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The most common residual viscosity correlation used in the petroleum models is JOSSI et al [1] where the residual viscosity is represented by a polynomial function of 4th degree involving the reduced density ρr ([(η-η*)ξ+10-4]1/4=Σ41=0(aiρri)). Based on this formula, it is possible to predict various uncertainties that can be accumulated and thus alter the performance of viscosity restitution which depends on several factors:The quality of the initial adjustment of the coefficients ai;The precision on the density;The accuracy with which are known the characteristics of the constituents of bases;The validity of the rule of the mixtures selected for the determination of the pseudo-critical coordinates Tcm and Pcm and the equivalent molar mass of the mixture.As far as the results are concerned, we reveal that with the new set of coefficients it is possible to obtain a more preciserepresentation compared to that of JOSSI. The method of JOSSI seems to be especially interesting for the viscosities restitution of systems containing light and close paraffins. However, for some pure substances, the opposite situation could be true. Among the four equations-of-state used, it has been found that the cubic equation-of-stateof PENG and ROBINSON should not be used since we would like to generate the density. Finally, we are not expecting a perfect systematic representation. As demonstrated in our model, if for light alkanes one can expect an average deviation ofless than 10%, for certain pure substances the deviation exceeds 20%.

Measurements of speed of sound were carried out in liquid heptadecylbenzene and octadecylbenzene at pressures from atmospheric up to 150 MPa in the temperature range 303 to 383 K using a pulse technique operating at 3 MHz. Additional density measurements were performed up to 60 MPa. From these measurements, the density was evaluated up to 150 MPa and the isentropic and isothermal compressibilities were determined in the same P and T domain. The results were fitted to a Tait-like equation.

Speed of sound measurements were carried out in liquid tridecylbenzene and pentadecylbenzene at pressures from atmospheric up to 150 MPa in the temperature range from (293 to 383) K using a pulse technique operating at 3 MHz. Additional density measurements were performed up to 60 MPa. From these measurements, the density was evaluated up to 150 MPa and the isentropic compressibility was determined in the same P−T domain.

Experimental determinations versus pressure of the nonlinear acoustic parameter B/A have been conducted for methanol, 1-butanol and 1-octanol in the pressure range 0-50 MPa and temperature range 303.15-373.15 K. These measurements proceed from an experimental technique based on a phase comparison method allowing to measure the change in sound speed with the pressure for an isentropic process. The value of B/A is found to decrease with increasing pressure and seems to be an increasing function of temperature. A comparison with the data determined numerically by the classical thermodynamic method has also been performed.

The speed of sound in the normal hydrocarbonsn- C23H48andn- C24H50has been measured up to 150 MPa in the temperature range (293.15 to 373.15) K using a pulse technique operating at 3 MHz. The data have been used to evaluate various thermophysical properties such as density, and isentropic and isothermal compressibilities up to 150 MPa with the help of additional density measurements performed at atmospheric pressure.

AbstractThe acoustic nonlinearity parameter B/Aalong with intermediate quantities such as the pressure derivative of sound speed and the phase shift were measured in 8 linear alkanes and a series of four isomers of hexane. The influences of temperature and chain length on these quantities were revealed. It was found that the phase shift parameter is more sensitive to molecular structure and temperature than B/Aand that the pressure derivative of sound speed.

The speed of sound in a synthetic and a real distillation cut has been measured up top=150 MPa in the temperature rangeT=(293.15to373.15) K. The synthetic system, which is representative of distillation cuts, is made up of five components with high boiling point temperatures of aboutTb=523 K belonging to essential chemical families found in natural fluids {iso, or n-paraffins, naphthenes, and aromatics (alkybenzene, or alkylnaphtalene)}. The distillation cut comes from the separation of a standard crude oil by distillation aroundT=523 K. The measurements allow the evaluation of various thermophysical properties such as densities, and isentropic and isothermal compressibilities up top=150 MPa with the help of additional density measurements performed at atmospheric pressure.

Ultrasonic velocity measurements were carried out on two ternary mixtures at pressures up to 150 MPa and within a temperature interval of 293 K - 373 K. the first of these two mixtures, which was selected to simulate a distillation cut close to 423 K, is made up (in mass percentage) of 40% nonane, 35% cyclooctane and 25% propylbenzene; the second, made up of 40% undecane, 35% pentylcyclohexane and 25% pentylbenzene has a boiling point of approximately 473 K. The acoustic measurements were then used to characterize the pρT behaviour of these two ternary mixtures in the liquid state. They also provided indirect access to the isentropic and isothermal compressibility coefficients of these mixtures.

A guided falling body viscometer developed in our laboratory for the measure of the viscosity coefficient of liquids (up to 400MPa; temperature range: -10 to 200°C) is described here.This study presents a method developed from experimental results concerning the viscosity of pure linear alkanes (n-C10 to n-C18) and their mixtures in reservoir fluid conditions (up to 100MPa and 20 to 100°C). For such groups, we propose a representative formulation (based on a Vogel type analytical expression and using the same set of empirical coefficients for all compounds) which needs only knowledge of molecular weight.

An apparatus for the measurement of ultrasonic velocity in liquids at high pressures (up to 90MPa) is briefly described. It was used to determine liquid-liquid transitions and vapour-liquid phase boundaries in synthetic mixtures and petroleum fluids. The experimental results were confirmed using a transparent sapphire high-pressure cell. The experimental vapour-liquid equilibria were compared to those calculated from cubic equations of state, in order to emphasize the practical limitations involved in predicting the bubble point of such mixtures.

This paper deals with the restitution of vapour-liquid equilibria in complex mixtures (made up of components commonly involved in the composition of reservoir fluids) using equations of state. Study here is limited to use of the PENG-ROBINSON equation (a cubic form equation) and the mixing rules which are usually associated with it. A simple correlation designed to evaluate the binary interaction parameters kij is proposed for hydrocarbon-hydrocarbon type interactions: carbon dioxide-hydrocarbon type interactions being calculated using NISHIUMI et al.'s correlation. The whole procedure is tested on experimental data for CO2 -C1 -nC16 mixtures at different concentrations.

This paper describes an experimental aaratus for determining liquid-liquid or vapour-liquid phase transitions at high pressure (1 ≤ P ≤ 500 bar). This apparatus was used in the case of ternary mixtures of methane-hexadecanecarbon dioxide, for different concentrations of the components. Pressure-temperature characteristics of the bubble points are given.

The excess viscosity of the binary n-heptane + nonylbenzene has been measured versus pressure (P < 400 bar) and temperature (40°C < T < 80°C) with a falling-body viscometer. The 105 experimental values were adjusted by means of the Bloomfield-Dewan relationship and the Flory's theory without using any adjustable parameter. The average absolute deviation observed on the mixture viscosity is quite good: 5.7%.

This paper presents essentially measurements of ultrasonic speeduand phase transition in a ternary mixture made up of methane, propane, and octane, envisaged in the gaseous state. The ultrasonic-speed measurements were carried out in the temperature range from 293.15 K to 373.15 K and at pressures from the phase boundary up to 100 MPa with a total uncertainty of less than 0.1 per cent. Comparisons between the results and the predictions of several equations of state, widely used in the petroleum industry, are reported and discussed.

Thermophysical properties such as speed of sound, density, and isentropic and isothermal compressibilities have been obtained from ultrasonic speed measurements on two synthetic systems which are representative of distillation cuts with high bubble points (T=520 K andT=573 K, respectively). The first system (composition expressed in mass fraction), (0.40C13H28+0.35C13H26+0.25C13H20), was investigated at pressures from (0.1 to 150) MPa in the temperature rangeT=(293.15 to 373.15) K, whereas the second one, (0.40C17H36+0.35C16H32+0.25C16H26), was investigated at pressures up to 100 MPa in the temperature rangeT=(293.15 to 373.15) K.Copyrigt 1998 Academic Press Limited

This paper reports experimental ultrasonic-speed measurements for two gaseous binary mixtures. The first: (0.90CH₄ + 0.10C₃H₈)(g) was investigated at pressures p from 10 MPa to 70 MPa in the temperature domain from 262 K to 400 K. The second: {0.98CH₄ + 0.02CH₃(CH₂)₆CH₃}(g) was investigated from the phase boundary to p = 100 MPa. The ultrasonic speeds obtained were compared with the values calculated from the Lee-Kesler equation of state. Copyright 1994, 1999 Academic Press

An experimental system for the determination of density, ultrasonic velocity and phase equilibria over a wide range of pressures was developed. Its particular characteristic is that it is well adapted to the investigation of single phase systems including both liquid and gaseous components under normal conditions of pressure and temperature. To extend knowledge of density to pressures above the experimental domain, a numerical procedure based on the use of ultrasound data was adapted from Davis and Gordon's procedure (J. Chem. Phys., 46 (1967) 2650). The aim of this paper is to present results produced using the techniques and method developed in the case of a binary mixture of nitrogen and octane between its saturation pressure and 100 MPa.

Speed of sound measurements have been performed on three mixtures of the ternary system methane + carbon dioxide + normal hexadecane. The systems have been investigated from 12 to 70 MPa in the temperature range from 313 to 393 K. Furthermore, these measurements have allowed the evaluation of the isothermal and the isentropic compressibilities up to 70 MPa from low pressure (<40-MPa) density data.

In the presence of a suitable combination of surfactants (an alkaline metal soap and a medium chain length alcohol, for example), water and oil type organic liquids can form transparent compounds of low viscosity that have been labelled “microemulsions”, with little or no mechanical agitation (spontaneous emulsification) (refs 1–3). Depending on the chemical nature of the surface active agents and the relative constituent proportions, water-in-oil (w/o) or oil-in-water (o/w) systems can be obtained. (Because of the similarity between tertiary solutions of inverted micelles and w/o microemulsions, the term ‘inverted micellar solutions’ has also been suggested4–7.) Microemulsions have been investigated by many scientists interested in liquid state and surface physicochemistry and by many technologists foreseeing numerous applications in industry8,9. It has been suggested9–13that conductivity and permittivity studies could provide, along with other techniques, valuable information about the structure and phase behaviour of microemulsions which are considered to consist of dispersions between a few tens and a few hundreds of angströms in diameter globules made up of an inner spherical core surrounded by a concentric shell of mixed surfactant and cosurfactant1–10. The experiments reported here show that the conductive behaviour of certain microemulsion systems can be accounted for using the percolation and effective-medium theories14–16that have depicted transport properties and continuous metal–non-metal transitions in disordered materials with microscopic inhomogeneities associated with, for example, density, composition15or bonding configuration17fluctuations. This result, which could help in understanding the structural behaviour of micro-emulsions, is considered in connection with the postulated existence in liquid systems of equilibrium bicontinuous structures, a state described by Scriven18as ‘related to ordinary liquids as porous media are to homogeneous solids’.

Winsor IV systems1, or microemulsions2, are macroscopically monophasic fluid transparent compounds made up by mixing water and hydrocarbon in the presence of suitable surface active agents. Depending on composition factors, either water-in-oil (w/o), or oil-in-water (o/w), type systems can be formed. The so-called microemulsions have been intensively investigated3–8because of their potential applications as liquid agents in technical processes (for example, enhanced oil recovery, photochemistry and biotechnology). As they belong to the class of short-range organized fluids, microemulsions also concern condensed matter physicochemists interested in elucidating their structural properties9–12. That critical phenomena can be observed in microemulsions is confirmed by reports that the electrical conductivity variations with water content increasing in certain w/o microemulsions can be accounted for on the basis of the Percolation and Effective Medium theories13–16. It has been suggested15,16that percolative conduction reflects disperse aqueous droplet clustering and interlinking processes predictive of a w/o to o/w transition (phase inversion), involving the formation of equilibrium bicontinuous structures described by Scriven17as being “related to ordinary liquids as porous media are to homogeneous solids”, and modelled by Talmon and Prager18as a random geometry of interspersed water and hydrocarbon domains generated by a Voronoi tesselation. This suggestion is supported by the results reported here, showing that the existence of bicontinuous structures in Winsor IV systems could be identified with the limited composition range separating the w/o and o/w microemulsion regions and over which a post-percolation anomalous conductive behaviour is observed.

The studied predictive model of behavior viscosimetric is the model of K.A. Petersen [1]. The dominant idea of this method is to characterize the viscosity of a fluid from two models taken as a reference in passing through a reduced pressure. The method is corresponding state with two references. This study shows that this method is dependent on the choice of reference and for each of the possibilities of C10/C6H6 and C1/C10 references . The results were investigated for four different weight ratios. It shows that the introduction of an adjusted coefficient does not improve significantly compared to results without adjustment factor, which appears to be the best choice. Regarding the influence of the choice of references, generally the two couples appear suitable but we noted that the choice is not necessary. In the case of mixtures containing at least one aromatic, the results are correct, especially if one takes the ratio of adjustment and our ratio without adjustment compared to that of K. A. PETERSEN[1]. The experimental results of the viscosity exhibit a good agreement with the calculated values. We can predict that the relative improvement is the finding that the introduction of the second body of reference (C10) from the model states corresponding to a reference (C1) of the authors.