A New Multicomponent Surface Tension Correlation Based on Scaling Theory

Abstract

Abstract This paper presents a multicomponent surface tension correlation based on scaling theory. In addition to particular exponents employed, the correlation contains two new features: (1) A corresponding-states equation is derived for a correlation coefficient, commonly referred to as a parachor. As a result, the hydrocarbon pseudocomponent parachors can be calculated through this equation, once their pseudocritical properties are estimated. (2) An approach is proposed to calculate the parachors of mixtures. In contrast to the conventional approach, which calculates the mixture parachor via molar mixing of component parachors, this approach first obtains the pseudocrtical properties of the mixture and then employs the corresponding-states equation to calculate the mixture parachor. For various reservoir-fluid related pure components, the corresponding-states equation predicts parachor values to within 1% of those listed in the literature. The surface-tension correlation developed was tested against 45 sets of measured binary surface tension data and four sets of multi-component CO2-reservoir oil surface tension data. Other existing surface tension correlations, i.e. Weinaug-Katz's and Stegmeier-Hough's correlations, are also tested and compared. For the 45 sets of binary data, the average deviation of the new surface tension correlation is 3.71%, which is about 50% smaller than the deviations of the other two correlation cited. In addition, for the CO2-reservoir fluid data, the average deviation is about 7.3%, which is also a significant improvement over the existing correlations. It is worth noting that the surface tension correlation developed does not involve any adjusted parameter and it is also completely compatible with existing compositional numerical simulators.