- Home
- Conferences
- Conference Proceedings
- Conferences
61st EAGE Conference and Exhibition
- Conference date: 07 Jun 1999 - 11 Jun 1999
- Location: Helsinki, Finland
- ISBN: 978-90-73781-10-8
- Published: 07 June 1999
1 - 50 of 502 results
-
-
Seismic Velocity Structure at the Gas Hydrate Reflector - Indonesia and Pakistan
Authors C. Gavrila, J. Sheiman and J. RyanThis paper describes the experimental processing of foor seismic lines, in which we attempted to learn more about the transition to and from a phase in which gas is trapped in the foren of a methane hydrate . The gas hydrate phase occurs in a temperature/pressure regime that is typically found a few hundred metres below a deep water seafloor . The transition is expressed as a so-called Bottom Simulating Reflector (BSR) ; so named because its structure mimics that of the seafloor rather than follówing the local bedding direction. Indeed reflections associated with bedding planes often cross through the BSR . In addition to the BSR, we looked for changes in seismic interval velocity, amplitude and AVO effects in the neighbourhood of the BSR. All of these help us to glean information about the nature of the gas hydrate, its generation and the hydrate / free-gas transition .
-
-
-
The Effect of Acquisition Direction on Pre-Sdm Imaging
Authors I. F. Jones, H. Baud, B. Henry, A. Strachan, J. Kommedal and M. GainskiA production 3D preSDM p roject .from the southern North Sea using several vintages of input data was run using a velocity-depth model common to the whole area , with goud fnal results . The expected progress ive improvement from postSTM to postSDM to preSDM was demonstrated for the target horizons.
-
-
-
Depth Imaging in the Heide-Buesum Transition Zone Area
Authors J. Navarro, J. Thiessen, H. -J. Zoch, H. Janie and K. FischerThe recent Heide -Busum TZ 3D survey from RWE-DEA AG and Wintershall AG presented unusual challenges for depth imaging . Seismic data had to be acquired offshore; in the transition zone and on land . The three datasets were combined with proper source designature and phase matching. The acquisition also made use of the patch technique, resulting in ve ry irregular fold and offset distribution . A new type of normalization, by fold density as a function of offset, is presented that corrects some of these problems .
-
-
-
Mapping Sub-Basalt Reflectors Using Model-Based Analysis
Authors L. Sønneland, J. O. Hansen, B. Tjøstheim, B. Larssen and S. JåsundThe continental break-up of the Northern European plate and the Greenland plate during the Paleocene age was associated with transient, massive volcanism. This resulted in that volcanic rocks such as basalts covered a significant part of land-surface and sea-beds of Paleocene age. It is well known that the main hydrocarbon reservoirs in Europe are in sedimentary layers of older age than Paleocene. As a consequence many sedimentary sequences of highest hydrocarbon potential are overlaid by lava-deltas.
-
-
-
Seismic Imaging Surveys at the Apso Hrl
More LessBorehole seismic imaging surveys have been undertaken over a range ofdifferent scales at the Aspo Hard Rock Laboratory (HRL) to address a number of different objectives. In this paper two of those objectives, that encompass the end members of the range of scales are presented and discussed.
-
-
-
Algorithmic Approaches to Psdm for Imaging Beneath Salt Structures - An Example from the Uk Sns
Authors C. Docherty, M. Sugrue and A. StrongAreas of structural complexity that include strong lateral velocity contrasts prove considerable obstacles for imaging and are best addressed by pre-stack depth migration (PSDM) . However, the ability of PSDM schemes to tackle such problems is varied and much depends on the approach to initial velocity model building. An excellent testing area for PSDM is provided by a steep (and/or fault) sided salt diapir piercing its overburden. We outline the fundamental differences between two PSDM schemes from separate contractors and present their success on imaging a 2D data set over a prospect underlying salt in Southern North Sea Block 48/3b.
-
-
-
Sub-Basalt Imaging Improvements - West Hebrides
More LessStandard seismic processing and controlled stacking of mode converted energy has proven successful in sub-basalt imaging (most recently Emsley et al., 1998; Longshaw et al., 1998). There is however, widespread scepticism about the nature of the imaged reflectors (sub-basalt primary vs. multiple). In this paper, we present new results from migration of long-offset data (12.5 km) that were acquired in 1996 by Phillips Petroleum over Tertiary flood basalt in the Rockall Trough, NW of the Hebrides.
-
-
-
Enhanced Composite 3D Cube Derived from Multi-Azimuth 3D Marine Acquisitions
Authors H. Houllevigue, H. Delesalle and E. De BazelaireIn Seismic imaging, the influence of the angle between the acquisition azimuth and the main axis of geological structures has been well known for a long time (Levin 1971). Many analytical studies have been undertaken but rather few on real cases (Bullwinkle 1993). This azimuthal sensitivity is enhanced in complex tectonic, leading to complex rays trajectories.
-
-
-
Two-Dimensional Textures and Prediction-Error Filters
Authors J. Claerbout and M. BrownFor many years it has been true that our most powerful signal-analysis techniques are in one-dimensional space, while our most important applications are in multi-dimensional space. The helical coordinate system introduced by Claerbout (Geophysics, 1998, vol 63, no 5) makes a giant step towards overcoming this difficulty. Figure 1 shows how convolution in two dimensions is equivalent to that in one dimension.
-
-
-
MSVE - a Novel Approach to Statistical Estimation of Primaries Superimposed on Incoherent Multiples
Authors G. A. Ryzhikov and M. S. BiryulinaThe problem of attenuation of multiples is of permanent interest for theoreticians as well as for practical geophysicists (e.g. [1]). Classical approaches to suppression of multiples exploit a well-seen self-repetition of wave-forms, resulting in a rather high correlation of primaries and respective multiples (coherent-, or waveform preserved-, reverberations).
-
-
-
Prediction and Subtraction of Multiples from Complex Water-Bottom
More LessThe main differences between our scheme for prediction and subtraction of multiples from complex water-bottom and other wave-equation approaches (see references) are the following : 1) By applying the adaptive subtraction of the predicted multiples in the tau-p domain, we take into account the angle-dependency of the reflection coefficients from the water-bottom ; 2) We do not split the subtraction procedure into two steps - first subtraction of the 'pure' multiples and receiver-side peg-legs, then subtraction of source-side peg-legs.
-
-
-
A Comparison of the Feedback and Inverse Scattering Internal Multiple Attenuation Methods
Authors D. J. Verschuur, K. H. Matson, A. J. Berkhout, A. B. Weglein, C. Y. Young and H. JakubowiczMethods for removal of free-surface and internal multiples have been developed From both a feedback model approach and inverse scattering theory.
-
-
-
Integration of OBS Data and Surface Data for OBS Multiple Removal
Authors D. J. Verschuur and E. I. NeumannThe surface-related multiple elimination method, based on the work of Berkhout (1982) and described as a data adaptive procedure by Verschuur et al. (1992), has already been applied successfully to several marine and land datasets, as shown by e.g. Verschuur and Werkhout (1997), Verschuur et al. (1995) and Kelamis and Verschuur (1996).
-
-
-
Multiple Attenuation of Multicomponent Ocean-Bottom Data According to an Elastic Model
By R. SoubarasIn multicomponent ocean-bottom acquisitions, hydrophone data is acquired together with vertical and horizontal geophone data. The pressure and vertical velocity measurements are contaminated by ghosts and peg-leg multiples and must be merged for water-lager multiple attenuation. In this paper, a method is presented for water-lager multiple attenuation which takes into account nonvertical propagation and the elastic nature of the water-bottom without requiring the subsurface elastic parameters to be known, nor the measurements to be well calibrated.
-
-
-
Elastic Waves in Three-Phase Poroelastic Media
Authors A. Bakulin and L. MolotkovReal rocks are often multiphase. Two-phase porous rocks consisting of skeleton and fluid are well described by Biot model.
-
-
-
The Effects of Porosity - Pore-Fluid and Mineralogy on VpNs in Carbonate Rocks
Authors S. Assefa, C. McCann, J. Sothcott, T. Astin and S. JohnstadCarbonates are important hydrocarbon reservoir rocks. They have complex textures and petrophysical (porosity and permeability) properties.
-
-
-
Wave Refraction with a Porous Plate in Liquid - Comparison of Biot's and Bisq Theories
More LessA comparison of the theoretical results for wave refraction by a porous plate immersed in a liquid with the experimental ones is made both for Biot's and BISQ models of porous medium. BISQ model is found to be more adequate to the experiment from the viewpoint of fast pressure wave attenuation, but less adequate from the viewpoint of slow pressure wave generation than Biot's model.
-
-
-
Acoustic Velocities in Partially Saturated Sandstones Versus Effective Stress
Authors A. Khaksar and C. GriffithsThe influence of saturation by water, gas, and mixtures thereof on velocities and elastic moduli of reservoir rocks is of considerable interest in exploration seismology.
-
-
-
Modelling Rock Behaviour with Linear Slip Deformation Theory
More LessThe dynamic elastic properties of rock are defined in terms of linear slip deformation theory, which is based on infinitesimal motion across weak planes being linearly related to the traction on those planes. The linear parameters governing slip on these planes though are highly non-linear functions of static stress state, and as such the theory provides a way to predict, based on a very limited set of measurements, the acoustic behavior of dry granular rock as a function of static stress.
-
-
-
Detecting Fractures in the Unsaturated Zone from Acoustic Properties
Authors R. Horobin, C. McCann and M. PriceThe presence of fractures in a rock usually have the effect of reducing the acoustic velocity and increasing the attenuation (Peacock et. al., 1994; Groenenboom and Foktrema, 1998).
-
-
-
Shear-Wave Splitting Before Earthquakes Implies Compliant Rocks Close to Criticality
By S. CrampinChanges in shear-wave splitting before earthquakes are now observed routinely at large distances whenever appropriate source-receiver-earthquake geometries exist.
-
-
-
Ape-Modelling of Fluid/Rock Deforrnation of Sandstone Cores in Laboratory Stress-Cells
Authors S. Crampin, S. V. Zatsepin, H. J. Rowlands, B. J. Smart and J. M. L. SomervilleAnisotropic poro-elasticity (APE) is a model for the evolution of fluid-saturated microcracked rock undergoing (pre-fracturing) deformation.
-
-
-
Accurate EM Modelling for Appropriate Levels of Geological and System Complexity
More LessIn order to be useful, electromagnetic modelling programs should account for all relevant complexity both in the geology and in the simulated system.
-
-
-
The Localised Non Linear Approximation - a Good Recipe for Low Contrast Ellipsoidal Bodies
Authors G. Perrusson, A. Charalambopoulos, B. Bourgeois, D. Lesselier, M. Lambert and G. DassiosVersatile 3-component frequency EM systems operating at diffusion frequencies recently became available for use in slim mineral-exploration boreholes.
-
-
-
The Application of Invariant in VLF-EM Mapping
Authors M. Djeddi, H. A. Baker and A. TabbaghWhenever an elongated 2D or 3D structure in geological, archaeological or environmental surveys found parallel to the polarising magnetic field of the VLF-EM method, this method becomes ineffective, due to the nature of the secondary field.
-
-
-
The Borehole Slipgram Method in Mineral Exploration Using the Slimboris System
Authors B. Bourgeois and C. AlayracWe introduce the single-borehole frequency-domain EM profiling method, in which a magnetic dipole transmitter (Tx), oriented along the borehole path, and a 3-component dipolar magnetic receiver (Rx) are moved together in the same borehole at a fixed separation.
-
-
-
Surface-to-Hole FEM Measurements Compared with Time Domain EM Data-in Central Finland
Authors R. Pietilä and B. BourgeoisWith the purpose of testing a frequency-domain 3-component downhole EM prototypes designed for multiple configurations (Bourgeois and Alayrac, 1999, surface-to-hole FEM data were recorded in a borehole where similar data in time-domein were already available.
-
-
-
Resistivity Inversion in the Presence of Water Saturated Fractures
By U. ZimmerFor the interpretation of resistivity inversions in fractured granite, it is necessary to estimate the effect of the fractures on the inversion result.
-
-
-
Using DC Resistivity Tomography to Detect and Characterise Mountain Permafrost
Authors C. Hauck and D. V. MühllIn the European Alps, there has recently been an increasing interest in mapping and monitoring permafrost. This is largely because of possible risks to civilization arising from increased frequency of slope instability, due to global warming.
-
-
-
2D Electrical Conductivity Structure by Magnetotelluric Method Over Eastern Indian Craton
Authors B. B. Bhattacharya and R. K. SinharayRemote reference (RR) magnetotelluric (MT) measurements were carried out over Eastern Indian craton. All the data were processed with hybrid robust technique. A stitched section was prepared from 1-D MT inversion scheme using very fast simulated annealing (VFSA) technique which served as an input data for 2-D modelling. VFSA with splines bas been used for the 2-D inversion. 2-D subsurface conductivity model over the craton shows that the granitic crust is electrically homogenous with as high a resistivity as 30,000 ohm-m. Its depth extent is 38 km.
-
-
-
Tertiary Igneous Intrusives - Establishing Their Presence to Reduce Exploration Risk
Authors P. Mulholland, S. Testa and M. WoodfinTwo separate classes of anomalous geological body have been identified on 3D seismic data acquired in a continental slope setting on the eastem margin of the Rockall Trough.
-
-
-
Special Feature of Geological and Petroleum Potential of the Kola-Kanin Monocline
More LessGeophysical data including CDP seismic (Marine Arctic Geological Expedition-MAGE, Sevmorneftegeofizika-SMNG, Murmansk, Sevoteam-joint venture Norwegian/Russian company), Wide Angle Deep Seismic Profiling-WADSP (Sevmorgeo,St .Petersburg, MAGE), refraction shooting (Institute of Physics Land, Moscow, Sevmorgeo) and gravity/magnetic (MAGE) have been intérpreted to study a Jeep geological structure of the Kola-Karin Monocline, located in the southwestem part of the Barerts Sea Shelf.
-
-
-
Geological Mapping of Arctic Shelf of Russia as a Base for Oil and Gas Occurrence Forecast
Authors R. R. Murzin, V. N. Belyaev, S. I. Shkarubo, B. G. Lopatin and E. V. ShipilovMapping of continental shelves and creation of set of maps scaled at 1 : 1 000 000 is an important part of the Russian State Programme on Geological Mapping .
-
-
-
Prospects of Oil Accumulation Discovery on Shelf of the Barents, Kara and Laptev Seas
More Less21st century envisages the increase in prospecting new oil and gas fields on the arctic shelf of Russia with special attention being paid to purposeful location of oil fields in internal (coastal) shelf not only of the Pechora sea but also of the southern parts of the Kara and Laptev seas.
-
-
-
Yurubchen-Takhom Field, the Eastern Siberian Platform - Giant Oil and Gas Accumulation in Riphean Deposits
Authors K. Sobornov, A. Afanasenkov, V. Shaidakov, V. Nesterov and Y. SokolovYurubchen-Takhom field is a giant oil and gas accumulation situated in remote area of the Krasnoyask district in Eastern Siberia.
-
-
-
Sea of Okhostk Regional 2D Survey 1998 - Stimulating Russian Offshore Exploration
Authors V. Kudelkin, P. Baillie and P. GilleranThe Sea of Okhotsk-Sakhalin Island area of Far East Russia is one of the world's most exciting petroleum exploration areas and offers unique opportunities for further major discoveries.
-
-
-
Engineering Geophysical Studies on Permafrost in the Pechora Sea
Authors O. Okko, V. Bondarev, S. Rokos and V. LisunovJoint Russian-Finnish research expeditions have been carried out to eastern Pechora Sea, in order to investigate the environmental conditions in north-eastern Europe . The engineering geophysical studies are focused on the setting of Pleistocene-Holocene sediments and on locating areas with hazardous shallow permafrost and accumulation of free gas.
-
-
-
Modelling and Comparative Analysis of Petroleum Systems
Authors G. Cadel, E. Aliverti, J. W. Roelofsen and D. J. MortimerExplorationists have ever since been used to compare sedimentary basins and provinces. To this purpose they are used to build, upgrade and invoke "models" to export information and concepts from well-known basins into less defined areas. Working by analogy is a time-consuming process which needs experience, expertise, sensibility and is based on the "processing" of a large amount of "data" (and opinions) in various formats and from different sources.
-
-
-
Overpressure - a Static or Dynamic Phenomenon?
By H. BorgeTwo conceptual models for abnormal pressures are considered (Neuzil, 1995); a static model which claims that overpressures are relicts preserved by the absence of fluid flow through geological time and a dynamic model suggesting that overpressure is a phenomenon where fluid flow plays an important role.
-
-
-
Sediments Behaviour at Basin and Geological Time Scales
By F. SchneiderBasin modelling aims to reconstruct the accumulation of hydrocarbons at basin scale, and at geological time scale, taking into account the effects of kinematics displacements, sedimentation, erosion, compaction, temperatures history, overpressures and fluids flows (water and hydrocarbons). Furthermoze, explorationists wish to address overpressure reconstruction in order to estimate the risks of drilling.
-
-
-
3D Modelling of Meander Loop Deposits
By G. MassonnatThis paper presents a method for modelling in 3D the structure and characteristics of meander-loop deposits, using a variety of techniques.
-
-
-
3D Visualisation of Architectural Patterns in Salt-Rift Basins
More LessA three-dimensional computer visualisation method has been developed for analysing and modelling of evolution of salt features and their relationship with basin tectonics. The procedure includes interpretation and correlation of seismic horizons, construction of seismic mails, depth conversion, 3D visualisation of individual surfaces and sets of layers, animation of salt diapiric motion through basin evolution.
-
-
-
Geodynamic, Geothermal and Hydrodynamic Evolution of the Broad Fourteens Basin, the Offshore Netherlands - a 2D Basin Modelling Study
Authors J. M. Verweij and H. J. SimmelinkThe study of the Broad Fourteens Basin is part of an ambitious project initiated in 1998 by the Netherlands Institute of Applied Geoscience TNO - National Geological Survey.
-
-
-
South Atlantic Margins Basin Analysis (Samba) - Gravity Constraints on Plate Reconstruction
Authors J. D. Fairhead and W. G. DicksonIntegration of satellite, land and marine gravity data from the entire South Atlantic region and improved continental margin bathymetry have been used to study and compare tectonic features on both African and South American continental margins.
-
-
-
Modelling of the Northern Caucasus Basin
Authors A. V. Ershov, M. -F. Brunet, A. M. Nikishin and S. N. BolotovThere is presented the burial history restoration of the Northem Caucasus basin. Three main stages is discriminated in the basin evolution: Middle Jurassic-Eocene stage, controlled by the rifting and postrift thermal relaxtion; Oligocene-Early Miocene stage of long wavelength pre-foreland subsidence, probably induced by the subduction-induced mantle flow; Middle Miocene-Quaternary foreland stage.
-
-
-
Magnetotelluric Sounding at Sea Bottom - Methodology and Instrumentation
Authors V. Korepanov and F. DudkinMagnetotelluric (MT) sounding is one of the best developed methods of the Earth's trust deep sounding. It is used both for scientific and applied investigations. Especially it proved to be useful for polygons choice for oil prospecting. Because many of oil deposits are in the sea bottom, marine versions of MT sounding are also developed.
-
-
-
Marine Magnetotellurics for Base Salt Mapping - a Gulf of Mexico Field Test
Authors G. M. Hoversten, S. Constable and H. F. MorrisonThe first successful marine Magnetotelluric survey in the Gulf of Mexico (GOM) has been conducted over the Gemini prospect.
-
-
-
Magnetotelluric Techniques for Offshore Exploration
Authors S. Constable and A. OrangeThe magnetotelluric (MT) method is an established technique which uses measurements of naturally occurring electromagnetic fields to determine the electrical resistivity of subsurface rocks.
-
-
-
Marine MT as a Sub-Salt Reconnaissance Tool in the Deep-Water Gulf of Mexico
More LessIn 3Q98 BP Exploration and AOA Geophysics carried out a marine MT survey in the deep-water GoM over sub-salt acreage where base salt was not imageable on seismic data.
-
-
-
Marine Magnetotelluric Data Acquisition and Processing
Authors R. Reddig, A. Orange and G. CartabiaMarine MT is evolving from a research and development project into a tool for commercial petroleum exploration.
-