Quantitative assessment of gas washing of oils in the Tazhong area of the Tarim Basin,Northwest China

Gas washing has been known in the Tazhong area of the Tarim Basin, but its quantitative assessment has not yet been reported. Here the influence of gas washing fractionation in the area was discussed based on the gas chromatogram data of 68 oils and the results of the mixing experiments of a black oil and a condensate. The results show that the intensity of gas washing fractionation decreased generally from northern to southern part and vertically from deep reservoirs to shallow reservoirs. The gas washing fractionation was mainly controlled by fault systems in this area, with the increase of n-alkane mass depletion positively correlated to the number and scale of faults. Gas washing fractionation appears to have affected the hydrocarbon property, and as a result the diversity of the crude oils is markedly controlled by gas washing. In addition, the occurrence of waxy oil in this area may be resulted from multiple factors including gas washing, mixed filling and migration fractionation. Supported by National Basic Research Program of China (Grant No. 2006CB202303) and the National Natural Science Foundation of China (Grant No. 40672091)     

Über die Änderung des Tagesganges der Luftfeuchtigkeit mit der Höhe im Gebirge

Zusammenfassung Auf Grund von Registrierungen an eng benachbarten Stationen, die im obersten Salzachtal im Land Salzburg in verschiedenen Höhenlagen zwischen Tal (900 m) und Kammhöhe (2000 m) des begleitenden Gebirgszuges gelegen waren, werden Tagesgänge der relativen Feuchtigkeit, des Dampfdrucks und der spezifischen Feuchtigkeit für Schönwettertage abgeleitet (Tab. 2). Im Vergleich dieser Stationen zeigt sich der Übergang der Form der Tagesgänge der relativen Feuchtigkeit (Abb. 2 und 3) und des Dampfdrucks (Abb. 4) von dem Typ der Niederung zu dem der Bergstationen. Der Einfluß der Konvektion und der über die feuchten Hänge streichenden Hangaufwinde auf diese Umgestaltung der Tagesgänge wird für die einzelnen Jahreszeiten quantitativ nachgewiesen und diskutiert.

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Summary Using records taken at closely neighbouring stations situated in the uppermost valley of the Salzach in the province of Salzburg at different levels between the valley-bottom (900 m) and the height of the adjacent mountain-ridge (2000 m) the diurnal variation of relative humidity, vapor pressure and specific humidity are derived for fair weather days (Tab. 2). The comparison of these stations shows the transition of the diurnal variation of relative humidity (Fig. 2 and 3) and vapor pressure (Fig. 4) from the ground type to that of the mountain stations. The influence of the convection and of the ascending currents passing over the moist slopes upon this modification of the diurnal variation is quantitatively proved and discussed for the different seasons.

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Résumé Sur la base d'enregistrements à des stations étroitement voisines situées dans la vallée la plus haute de la Salzach en province de Salzbourg à des niveaux differents entre la vallée (900 m) et l'altitude de la crête de la chaine adjacente de montagnes (2000 m) les variations diurnes de l'humidité relative, de la pression de vapeur et de l'humidité spécifique sont derivées pour les jours de beau temps (Tab. 2). En comparaison de cettes stations la transition de la forme des variations diurnes de l'humidité relative (Fig. 2 et 3) et de la pression de vapeur (Fig. 4) se présente du type de vallée à celui des stations de montagne. L'influence de la convection et des courants ascendants passant sur les pentes humides sur la transformation des variations diurnes est démontrée quantitativement et discutée.

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Mit 4 Textabbildungen.     

Handlotungen und Echolotungen in der Seevermessung geringer Wassertiefen in strömenden Gewässern — eine kritische Betrachtung

Zusammenfassung Vergleichslotungen zwischen Echolot und Handlot führen zu einer mathematischen Ableitung der Handlotleinen-Kurve in strömenden Gewässern. Durch Einführung von zwei Vereinfachungen — Vernachlässigung des Lotleinen-Gewichts und Annahme der Konstanz der Strömungsgeschwindigkeit nach der Tiefe — wird theoretisch die Kettenlinie, praktisch eine Parabel ermittelt. Als bestimmend für den Parameter der Kettenlinie ergeben sich das Lotgewicht und der Staudruck auf die Lotleine. Aus einem praktischen Beispiel wird der Parameter entnommen, und es werden für diese Verhältnisse die für die Tiefenwerte bis 26 m zu erwartenden Fehlmessungen des Handlotes sowie die Größe der Ablagen der Lotbirne vom Lotpunkt berechnet. Für andere Werte der Strömungsgeschwindigkeit werden die Veränderungen auf die Ausbuchtung der Lotleine ebenfalls rechnerisch bestimmt und in Kurven dargestellt. Aus diesen Kurven ergeben sich zwangsläufig die größten Tiefen, die man bei verschiedenen Strömungsgeschwindigkeiten mit dem schweren Handlot vermessen darf; sie liegen bei v=1 m/sec bei 8 m, bei v=0,7 m/sec bei 12 m und bei v=0,5 m/sec bei 20 m Wassertiefe.Praktische Beispiele der Seevermessung aus der jüngsten Zeit zeigen deutlich die Notwendigkeit, zukünftig nur noch mit dem Echolot zu vermessen.

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A comment on the applicability of hand leads and echo sounders to surveying operations in flowing shallow waters

Summary From comparisons between hand-lead soundings and echo soundings in streaming waters the divergency of the lead line from the vertical is mathematically derived. In introducing two simplifications, i. e. in neglecting the weight of the lead line and in assuming the velocity of current to be constant at all depths, the catenary curve which practically speaking is a parabola, is theoretically ascertained. The weight of the lead and the dynamic pressuro of the water (the pressure as exerted on a jet and measured by it) are found to be decisive for the parameter of the catenary-curve. The parameter is derived from a practical example and, according to the conditions of same, the errors to be expected in sounding with the hand lead at depths up to 26 m (= 79 ft) as well as the divergency of the sounding lead from the vertical are calculated. The various degrees of the lead line's divergency caused by a greater or lesser intensity of the current are likewise calculated and represented by curves. These curves necessarily indicate the maximum depths that can be sounded with sufficient accuracy with the heavy hand lead (5 kilos) at different velocities of current; the approximate values are as follows: 8 m for 1,0 m/sec, 12 m for 0,7 m/sec, 20 m for 0,5 m/sec (or: 25 ft for 2,0 knots, 37 ft for 1,5 knots, 61 ft for 1,0 knot). As a result of practical experience in recent survey operations the echo sounder should be regarded as the only reliable instrument to be used in future surveying.

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Note critique sur l'applicabilité de la sonde au plomb-poisson et celle du sondeur acoustique aux levés hydrographiques effectués en faibles profondeurs dans les eaux courantes

Résumé Les comparaisons des sondages au plomb-poisson avec ceux effectués par écho permettent d'en dériver mathématiquement la courbe formée par la ligne de sonde dans des eaux courantes. En introduisant deux simplifications, c'est à dire en négligeant le poids de la ligne et en supposant que la vitesse de courant soit constante dans toutes les profondeurs on arrive à déterminer théoriquement la chaînette qui est en effet une parabole. Le paramètre est fonction du poids du plomb-poisson et celle de la poussée sensiblement horizontale sur le fil due au frottement du liquide. On se sert d'un exemple pratique pour en dériver le paramètre, pour calculer, dans les conditions de cet exemple, les sondages faux de la sonde au plomb-poisson dont il faut tenir compte dans les profondeurs jusqu'à 26 m, et pour déterminer la déviation entre le plomb au bout de la ligne et la verticale. Les diverses variations de la courbe, que la ligne subit et qui sont causées par d'autres valeurs de la vitesse de courant sont aussi calculées et représentées à l'aide des courbes. Ces courbes indiquent forcément les profondeurs permettant encore une précision suffisante du sondage au plombpoisson lourd (5 kg) aux différentes variations de la vitesse de courant. Ces maxima sont à peu près comme suit:v=1,0 m/sec à 8 m de profondeur,v=0,7 m/sec à 12 m de profondeur,v=0,5 m/sec à 20 m de profondeur. Des exemples pratiques offerts par des récentes levés hydrographiques prouvent que le sondeur acoustique doit être considéré comme le seul instrument assurant le précis levé hydrographique.

     

Radium uptake during barite recrystallization at 23 ± 2 °C as a function of solution composition: An experimental Ba and Ra tracer study

High-purity synthetic barite powder was added to pure water or aqueous solutions of soluble salts (BaCl₂, Na₂SO₄, NaCl and NaHCO₃) at 23 ± 2 °C and atmospheric pressure. After a short pre-equilibration time (4 h) the suspensions were spiked either with ¹³³Ba or ²²⁶Ra and reacted under constant agitation during 120-406 days. The pH values ranged from 4 to 8 and solid to liquid (S/L) ratios varied from 0.01 to 5 g/l. The uptake of the radiotracers by barite was monitored through repeated sampling of the aqueous solutions and radiometric analysis. For both ¹³³Ba and ²²⁶Ra, our data consistently showed a continuous, slow decrease of radioactivity in the aqueous phase.Mass balance calculations indicated that the removal of ¹³³Ba activity from aqueous solution cannot be explained by surface adsorption only, as it largely exceeded the 100% monolayer coverage limit. This result was a strong argument in favor of recrystallization (driven by a dissolution-precipitation mechanism) as the main uptake mechanism. Because complete isotopic equilibration between aqueous solution and barite was approached or even reached in some experiments, we concluded that during the reaction all or substantial fractions of the initial solid had been replaced by newly formed barite.The ¹³³Ba data could be successfully fitted assuming constant recrystallization rates and homogeneous distribution of the tracer into the newly formed barite. An alternative model based on partial equilibrium of ¹³³Ba with the mineral surface (without internal isotopic equilibration of the solid) could not reproduce the measured activity data, unless multistage recrystallization kinetics was assumed. Calculated recrystallization rates in the salt solutions ranged from 2.8 × 10⁻¹¹ to 1.9 × 10⁻¹⁰ mol m⁻² s⁻¹ (2.4-16 μmol m⁻² d⁻¹), with no specific trend related to solution composition. For the suspensions prepared in pure water, significantly higher rates (∼5.7 × 10⁻¹⁰ mol m⁻² s⁻¹ or ∼49 μmol m⁻² d⁻¹) were determined.Radium uptake by barite was determined by monitoring the decrease of ²²⁶Ra activity in the aqueous solution with alpha spectrometry, after filtration of the suspensions and sintering. The evaluation of the Ra uptake experiments, in conjunction with the recrystallization data, consistently indicated formation of non-ideal solid solutions, with moderately high Margules parameters (W_AB = 3720-6200 J/mol, a₀ = 1.5-2.5). These parameters are significantly larger than an estimated value from the literature (W_AB = 1240 J/mol, a₀ = 0.5).In conclusion, our results confirm that radium forms solid solutions with barite at fast kinetic rates and in complete thermodynamic equilibrium with the aqueous solutions. Moreover, this study provides quantitative thermodynamic data that can be used for the calculation of radium concentration limits in environmentally relevant systems, such as radioactive waste repositories and uranium mill tailings.     

Transcriptome profile of Dunaliella salina in Yuncheng Salt Lake reveals salt-stress-related genes under different salinity stresses

Journal of Oceanology and Limnology - Salt stress is an abiotic stress to plants in especially saline lakes. Dunaliella, a halophilic microalga distributed throughout salt lakes and seas, can...     

The Spectrum and Dips of RE 0751+14: A Joint Evaluation of ROSAT and ASCA Archival Data

Using archival ASCA and ROSAT observations of RE 0751+14, X- ray energy spectra, pulse profiles and the results of pulse timing analysis are presented. The energy spectra are well-fitted by a blackbody model at low energy and a Raymond-Smith model at high energy, together with a partial covering absorber. A fluorescence emission line at 6.4 keV with an equivalent width ∼ 220 eV was resolved for the first time. This revised version was published online in July 2006 with corrections to the Cover Date.     

The potassium abundance in the solar photosphere

High precision center-limb spectrograms of the K i resonance doublet line at λ 7699 Å were used to study the line formation and to determine the abundance of potassium in the solar atmosphere. The LTE assumption is not valid for these lines. Synthetic profiles computed in NLTE reproduce very well the observed center-limb line behaviour and yield log? _K = 5.14±0.10 for the solar abundance of potassium (on the scale of log? _H = 12 for Hydrogen).