A dynamic deterministic model of hydrocarbon generation in the Midgard Field drainage area offshore Mid-Norway     

E. S. Mo  T. Throndsen  P. Andresen  S. A. Bäckström  A. Forsberg  S. Haug  B. Tørudbakken 《International Journal of Earth Sciences》1989,78(1):305-317

The Midgard Field offshore mid-Norway is a gas-condensate accumulation with a thin oil leg reservoired in Early and Middle Jurassic sandstones. There are two potential source rocks in the area; the Late Jurassic Spekk Formation is a marine shale with type II kerogen and a rich potential for oil, and the Åre Formation of Early Jurassic age which is a thick coal-bearing sequence with type III kerogen and potential mainly for gas. Geochemical analyses indicate that both the condensate and the oil leg are sourced mainly from the coal-bearing Åre Formation. Any contribution from the Spekk Formation appears to be of minor importance. Computer simulation of hydrocarbon generation in the drainage area for the Midgard Field indicates that huge volumes are formed, and confirms that hydrocarbon generation from the Åre Formation is volumetrically far more important than from the Spekk Formation. The simulation results also exclude any contribution to the reservoired gas from the Spekk Formation.

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Zusammenfassung Das Midgard Feld vor der Küste Mittelnorwegens ist eine Gas-Kondensat-Akkumulation mit einem nur geringen Ölanteil innerhalb unter- und mitteljurassischer Sandsteine. In diesem Gebiet gibt es zwei mögliche Muttergesteine: Einmal die oberjurassische Spekk-Formation, bei der es sich um einen marinen Schiefer mit Typ II Kerogen handelt und die ein hohes Ölpotential darstellt. Zum anderen gibt es die unterjurassische Åre-Formation, eine mächtige Kohle-führende Folge mit Typ III Kerogen und ein möglicher Gaslieferant. Geochemische Analysen deuten darauf hin, daß sowohl das Gas-Kondensat als auch das Öl des Midgard Feldes auf diese Kohle-führende Åre-Formation zurückzuführen sind. Jede Zufuhr aus der Spekk-Formation scheint von geringer Bedeutung zu sein. Eine durch Computersimulation rekonstruierte Kohlenwasserstofferzeugung im Einzugsgebiet des Midgard Feldes spricht für eine hohe Bildungsrate und bestätigt die Annahme, daß die Kohlenwasserstoff-produktion der Spekk-Formation gegenüber der Åre-Formation zu vernachlässigen ist. Die Simulation ergab ferner, daß keinerlei Gas von der Spekk-Formation dem Reservoir zugeführt wurde.

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Résumé Le champ off-shore de Midgard (Norvège moyenne) est une accumulation de gaz condensé accompagnée d'un mince corps d'huile, accumulation renfermée dans des grès d'âge jurassique inférieur et moyen. Il existe dans le secteur deux sources possibles: la formation de Spekk (shale marins du Jurassique tardif, à kérogène de type II, possédant un riche potentiel en huile) et la formation d'Åre (série épaisse jurassique inférieure, à couches de charbon, à kérogène de type III et potentiel essentiellement en gaz). Les analyses géochimiques montrent que le gaz condensé et l'huile ont tous deux comme origine la formation charbonneuse de Åre. La formation de Spekk ne semble être intervenue que de manière subordonnée. Une simulation par ordinateur de la genèse de l'hydrocarbure dans l'aire d'alimentation du champ de Midgard fait apparaître que des volumes importants ont été formés et confirme la large prépondérance de la formation de Åre parmi les roches-mères. De plus, cette simulation exclut toute expèce de contribution de la formation de Spekk dans la genèse du gaz.

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Midgard / / . : Spekk — , 2, , Are , 3 . . . , Are. Spekk, , . Midgard , Are . , , Spekk .

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Should Women Count? A Context for the Debate*     

Doreen J. Mattingly  Karen Falconer-Al-Hindi 《The Professional geographer》1995,47(4):427-435

Much recent feminist geographical scholarship emphasizes the utility of qualitative research methods; yet, a significant proportion of feminist research in geography is quantitative. Geographers' engagement with the ideas of feminist theorists has shed new light on the relationship between epistemology, methodology, and objectivity, which in turn has facilitated a reexamination of feminist uses of quantification. In providing a context for the debate over quantitative and qualitative methods, we argue that each has a place in feminist geographical research.  相似文献   

Experimental studies on the phase systems Fe-Ni-Pd-S and Fe-Pt-Pd-As-S applied to PGE deposits     

Emil Makovicky  Sven Karup-Møller  Milota Makovicky  Jhon Rose-Hansen 《Mineralogy and Petrology》1990,42(1-4):307-319

Summary In the present paper current results of experimental investigation of the phase system Pd-Fe-Ni-S at 900°C, 725°C, 550°C and 400°C as well as of the phase system Pt-Fe-As-S at 850°C and 470°C are summarized. A preliminary note on the system Pt-Pd-As-S is added. Individual phase assemblages are presented, data on solubility of PGE in base metal sulphides/arsenides or alloys are given and solid solution ranges of important minerals are described as a function of temperature and phase assemblage. The extent and role of sulphide/arsenide melts in these systems are presented together with hints for, and examples of the application of the current experimental results for the explanation of ore-geological processes.

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Bisherige Ergebnisse experimenteller Untersuchungen in den Systemen Fe-Ni-Pd-S und Fe-Pt-Pd-As-S und ihre Bedeutung für Lagerstätten der Platin-Gruppen-Elemente

Zusammenfassung In der vorliegenden Arbeit werden bisherige Ergebnisse experimenteller Untersuchungen in den Phasensystemen Pd-Fe-Ni-S bei 900°C, 725°C, 550°C sowie 400°C, bzw. Pt-Fe-As-S bei 850°C und 470°C zusammengefasst. Vorläufige Anmerkungen zum System Pt-Pd-As-S werden gegeben. Die Phasenbeziehungen und die Löslichkeitsdaten von PGE's in Buntmetall-Sulfiden/Arseniden sowie deren Verbindungen werden präsentiert. Die Mischungsbereiche der wichtigsten Minerale werden als Funktion von Temperatur und Phasenvergesellschaftung diskutiert. Die Rolle von Sulfid/Arsenid Schmelzen in diesen Systemen und Beispiele für die Anwendung dieser experimentellen Ergebnisse zur Erklärung lagerstättenkundlicher Prozesse werden beschrieben.

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With 6 Figures  相似文献   

The structural state of iron in oxidized vs. reduced glasses at 1 atm: A57Fe Mössbauer study     

David Virgo  Bjørn O. Mysen 《Physics and Chemistry of Minerals》1985,12(2):65-76

A general model for the structural state of iron in a variety of silicate and aluminosilicate glass compositions in the systems Na₂O-Al₂O₃-SiO₂-Fe-O, CaO-Al₂O₃-SiO₂-Fe-O, and MgO-Al₂O₃-SiO₂-Fe-O is proposed. Quenched melts with variable Al/Si and NBO/T (average number of nonbridging oxygens per tetrahedrally coordinated cation), synthesized over a range of temperatures and values of oxygen fugacity, are analyzed with⁵⁷Fe Mössbauer spectroscopy. For oxidized glasses with Fe³⁺/∑Fe>0.50, the isomer shift for Fe³⁺ is in the range ～0.22–0.33 mm/s and ～0.36 mm/s at 298 K and 77 K, respectively. These values are indicative of tetrahedrally coordinated Fe^3?. This assignment is in agreement with the interpretation of Raman, luminescence, and X-ray,K-edge absorption spectra. The values of the quadrupole splitting are ～0.90 mm/s (298 K and 77 K) in the Na-aluminosilicate glasses and compare with the values of 1.3 mm/s and 1.5 mm/s for the analogous Ca- and Mg-aluminosilicate compositions. The variations in quadrupole splittings for Fe³⁺ are due to differences in the degree of distortion of the tetrahedrally coordinated site in each of the systems. The values of the isomer shifts for Fe²⁺ ions in glasses irrespective of Fe³⁺/∑Fe are in the range 0.90–1.06 mm/s at 298 K and 1.0–1.15 mm/s at 77 K. The corresponding range of values of the quadrupole splitting is 1.75–2.10 mm/s at 298 K and 2.00–2.35 mm/s at 77 K. The temperature dependence of the hyperfine parameters for Fe²⁺ is indicative of noninteracting ions, but the values of the isomer shift are intermediate between those values normally attributable to tetrahedrally and octahedrally coordinated Fe²⁺. The assignment of the isomer-shift values of Fe²⁺ to octahedral coordination is in agreement with the results of other spectral studies. For reduced glasses (Fe³⁺/∑Fe≈<0.50), the value of the isomer shift for Fe³⁺ at both 298 K and 77 K increases and is linearly correlated with decreasing Fe³⁺/∑Fe in the range of \(f_{O_2 } \) between 10^?3 and 10^?6 atm when a single quadrupole-split doublet is assumed to represent the absorption due to ferric iron. The increase in value of the isomer shift with decreasing \(f_{O_2 } \) is consistent with an increase in the proportion of Fe³⁺ ions that are octahedrally coordinated. The concentration of octahedral Fe³⁺ is dependent on the \(T - f_{O_2 } \) conditions, and in the range of log \(f_{O_2 } \) between 10^?2.0 and 10^?5 a significant proportion of the iron may occur as iron-rich structural units with stoichiometry similar to that of inverse spinels such as Fe₃O₄, in addition to isolated Fe²⁺ and Fe³⁺ ions.  相似文献   

Advances in physical geochemistry | S.K. Saxena (Editor), 1982. Vol. 2. I. Ferromagnesian silicates: order-disorder,kinetics, and phase equilibria; II. Melts,fluids, and solid-fluid equilibria; III. Thermodynamic methods and data. Springer-Verlag,New York, 353 pp. (113 figs.), DM94.000, approx. US$41.80 (clothbound)     

Bjørn Mysen 《Earth》1984,20(3):251-252

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Lake Søbygaard: a shallow lake in recovery after a reduction in phosphorus loading     

M. Sc. Søndergaard  E. Jeppesen  O. Sortkjaer 《GeoJournal》1987,14(3):381-384

The development and recovery of a shallow and hypertrophic lake following a reduction in the external phosphorus load has been documented. In spite of this reduction, phosphorus concentrations and phytoplankton biomass in the lake water are still very high. The reason for this development can be explained by three main factors: (1): the sediment has been accumulating a large phosphorus pool which is now causing a high internal phosphorus load, (2) due to the shallow conditions, resuspension of the upper sediment often takes place because of wind action and thereby increases the phosphorus loading from the sediment, (3) the development of a large population of planktivorous fish decreases the zooplankton biomass resulting in the development of a large phytoplankton biomass.  相似文献   

Olivine phenocrysts of Hawaiian olivine tholeiite and oceanite   总被引：4，自引：0，他引：4  

Sven Maaløe  Birger Hansen 《Contributions to Mineralogy and Petrology》1982,81(3):203-211

Olivine phenocrysts of Hawaiian tholeiites display a variety of textures and a variation in composition which is due to supercooled crystallization. The highest forsterite content measured is 91%, and the highest magnesia content estimated for a tholeiitic liquid is 17%, using the olivine geothermometer. The liquid of this composition may be either a primary magma or a primitive magma. It is not yet possible to specify any particular composition range for the primary Hawaiian tholeiites.  相似文献   

Hypersthene-ilmenite(/magnetite) symplectites in coronitic olivine-gabbronorites     

H.P. Zeck  H.H. Shenouda  J.G. Rønsbo  R.P.E. Poorter 《Lithos》1982,15(3):173-182

Symplectitic intergrowths of hypersthene (host) with ilmenite and minor magnetite (vermicules) in a gabbroic sill from the Precambrian of southwest Sweden occur as replacement products of olivine, and are thought to have formed simulataneously with the replacement of nearby crystals of ilmenite and Timagnetite by biotite and hornblende (and spinel). These interrelated replacement processes may have taken place during, or immediately after, the final stages of the magmatic crystallization, at temperatures of about 660–680°C, as part of the inherent metamorphism of the gabbroic rock. Another expression of this metamorphic imprint is the occurrence of two-tiered corona shells of hypersthene/hornblende (+spinel) at the interface of olivine and plagioclase crystals.  相似文献   

Tracer experiments with turbulently dispersed air ions     

P. B. Storebø  T. Bjorvatten  K. Hønn»shagen  A. Lillegraven  C. D. Jones  C. J. P. Van Buijtenen 《Boundary-Layer Meteorology》1983,26(2):127-139

Unipolar air ions released into the wind constitute a tracer which can be measured with high resolution. An ion source produces a cloud with homogeneous charge density, insensitive to source strength, dependent on time since formation only. It is well suited for tracing concentration changes due to turbulence, less suited for cloud size tracing. A tight array of 8 sensors has been used to examine turbulently dispersed ions. High-resolution records are presented and discussed. The highest concentrations measured could be undiluted source material. The frequency distribution within a plume did not differ from that in a multitude of puffs. The distribution seems to be log-normal with a geometric standard deviation of about 2.45. The time resolution used corresponds to volume resolutions of 40, 225, and 650 cm³. Sample size had no apparent effect.  相似文献   

Low frequency waves in plasmas with spatially varying electron temperature     

P. Guio  S. Børve  H. L. Pécseli  J. Trulsen 《Annales Geophysicae》2001,18(12):1613-1622

Low frequency electrostatic waves are studied in magnetized plasmas with an electron temperature which varies with position in a direction perpendicular to the magnetic field. For wave frequencies below the ion cyclotron frequency, the waves need not follow any definite dispersion relation. Instead a band of phase velocities is allowed, with a range of variation depending on the maximum and minimum values of the electron temperature. Simple model equations are obtained for the general case which can be solved to give the spatial variation of a harmonically time varying potential. A simple analytical model for the phenomenon is presented and the results are supported by numerical simulations carried out in a 2.5-dimensional particle-in-cell numerical simulation. We find that when the electron temperature is striated along B₀ and low frequency waves (_ci) are excited in this environment, then the intensity of these low frequency waves will be striated in a manner following the electron temperature striations. High frequency ion acoustic waves (_ci) will on the other hand have a spatially more uniform intensity distribution.  相似文献