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1.
Water-in-oil mixtures such as emulsions, often form and complicate oil spill countermeasures. The formation of water-in-oil mixtures was studied using more than 300 crude oils and petroleum products. Water-in-oil types were characterized by resolution of water at 1 and 7 days, and some after 1 year. Rheology measurements were carried out at the same intervals. The objective of this laboratory study was to characterize the formed water-in-oil products and relate these properties to starting oil properties. Analysis of the starting oil properties of these water-in-oil types shows that the existence of each type relates to the starting oil viscosity and its asphaltene and resin contents. This confirms that water-in-oil emulsification is a result of physical stabilization by oil viscosity and chemical stabilization by asphaltenes and resins. This stabilization is illustrated using simple graphical techniques. Four water-in-oil types exist: stable, unstable, meso-stable and entrained. Each of these has distinct physical properties. 相似文献
2.
Gerard P. Canevari 《Marine pollution bulletin》1982,13(2):49-54
The formation of stable sea water-in-crude oil emulsions after an oil spill was first reported after the Torrey Canyon wreck in 1967. The problem of handling this stable water (65%)-in-oil (35%) emulsion rather than oil is evidenced in the additional expensive on-site storage requirement as well as the handling difficulty with the viscous semi-solid emulsion. This paper details the results of an R&D program that has established the mechanism for the formation of this emulsion. This insight enabled a specific effective chemical demulsifier to be formulated. A treatment technique was devised that entails injecting the demulsifier into the oil spill emulsion as it is skimmed from the water surface. The emulsion is then rapidly separated into water-free oil and a clean-water phase that can be decanted back into the sea. Full-scale tests were successfully conducted by JBF Scientific Corp. using two types of commercial JBF DIP skimmers in a small concrete lined pond. 相似文献
3.
Oil spilled at sea often forms oil droplets in stormy conditions. This paper examines possible mechanisms which generate the oil droplets. When droplet Reynolds numbers are large, the dynamic pressure force of turbulent flows is the cause of droplet breakup. Using dimensional analysis, Hinze (1955, A.I.Ch.E. Journal 1, 289–295) obtained a formula for the maximum size of oil droplets that can survive the pressure force. When droplet Reynolds numbers are small, however, viscous shear associated with small turbulent eddies is the cause of breakup. For the shear mechanism, we obtain estimates of droplet size as a function of energy dissipation rate, the ratio of oil-to-water viscosity and the surface tension coefficient.
The two formulae are applied to oil spills in the ocean. At dissipation rates expected in breaking waves, the pressure force is the dominant breakup mechanism and can generate oil droplets with radii of hundreds of microns. However, when chemical dispersants are used to treat an oil slick and significantly reduce the oil-water interfacial tension, viscous shear is the dominant breakup mechanism and oil droplets with radii of tens of microns can be generated. Viscous shear is also the mechanism for disintegrating water-in-oil emulsions and the size of a typical emulsion blob is estimated to be tens of millimeters. 相似文献
4.
A.L. Bridi Th.H. Wanders W. Zegveld H.B. van der Heijde 《Marine pollution bulletin》1980,11(12):343-348
During the combatting of oil spills, the handling of the stable sea water in crude oil emulsions called ‘chocolate mousses’, either at sea or on the beach, is often a major problem.
A recent laboratory study of the formation and properties of such emulsions revealed the key roles played by asphaltenes and crystallized wax in their stability.
Viscosity measurements showed that mousses with 70% vol. sea water are thixotropic and may solidify after having been pumped into the hold of a salvage vessel or into a storage tank. During a search for novel chemicals for combatting oil spills we found a type of chemical additive that is effective in preventing the formation of mousses, in greatly improving the pumpability of mousses once formed and in decreasing their water content after recovery or during storage. The additive, designated LA 1834, has been tested successfully in the laboratory, on a semi-technical scale in cooperation with the Netherlands State Waterways Board and in the large-scale clean-up operation after a recent oil spill in Greece. The compound keeps oil from dispersing vertically into the water column, when applied to spilled oil or mousse on a sea water surface and holds promise of environmental acceptability. 相似文献
5.
Physical factors affecting the formation of water-in-oil emulsions (‘chocolate mousse’) from crude Statfjord oil was investigated in the laboratory. Irradiation by visible light and mechanical agitation are shown to be essential. It is suggested that photochemical oxidation of oil components leads to the formation of surface-active, oil-soluble compounds. When these reach a sufficient concentration in the oil, water will be retained within the oil during physical mixing. The plausibility of such a mechanism is investigated further using additions of tetradecanal as an oil-soluble, surface-active agent and β-carotene as an inhibitor of photooxidation. The use of additives to stop ‘mousse’ formation is suggested. 相似文献
6.
《Journal of Volcanology and Geothermal Research》2002,113(1-2):243-258
The viscosity of natural rhyolitic melt from Lipari, Aeolian Islands and melt-bubble emulsions (30–50 vol% porosity) generated from Lipari rhyolite have been measured in a concentric cylinder rheometer at temperatures and shear rates in the range 925–1150°C and 10−3–10−1.2 s−1, respectively, in order to better understand the dependence of emulsion shear viscosity on temperature and shear rate in natural systems. Bubble-free melt exhibits Newtonian–Arrhenian behavior in the temperature range 950–1150°C with an activation energy of 395±30 kJ/mol; the shear viscosity is given by log ηm=−8.320+20624/T. Suspensions were prepared from natural rhyolite glass to which small amounts of Na2SO4 were added as a ‘foaming agent’. Reasonably homogeneous magmatic mixtures with an approximate log-normal distribution of bubbles were generated by this technique. Suspension viscosity varied from 106.1 to 108.37 Pa s and systematically correlates with temperature and porosity in the shear stress range (104.26–105.46 Pa) of the experiments. The viscosity of melt-bubble emulsions is described in terms of the relative viscosity, ηr=ηe/ηm where ηe is the emulsion viscosity and ηm is the viscosity of melt of the same composition and temperature. The dependence of relative viscosity on porosity for magmatic emulsions depends on the magnitude of the capillary number Ca≡G/(σrb−1ηm−1), the ratio of viscous forces acting to deform bubbles to interfacial forces resisting bubble deformation. For inviscid bubbles in magmatic flows three regimes may be identified. For Ca<0.1, bubbles are nearly spherical and relative viscosity is an increasing function of porosity. For dilute systems, ηr=1+φ given by the classical result of Taylor [Proc. R. Soc. London A 138 (1932) 41–48]. For Ca in the range 0.1<Ca<10, emulsions behave as power law fluids and the relative viscosity depends on shear rate (or Ca) as well as porosity. At high Ca (Ca>10) an asymptotic regime is reached in which relative viscosity decreases with increasing porosity and is independent of Ca. Our experiments were carried out for 30<Ca<925 in order to quantify the maximal effect of bubbles in reducing the viscosity of magmatic emulsions relative to single-phase melt at identical conditions of shear rate and temperature. The viscosity of a 50 vol% emulsion is a factor of five smaller than that of melt alone. Rheometric measurements obtained in this study are useful in constraining models of magma transport and volcanic eruption mechanics relevant to transport of volatile-saturated magma in the crust and upper mantle. 相似文献
7.
In situ anaerobic bioremediation using edible oil emulsions will be most effective if the oil droplets can be brought into close contact with the contaminant to be treated. However, uniformly distributing oil in heterogeneous aquifers can be difficult. The impact of injection conditions on emulsion distribution in a three-dimensional heterogeneous aquifer is examined using MODFLOW and RT3D. Emulsion retention is simulated using a rate-limited Langmuir isotherm. Volume and flow contact efficiency are shown to be functions of mass of oil injected, injection fluid volume, well spacing, and injection sequence. Regression equations are developed relating dimensionless scaling factors to expected contact efficiency for area treatment and barriers. Cleanup time for uncontacted zones is estimated using a mobile-immobile zone modeling approach. 相似文献
8.
Abstract Stability analysis is formulated for a two-layer fluid model in which the upper and lower layers are convectively stable and unstable, respectively. With discontinuities in viscosity and conductivity at the interface, the exchange of stability does not generally hold and overstability is possible. A detailed analytical treatment is presented for the case of small viscosity and conductivity in which viscous and conducting boundary layers are formed at the interface. The usual damping effect due to the energy dissipation by viscosity and thermal conductivity exists irrespective of whether the mode is the convection or the gravity wave, but, for larger horizontal wave lengths, the effect of the boundary layer can become more important. The jump in the thermal conductivity in the boundary layer can give rise to overstability of the gravity wave in agreement with Souffrin and Spiegel (1967). The jump in the viscosity provides a self-catalytic action for the unstable flow if the viscosity is assumed to be the nonlinear turbulent viscosity due to the motion itself. The effect, however, is not strong enough to overcome the usual viscous damping. 相似文献
9.
A series of numerical studies on the behaviour of magnetic fields and motions in a spherical body of an electrically conducting incompressible fluid have been carried out. The magnetic field was assumed to be maintained by a given electromotive force inside the body and to continue as a potential field in outer space. In view of the motion an external forcing was taken into account, and boundary conditions were considered which correspond to a stress-free surface. The stability of several steady states has been studied as well as the evolutions starting from unstable states. In this paper a configuration with a poloidal magnetic field and a differential rotation, both symmetric about the same axis, is considered. This configuration is stable only for sufficiently small Hartmann numbers but evolves, if disturbed, in the case of larger Hartmann numbers toward a non-axisymmetric state. In this case the well-known symmetrization effect of differential rotation in magnetic fields is destroyed. 相似文献
10.
Distinguishing oil and water layers by interpreting acoustic logging data with changing well diameters 
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下载免费PDF全文 During surveys, water layers may interfere with the detection of oil layers. In order to distinguish between oil and water layers, research on the properties of well diameters and oil and water layers and their relation to acoustic logging rules is essential. Using Hudson's crack theory, we simulated oil and water layers with different well diameters or crack parameters (angle and number density). We found that when the well radius increases from 0.03 m to 0.05 m, the variation ratio of compressional wave amplitude for the oil layer is less than that for the water layer. The difference of Stoneley wave amplitude between the crack parameters (angle and number density) is greater in the case of the water layer than in the case of the oil layer. The response sensitivity of wave energy is greater for the water layer than that for the oil layer. When the well radius increases from 0.05 m to 0.14 m, the maximum excitation intensity for oil layer is greater than that for the water layer. We conclude that the propagation of an elastic wave is affected by medium composition and well diameter, and the influence has certain regularity. These results can guide further reservoir logging field exploration work. 相似文献
11.
Abstract The linear stability of a non-divergent barotropic parallel shear flow in a zonal and a non-zonal channel on the β plane was examined numerically. When the channel is non-zonal, the governing equation is slightly modified from the Orr-Sommerfeld equation. Numerical solutions were obtained by solving the discretized linear perturbation equation as an eigenvalue problem of a matrix. When the channel is zonal and lateral viscosity is neglected the problem is reduced to the ordinary barotropic instability problem described by Kuo's (1949) equation. The discrepancy between the stability properties of westward and eastward flows, which have been indicated by earlier studies, was reconfirmed. It has also been suggested that the unstable modes are closely related to the continuous modes discretized by a finite differential approximation. When the channel is non-zonal, the properties of unstable modes were quite different from those of the zonal problem in that: (1) The phase speed of the unstable modes can exceed the maximum value of the basic flow speed; (2) The unstable modes are not accompanied by their conjugate mode; and (3) The basic flow without an inflection point can be unstable. The dispersion relation and the spatial structure of the unstable modes suggested that, irrespective of the orientation of the channel, they have close relation to the neutral modes (Rossby channel modes) which are the solutions in the absence of a basic shear flow. The features mentioned above are not dependent on whether or not the flow velocity at the boundary is zero. 相似文献
12.
We measured the water content （0.01% 0.25% w/w） in crude oil emulsions using terahertz time-domain spectroscopy （THz-TDS）. To improve the precision and range of the measurements, we used 1 and 10 mm thick quartz cells. The experiments were performed at 20 ℃ and the THz wave was transmitted vertically to the samples and detected on the other side. The experimental results suggest linear relation for the THz absorption coefficient and the water content of the crude oil emulsions in the observed range. The linear dependence facilitates high-precision measurements of the water content of crude oil. This suggests the potential of THz-TDS in determining the water concentration in crude oil and borehole fluid identification. 相似文献
13.
This paper studies the stability of the central difference method (CDM) for real‐time substructure test considering specimen mass. Because the standard CDM is implicit in terms of acceleration, to avoid iteration, an explicit acceleration formulation is assumed for its implementation in real‐time dynamic substructure testing. The analytical work shows that the stability of the algorithm decreases with increasing specimen mass if the experimental substructure is a pure inertia specimen. The algorithm becomes unstable however small the time integration interval is, when the mass of specimen equal or greater than that of its numerical counterpart. For the case of dynamic specimen, the algorithm is unstable when there is no damping in the whole test structure; a damping will make the algorithm stable conditionally. Part of the analytical results is validated through an actual test. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
14.
《Ground Water Monitoring & Remediation》2000,20(1):94-103
Reagents that enhance the aqueous solubility of non-aqueous phase organic liquid (NAPL) contaminants are under investigation for use in enhanced subsurface remediation technologies. Cyclodextrin, a glucose-based molecule, is such a reagent. In this paper, laboratory experiments and numerical model simulations are used to evaluate and understand the potential remediation performance of cyclodextrin. Physical properties of cyclodextrin solutions such as density, viscosity, and NAPL-aqueous inter-facial tension are measured. Our analysis indicates that no serious obstacles exist related to fluid properties that would prevent the use of cyclodextrin solutions for subsurface NAPL remediation. Cyclodextrin-enhanced solubilization for a large suite of typical ground water contaminants is measured in the laboratory, and the results are related to the physicochemical properties of the organic compounds. The most-hydrophobic contaminants experience a larger relative solubility enhancement than the less-hydrophobic contaminants but have lower aqueous-phase apparent solubilities. Numerical model simulations of enhanced-solubilization flushing of NAPL-contaminated soil demonstrate that the more-hydrophilic compounds exhibit the greatest mass-removal rates due to their greater apparent solubilities, and thus are initially more effectively removed from soil by enhanced-solubilization-flushing reagents. However, the relatively more hydrophobic contaminants exhibit a greater improvement in contaminant mass-removal (compared with water flushing) than that exhibited for the relatively hydrophilic contaminants. 相似文献
15.
S. S. Singh 《Pure and Applied Geophysics》1976,114(4):587-592
Summary Mean soundings over different latitude belts of northern tropical atmosphere have been worked out for four seasons. The soundings thus obtained have been used to compute the mean static stability. The investigation of static stability reveals that the lower troposphere in all the seasons are statically stable and conditionally unstable, and the instabilities are more pronounced in summer than in winter. The role of moist static stability in tropical meteorology has been discussed. 相似文献
16.
Dario Alf G. David Price Michael J. Gillan 《Physics of the Earth and Planetary Interiors》1999,110(3-4):191-210
First-principles electronic structure calculations based on DFT have been used to study the thermodynamic, structural and transport properties of solid solutions and liquid alloys of iron and oxygen at Earth's core conditions. Aims of the work are to determine the oxygen concentration needed to account for the inferred density in the outer core, to probe the stability of the liquid against phase separation, to interpret the bonding in the liquid, and to find out whether the viscosity differs significantly from that of pure liquid iron at the same conditions. It is shown that the required concentration of oxygen is in the region 25–30 mol%, and evidence is presented for phase stability at these conditions. The Fe/O bonding is partly ionic, but with a strong covalent component. The viscosity is lower than that of pure liquid iron at Earth's core conditions. It is shown that earlier first-principles calculations indicating very large enthalpies of formation of solid solutions may need reinterpretation, since the assumed crystal structures are not the most stable at the oxygen concentration of interest. 相似文献
17.
18.
R.J. Morris 《Marine pollution bulletin》1974,5(7):105-109
The natural surface films in the Eastern Mediterranean appear to be badly polluted with petroleum hydrocarbons, and sub-surface oil/water emulsions are also important contributors to the interface chemistry in certain areas. High levels of non-natural hydrocarbons are present in the lipids of some near-surface zooplankton from this regions, suggesting that these animals store and concentrate the pollutant hydrocarbons. 相似文献
19.
An analysis of the mechanism of flow in ice-covered rivers 总被引：1，自引：0，他引：1
Zygmunt Meyer 《Acta Geophysica》2010,58(2):337-355
The paper presents a mechanism of flow of water in an ice-covered river in the case of movable bottom. The analysis is based
upon the principal hydrodynamics equations of turbulent flow in the case of steady uniform motion. It leads to the conclusion
of linear distribution of the turbulent shear stress with depth. It allows to obtain the vertical distribution of velocity
of flowing water under the assumption that at the boundaries (movable bottom and ice) the viscosity of water is greater than
the kinematics viscosity. The relations describing the vertical distribution of velocity of flowing water, as well as the
eddy viscosity coefficient under these conditions, are given. 相似文献
20.
地震作用过程中地震加速度通常呈先增大后减小的特征。利用拟静力法对危岩的稳定性进行分析时,考虑地震过程中地震加速度的变化,对山西太原天龙山危岩体加固工程中的同一危岩体分别以滑塌式和倾倒式破坏模式进行计算,发现地震作用过程中危岩体可能在两种破坏失稳模式之间相互转化。将此问题扩展至一般情况进行计算并讨论,得出如下结论:地震力对危岩体破坏作用的贡献大小不同,通常情况下,地震作用力对危岩的倾覆力矩贡献相对较大;进行稳定性评价时应考虑地震作用过程,以安全系数最先达到1.0的破坏模式作为危岩体的可能破坏模式进行计算;对危岩体进行抗震加固设计时应对加固设计进行多种工况下的校核,保证其在地震作用过程中不同危险状态的稳定性。 相似文献