Viscosity of liquid hydrocarbon

Ely, J.U. and Tiner, R.L. "Hydraulic Fracturing Method Using Benzoic Acid to Further Increase the Viscosity of Liquid Hydrocarbon," US Patent 3,799,267(1974). 

VISCOSITY OF LIQUID HYDROCARBON MIXTURES AT AMBIENT PRESSURE, 13... 

VISCOSITY OF LIQUID HYDROCARBONS AND THEIR MIXTURES AS A FUNCTION OF PRESSURE, 17 Models that Correct Ambient Pressure Viscosity for Pressure, 18 Models that Incorporate Pressure Implicitly, 18... 

This chapter deals with correlation and prediction methods for the viscosity of liquid hydrocarbons and their mixtures. In particular, the change of viscosity of such fluids with temperature, pressure, and composition is considered. We begin with a brief introduction of terms and definitions, and then discuss the experimentally observed behavior of the viscosity of liquid hydrocarbons as a function of temperature, pressure, and composition. Next, the main types of viscosity models applicable to liquid hydrocarbons and their mixtures are reviewed. We also Indicate the accuracy of several recent viscosity correlation and prediction methods that represent the general types of models in current use. The emphasis in this review is on the recent viscosity models, especially those after 1987, as reviews exist of the earlier methods [1,2], and because the recent methods are usually more accurate. 

The effect of large changes in pressure at constant temperature on the viscosity of various hydrocarbons is shown in Figure 3. There we see that the logarithm of the viscosity of liquid hydrocarbons and hydrocarbon mixtures increases almost linearly with increasing pressure. Alternatively, viscosity can be considered to be a function of density rather than pressure, and this is used in several of the models discussed later. The kinematic viscosity shows similar trends with respect to these variables mentioned above, however its variation with temperature is significantly more linear than dynamic viscosity so that the former is somewhat easier to correlate than the latter. Consequently, some correlations have been developed exclusively for the kinematic viscosity, as will be discussed later. 

There are a large number of models used for the correlation and/or prediction of the viscosity of liquid hydrocarbons and their mixtures. Since there is no exact statistical mechanical or molecular-level theory for liquid viscosity, all of the models available contain some degree of empiricism. Also, there is considerable variation in the structure of these models in that most have been formulated to address only a speeific viscosity estimation problem. For example, some liquid hydrocarbon viscosity models have been proposed only for predicting the viscosity of an undefined petroleum mixture, and their input parameters have been selected accordingly. There are models that use some experimental viscosity data, while others are completely predictive, at least within a class of substances. Some viscosity models are suitable for incompletely defined petroleum cuts, whereas others can be used only for well-defined hydrocarbons and their mixtures. Further, some models include the effects of pressure and dissolved gases on liquid hydrocarbon viscosity, while others are for use only at atmospheric pressure. 

The Viscosity of Liquid Hydrocarbons and Their Mixtures 15 Extension of Corresponding States Methods for Viscosity to Mixtures... 

VISCOSITY OF LIQUID HYDROCARBONS AND THEIR MIXTURES AS A FUNCTION OF PRESSURE... 

Several models that include the effect of pressure on viscosity are outlined herein. For applications at high pressures, one may also require estimates of the viscosity of liquid hydrocarbons and their mixtures with dissolved gases (such as with CO2, Nj, H2S, etc.) because, due to the high solubility of such gases in hydrocarbon mixtures at elevated pressures, there is a very large reduction in the mixture viscosity. Indeed, such behavior is part of the basis for enhanced oil recovery by miscible gas injection. Even though the effect of dissolved gases is beyond the scope of this chapter, some comments about this are included due to the importance of this subject. 

Oliveira, C. M. B. P. (1991). Viscosity of liquid hydrocarbons at high pressures. Ph.D. Thesis, Imperial College, London. 

Chhabra, R. P. (1992). Prediction of viscosity of liquid hydrocarbon mixtures. AIChE J., 38, 1657-1661. 

Ducoulombier D, Zhou H, Boned C, Peyreleasse J, Saint-Guirons H, Xans P. 1986. Condensed phases and macromolecules—pressure (1-1000 bars) and temperature (20-100°C) dependence of the viscosity of liquid hydrocarbons. J Phys Chem 90 1692. 

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