This document is an expanded abstract.


One of the remaining challenges in the oil industry is the lack of applied modeling tools capable to provide accurate information on the thermodynamic and transport properties of fluids in a consistent framework. While numerous correlations and equations are available in process simulators, they can lead to inconsistencies when used separately to describe a whole set of properties of multicomponent mixtures, particularly at high pressure conditions.

The goal of this contribution is to overcome this issue by presenting a molecular-based equation of state, named soft-SAFT, to simultaneously describe thermodynamic and transport properties of oil-related systems. The equation presented is based on statistical mechanics and has been extended to calculate transport properties by adding different the Free-Volume Theory, relating all the different properties in a consistent manner. This allows an accurate evaluation of density, phase equilibria and viscosity of fluids and mixtures in a wide range of conditions. The formulation includes a series of molecular parameters that are related to the chemical structures and the molecular weight of each compound, allowing the possibility of extrapolating at different working conditions, as well as describing similar molecules when experimental data are not available. With this integrated approach, all the data is consistent and there is no need to use additional independent correlations.


Thermophysical properties affect most aspects of oil plant design and operation. Consequently, property data and predictive methods are basic information for the process design. In this regard, process simulation has become the main tool for the development, design, scale-up and optimization of chemical processes. However, current simulators commonly use different equations of state for phase equilibrium properties, typically restricted to pressure-volume-temperature data. In addition, information related to derivative, interfacial and transport properties is normally obtained by means of semiempirical correlations. The use of integrated equations able to provide accurate values of a group of thermophysical properties for practical applications is of high interest in order to have a common framework, avoiding data inconsistencies.

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