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The viscosity of gaseous mixturesHunter, Ian Norman January 1989 (has links)
No description available.
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Gas Viscosity at High Pressure and High TemperatureLing, Kegang 2010 December 1900 (has links)
Gas viscosity is one of the gas properties that is vital to petroleum engineering. Its role in
the oil and gas production and transportation is indicated by its contribution in the
resistance to the flow of a fluid both in porous media and pipes. Although viscosity of
some pure components such as methane, ethane, propane, butane, nitrogen, carbon
dioxide and binary mixtures of these components at low-intermediate pressure and
temperature had been studied intensively and been understood thoroughly, very few
investigations were performed on viscosity of naturally occurring gases, especially gas
condensates at low-intermediate pressure and temperature, even fewer lab data were
published. No gas viscosity data at high pressures and high temperatures (HPHT) is
available. Therefore this gap in the oil industry still needs to be filled.
Gas viscosity at HPHT becomes crucial to modern oil industry as exploration and
production move to deep formation or deep water where HPHT is not uncommon.
Therefore, any hydrocarbon encountered there is more gas than oil due to the chemical
reaction causing oil to transfer to gas as temperature increases. We need gas viscosity to
optimize production rate for production system, estimate reserves, model gas injection,
design drilling fluid, and monitor gas movement in well control. Current gas viscosity
correlations are derived using measured data at low-moderate pressures and
temperatures, and then extrapolated to HPHT. No measured gas viscosities at HPHT are available so far. The validities of these correlations for gas viscosity at HPHT are
doubted due to lack of experimental data.
In this study, four types of viscometers are evaluated and their advantages and
disadvantages are listed. The falling body viscometer is used to measure gas viscosity at
a pressure range of 3000 to 25000 psi and a temperature range of 100 to 415 oF.
Nitrogen viscosity is measured to take into account of the fact that the concentration of
nonhydrocarbons increase drastically in HPHT reservoir. More nitrogen is found as we
move to HPHT reservoirs. High concentration nitrogen in natural gas affects not only the
heat value of natural gas, but also gas viscosity which is critical to petroleum
engineering. Nitrogen is also one of common inject gases in gas injection projects, thus
an accurate estimation of its viscosity is vital to analyze reservoir performance. Then
methane viscosity is measured to honor that hydrocarbon in HPHT which is almost pure
methane. From our experiments, we found that while the Lee-Gonzalez-Eakin
correlation estimates gas viscosity at a low-moderate pressure and temperature
accurately, it cannot give good match of gas viscosity at HPHT. Apparently, current
correlations need to be modified to predict gas viscosity at HPHT. New correlations
constructed for HPHT conditions based on our experiment data give more confidence on
gas viscosity.
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Slot Coating Minimum Film Thickness in Air and in Rarefied HeliumBenkreira, Hadj, Ikin, J. Bruce 30 April 2016 (has links)
Yes / This study assesses experimentally the role of gas viscosity in controlling the minimum film thickness in slot coating in both the slot over roll and tensioned web modes. The minimum film thickness here is defined with respect to the onset of air entrainment rather than rivulets, the reason being that rivulets are an extreme form of instabilities occurring at much higher speeds. The gas viscosity effects are simulated experimentally by encasing the coaters in a sealed gas chamber in which various gases can be admitted. An appropriate choice of two gases was used to compare performances: air at atmospheric pressure and helium at sub-ambient pressure (25mbar), which we establish has a significantly lower “thin film” viscosity than atmospheric air. A capacitance sensor was used to continuously measure the film thickness on the web, which was ramped up in speed at a fixed acceleration whilst visualizations of the film stability were recorded through a viewing port in the chamber. The data collected show clearly that by coating in rarefied helium rather that atmospheric air we can reduce the minimum film thickness or air/gas entrainment low-flow limit. We attribute this widening of the stable coating window to the enhancement of dynamic wetting that results when the thin film gas viscosity is reduced. These results have evident practical significance for slot coating, the coating method of choice in many new technological applications, but it is their fundamental merit which is new and one that should be followed with further data and theoretical underpinning.
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Dissolution and growth of entrained bubbles when dip coating in a gas under reduced pressureBenkreira, Hadj, Ikin, J. Bruce January 2010 (has links)
No / This study assesses experimentally the role of gas dissolution in gas entrainment which hitherto has been speculated on but not measured. In this paper, we used dip coating as the model experimental flow and performed the experiments with a dip coater encased in a vacuum chamber in which we admitted various gases. An appropriate choice of gases (air, carbon dioxide and helium) coupled with low pressure conditions from atmospheric down to 75 mbar enables us to test whether gas solubility is a key determinant in gas entrainment. The data presented here track the evolution in time of the size of bubbles of gas entrained in the liquid (silicone oil) which we observed to always occur at a critical speed, immediately after the dynamic wetting line breaks from a straight line into a serrated line with tiny vees the downstream apices of which are the locations from which the bubbles stream out. The results suggest that permeability combining solubility and diffusivity as a single parameter dictates the rate of dissolution when at atmospheric pressure. Helium, despite its comparatively sluggish rate of dissolution/growth into silicone oil was observed to have a more enhanced gas entrainment speed than air and carbon dioxide. Thus, the hypothetical contention from previous work (Miyamoto and Scriven, 1982) that gas can be entrained as a thin film which breaks into bubbles before dynamic wetting failure occurs is not realised, at least not in dip coating. The data presented here reinforce recent work by Benkreira and Ikin (2010) that thin film gas viscosity is the critical factor, over-riding dissolution during gas entrainment. This finding is fundamentally important and new and provides the experimental basis needed to develop and underpin new models for gas entrainment in coating flows.
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Oil and gas properties and correlationsMahdavi, E., Suleymani, M., Rahmanian, Nejat 11 1900 (has links)
No
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Microsystèmes durables de mesures de concentration d'hydrogène utilisant des micropoutres sans couche sensible / Sustainable microsystems for hydrogen concentration measurements using uncoated microcantilevesBoudjiet, Mohand-Tayeb 11 September 2015 (has links)
Ces travaux de thèse tentent de répondre à un besoin de surveillance fiable et durable de la concentration d’hydrogène dans un environnement radioactif. Dans ces travaux, nous proposons l’étude et le développement d’un capteur physique d’hydrogène à base de micropoutres résonantes en silicium. La particularité de ce type de capteur vient du fait qu’il ne contient pas de couche sensible et est donc moins sujet au vieillissement que les capteurs chimiques à base de couche sensibles. Compte tenu de la faible masse volumique de l’hydrogène par rapport à celle de l’air et de la bonne sensibilité des micropoutres résonantes aux propriétés physiques du gaz environnant (masse volumique et viscosité), l’utilisation de micropoutres résonantes pour le suivi de la concentration de l’hydrogène dans l’air est tout à fait possible. L’objectif de ces travaux de recherche est l’amélioration de la sensibilité et de la limite de détection de ce type de capteur. Tout d’abord, une étude des méthodes de suivi de faibles variations de la fréquence de résonance a été effectuée. Ceci a permis de déterminer la méthode ayant le meilleur rapport signal sur bruit, permettant ainsi d’améliorer la limite de détection en termes de variation de fréquence de résonance. Dans une seconde partie, une étude de l’influence de la géométrie et des dimensions sur la sensibilité vis-à-vis des variations de la masse volumique du gaz environnant a été réalisée. A l’issu de cette étude, des critères géométriques et dimensionnels permettant l’optimisation de la sensibilité ont été dégagés. D’autres aspects visant à améliorer les performances (sensibilité et limite de détection) de ces capteurs ont été étudiés, comme l’influence du courant d’actionnement et des tensions de polarisation (actionnement électromagnétique et détection piézorésistive) et l’utilisation des modes supérieurs de résonance. Par ailleurs, l’étude de l’influence des paramètres environnementaux (température et pression) sur le comportement des micropoutres résonantes a été établie. / These PhD research tries to meet a need for a reliable and a sustainable hydrogen concentration monitoring in a radioactive environment. In this work, we propose the study and development of resonant silicon microcantilever-based physical hydrogen sensors. The special feature of this sensor is that it does not contain any sensitive and consequently the reliability is improved, compared to devices with sensitive coating. In view of the low density of hydrogen compared to that of air, and the good sensitivity of a resonant microcantilever to the physical properties of the surrounding gas (density and viscosity), the use of vibrating uncoated microcantilever for monitoring hydrogen concentration in air is therefore possible. The objective of this research is to improve the sensitivity and the limit of detection of such sensors. First of all, a study of methods for monitoring small changes in resonant frequency has been conducted in order to determine the method having the best signal to noise ratio, thus, allowing improvement of its resolution in terms of resonant frequency variation measurement. In a second part, a study of the influence of microcantilever geometries and dimensions on their sensitivity to the gas density variation has been performed. As a result, geometrical and dimensional criteria for optimizing the sensitivity to the gas density have been identified. Other factors in a view of improving performance (sensitivity and detection limit) of vibrating microbeams have been studied, such as the influence of the actuating current and bias voltages (electromagnetic actuation and piezoresistive detection) and using high resonant modes. Furthermore, the study of the influence of environmental parameters (temperature and pressure) on the sensors behavior has been established.
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