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Chin-Fu Tsang Jan-Erik Rosberg Prabhakar Sharma Theo Berthet Christopher Juhlin Auli Niemi 《Hydrogeology Journal》2016,24(6):1333-1341
Drilling of a deep borehole does not normally allow for hydrologic testing during the drilling period. It is only done when drilling experiences a large loss (or high return) of drilling fluid due to penetration of a large-transmissivity zone. The paper proposes the possibility of conducting flowing fluid electrical conductivity (FFEC) logging during the drilling period, with negligible impact on the drilling schedule, yet providing important information on depth locations of both high- and low-transmissivity zones and their hydraulic properties. The information can be used to guide downhole fluid sampling and post-drilling detailed testing of the borehole. The method has been applied to the drilling of a 2,500-m borehole at Åre, central Sweden, firstly when the drilling reached 1,600 m, and then when the drilling reached the target depth of 2,500 m. Results unveil eight hydraulically active zones from 300 m down to borehole bottom, with depths determined to within the order of a meter. Further, the first set of data allows the estimation of hydraulic transmissivity values of the six hydraulically conductive zones found from 300 to 1,600 m, which are very low and range over one order of magnitude. 相似文献
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Observed redshifts and magnitudes of seven classes of extragalactic objects, and number counts of QSRS are compared with predictions made by cosmological models. The uniform model U 1 and the proposed non-expanding model RHL 5 represent the observations very well. The latter offers numerous advantages. Absolute magnitudes and colors are determined. 相似文献
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Jan-Erik Rosberg 《Hydrogeology Journal》2010,18(5):1291-1300
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William M. Farrell Jan-Erik Wahlund Michiko Morooka Donald A. Gurnett William S. Kurth Robert J. MacDowall 《Icarus》2012,219(1):498-501
As the saturnian magnetoplasma sweeps past Enceladus, it experiences both a decrease in electron content and sharp slowdown in the northern hemisphere region within ～5 Enceladus Radii (Re). This slowdown is observed by Cassini in regions not obviously associated with the southern directed plume-originating ions. We suggest herein that the decrease in northern hemisphere electron content and plasma slowdown could both be related to the presence of fine dust grains that are being accelerated by the Lorentz force created within the saturnian magnetic field system. 相似文献
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During flow testing of a deep, 1927-m, gravel packed screen completed well, it became apparent that well development was needed to increase productivity. A hydrojetting system using coiled tubing in combination with simultaneous pumping was developed and tested and found to be successful. To verify whether the jetting improved the well, the results of a pumping test conducted before and after the jetting operation are compared. In addition, flowmeter logging and hydraulic properties obtained from pumping tests conducted during the jetting operation were also used to verify the improvements. Hydrojetting in combination with simultaneous pumping proved to be an effective cleaning method. After 100 min of pumping, around 110 m less drawdown and 15 L/s higher average flow rate were obtained compared to the values before the jetting operation. The skin factor was positive before the jetting operation and negative thereafter, thus providing additional evidence of improvements of the well. The flowmeter data also confirmed the improvements and were valuable in optimizing the jetting operation. It was also found, from the short-term pumping tests conducted during the jetting operation, that the Hantush–Jacob method for leaky confined aquifers is a valuable indicator of the well development. The combination of methods used for the well development in this case can easily be applied on other deep well projects to obtain a controlled and time-efficient well development. 相似文献
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Christine Doughty Chin-Fu Tsang Jan-Erik Rosberg Christopher Juhlin Patrick F. Dobson Jens T. Birkholzer 《Hydrogeology Journal》2017,25(2):501-517
Flowing fluid electrical conductivity (FFEC) logging is a hydrogeologic testing method that is usually conducted in an existing borehole. However, for the 2,500-m deep COSC-1 borehole, drilled at Åre, central Sweden, it was done within the drilling period during a scheduled 1-day break, thus having a negligible impact on the drilling schedule, yet providing important information on depths of hydraulically conductive zones and their transmissivities and salinities. This paper presents a reanalysis of this set of data together with a new FFEC logging data set obtained soon after drilling was completed, also over a period of 1 day, but with a different pumping rate and water-level drawdown. Their joint analysis not only results in better estimates of transmissivity and salinity in the conducting fractures intercepted by the borehole, but also yields the hydraulic head values of these fractures, an important piece of information for the understanding of hydraulic structure of the subsurface. Two additional FFEC logging tests were done about 1 year later, and are used to confirm and refine this analysis. Results show that from 250 to 2,000 m depths, there are seven distinct hydraulically conductive zones with different hydraulic heads and low transmissivity values. For the final test, conducted with a much smaller water-level drawdown, inflow ceased from some of the conductive zones, confirming that their hydraulic heads are below the hydraulic head measured in the wellbore under non-pumped conditions. The challenges accompanying 1-day FFEC logging are summarized, along with lessons learned in addressing them. 相似文献
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Richard C. Ghail Colin Wilson Marina Galand David Hall Chris Cochrane Philippa Mason Joern Helbert Franck MontMessin Sanjay Limaye Manish Patel Neil Bowles Daphne Stam Jan-Erik Wahlund Fabio Rocca David Waltham Tamsin A. Mather Juliet Biggs Matthew Genge Philippe Paillou Karl Mitchell Lionel Wilson Upendra N. Singh 《Experimental Astronomy》2012,33(2-3):337-363
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Jan-Erik Lindqvist 《International Journal of Earth Sciences》1987,76(3):837-850
The rocks of the Nasafjäll Window comprise Proterozoic granitoids with a metasedimentary cover of Late Precambrian to Ordovician age, the Mierkenis Group. The metamorphic grade in the window varies from greenschist facies in the eastern part of the window to amphibolite facies in the western part. The metamorphic maximum is syn- to post-kinematic in relation to the formation of the thrust-related pervasive foliation. This suggests a rapid basement heating in response to the Late Silurian to Early Devonian nappe emplacement. The Caledonian metamorphism terminated in Middle Devonian times and the retrograde phase was characterized by decompression. This implies that the later stage of the thrusting was not associated with an increase in thickness of the nappe pile above the rocks of the Nasafjäll Window.
Zusammenfassung Die Gesteine im Nasafjällfenster in den nördlichen Skandinavischen Kaledoniden bestehen aus proterozoischen Granitoiden mit einer spätpräkambrischen bis ordovicischen Decke, der Mierkenis Gruppe. Im Fenster erhöht sich der Metamorphosengrad von der Grünschieferfazies im Osten zur Amphibolitfazies im Westen. Bezüglich der penetrativen Verschieferung, die während der Überschiebungen entstanden ist, ist das metamorphe Maximum synbis post-kinematisch. Zur Erklärung dieser Beobachtungen ist vorgeschlagen, daß zur Folge der spätsilurischen bis frühdevonischen Überschiebungen sich die Temperatur des Grundgebirges schnell erhöhte. Die kaledonische metamorphe Phase war von Druckentlastung geprägt. Diese Interpretationen schlagen auch vor, daß die späteren Stadien der Überschiebungen nicht mit einer Zunahme der Mächtigkeit von der Überschiebungsdecke verbunden waren.
Résumé Les roches de la fenêtre de Nasafjäll (Calédonides scandinaves) comprennent des granitoïdes protérozoïques et une couverture métasédimentaire d'âge précambrien supérieur à ordovicien. Ces métasédiments font partie du groupe Mierkenis. Le degré métamorphique varie du faciès des schistes verts dans l'est de la fenêtre au faciès des amphibolites dans l'ouest. Le métamorphisme maximal est syn- à post-cinématique; il est lié à la genèse de la schistosité pénétrative, en relation avec le charriage. Cette observation suggère un échauffement rapide du socle consécutif à la mise en place de la nappe au Silurien supérieur et au Dévonien inférieur. Le métamorphisme calédonien a pris fin au Dévonien moyen et sa phase rétrograde a été caractérisée par une baisse de la pression. En conséquence, la dernière phase du charriage n'a pas été associée à une augmentation de l'épaisseur de la nappe sur les roches de la fenêtre de Nasafjäll.
Nasfjäll — Mierkenis. . , , . , . . , .相似文献
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Cyprinid fish have pharyngeal teeth that mash ingested food. Here we show that roach (Rutilus rutilus L.), a common cyprinid in Swedish boreal lakes, often break the mandibles of ingested Chaoborus larvae into smaller fragments. The presence/absence of roach in historic fish communities could therefore possibly be determined
from the proportion of fragmented Chaoborus mandibles in lake sediments, which we assessed using the following three approaches. (1) Roach that were fed Chaoborus larvae in laboratory aquaria evacuated a significantly higher fraction of fragmented prey mandibles than perch (Perca fluviatilis L.). (2) Surface sediments from lakes in an acidified region in southwestern Sweden showed significantly higher proportions
of fragmented mandibles for lakes containing roach compared to lakes devoid of cyprinid fish. (3) A paleo-study in Lake Lysevatten,
into which roach were introduced in the 1880s and were extirpated in the 1960s, showed significantly higher proportions of
fragmented mandibles in sediment layers from the roach period. We conclude that mandible fragmentation was related to roach
presence, and propose that the proportion of fragmented Chaoborus mandibles in lake sediments may provide important information when historical cyprinid alterations are of interest, as in
paleo-studies on acidification, eutrophication, or fish introductions. 相似文献
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