Improved characterization of the plus fraction for wax precipitation from petroleum fluids

Abstract

ABSTRACTWax formation is a serious problem in the gas and oil industry because it can block oil production facilities and transportation pipelines. It is, therefore, of great importance to have a reliable tool to predict wax formation under various operational conditions. The hydrocarbon plus fractions that comprise a significant portion of naturally occurring hydrocarbon fluids create major problems when determining the thermodynamic properties and the volumetric behavior of these fluids by equations of state. In this work, an effort has been made to further improve the characterization of the plus fraction, splitting the plus fraction into a single carbon number (SCN) and generating the mole fraction, on the basis of the relationship between the three‐parameter gamma distribution, experimental molar fraction, molecular weight, and SCN data obtained from literature and industrial contact. The three‐parameter gamma distribution is used to fit the trend of the computational analysis. The method has been used to predict wax appearance temperatures (WATs) for a great number of systems and to compare with some methods generated previously. The average deviation of the calculated WAT is 1.47 K for the system with the experimental data. There are some correlations generated to calculate the physical–chemical properties as a function of SCN. Those correlations have been originally developed to work with light oil. The developed approach, along with some of the correlations, is tested for calculating WAT to identify the applicability in this work. © 2013 Curtin University of Technology and John Wiley & Sons, Ltd.