accurate seismo-stratigraphic interpretations, the optictal utilization and the retention of company's experiences in this field make appropriate the use of Expert Systems as support to geophysicists' activities.
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The utility of shale compaction analysis in determining structural development Northern Interior Basin, Gabon
By R. J. BehamThis study relates the results of an analysis of shale compaction in eight wells within the Northern Interior Basin of Gabon. The analysis, using sonic log derived interval transit times, was performed to aid in the interpretation of structural development within the Ndombo permit. The permit area is characterized by major growth faults, extensive erosion and multiple periods of deformation. The complicated geology, a lack of definitive palynologic markers and generally poor quality transition zone seismic data made conventional well and seismic correlation inadequate. It was hoped that the determination of shale compaction would allow estimates of erosion and stratigraphic position of sediments encountered in the wells to be made.
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Automatic fault: pattern reconstruction and 3D structural inversion
Authors M. Papin, P. Gallupo, I. Finetti and R. GelettiThe geological models obtained from the interpretation of seismic reflection data sets are the final result of the analysis and syntheses of a remarkable amount of geophysical and geological information.
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Detection of shallow gas accumulations and uncontrolled gas flow by means of velocity and AVO analysis
More LessTwo seismic reflection profites (50 and 20 km long) were shot over several hydrocarbon reservoirs in Middle Miocene to Upper Pliocene sequences in south-eastern Hungary. Here the basement which forms an anticline is made up of four clearly distinguishable zones of NW-SE strike. The four units of the anticline consist of mesozoic rocks, metamorphic rocks, mesozoic rocks again, and granite. The anticline is surrounded by two large depressions in which great mass of source rock is known. From these rocks hydrocarbon migration occured.
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