Published: Jan 2007
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In this chapter, application of various methods presented in previous chapters is extended to estimate another type of physical properties, namely, transport properties for various petroleum fractions and hydrocarbon mixtures. Transport properties generally include viscosity, thermal conductivity, and diffusion coefficient (diffusivity). These are molecular properties of a substance that indicate the rate at which specific (per unit volume) momentum, heat, or mass are transferred. Science of the study of these processes is called transport phenomenon. One good text that describes these processes was written by Bird et al. . The first edition appeared in 1960 and remained a leading source for four decades until its second publication in 1999. A fourth property that also determines transport of a fluid is surface or interfacial tension (IFT), which is needed in calculations related to the rise of a liquid in capillary tubes or its rate of spreading over a surface. Among these properties, viscosity is considered as one of the most important physical properties for calculations related to fluid flow followed by thermal conductivity and diffusivity. Interfacial tension is important in reservoir engineering calculations to determine the rate of oil recovery and for process engineers it can be used to determine foaming characteristics of hydrocarbons in separation units. As was discussed in Chapter 7, properties of gases may be estimated more accurately than can the properties of liquids. Kinetic theory provides a good approach for development of predictive methods for transport properties of gases. However, for liquids more empirically developed methods are used for accurate prediction of transport properties. Perhaps combination of both approaches provides most reliable and general methods for estimation of transport properties of fluids. for petroleum fractions and crude oils, characterization methods should be used to estimate the input parameters. It is shown that choice of characterization method may have a significant impact on the accuracy of predicted transport property. Use of methods given in Chapters 5 and 6 on the development of a new experimental technique for measurement of diffusion coefficients in high-pressure fluids is also demonstrated.