(580e) A Method to Determine the Solubility Curve of Wax in Crude Oil by Centrifugation and High-Temperature Gas Chromatography

A method is proposed to determine the percent of precipitated wax in the crude oil at different temperatures using centrifugation and HTGC analysis on the crude oil and the centrifuged cake. The cake consists of precipitated wax and entrapped liquid oil. Two relationships are used to get the solid fraction in the cake and cooled crude oil. One is the ratio of solid fraction in the cake to the one in the cooled crude oil can be described by the ratio of mass of crude oil used for centrifugation to the mass of the cake. Another relationship is related to the fraction of light components in cake/crude oil. The light components of carbon number lower than a unique number will not present in solid phase according solid-liquid equilibrium. For the light component, its fraction in cake/crude oil, which could be obtained by HTGC analysis, can be described by its fraction in liquid part and the solid fraction in cake/cooled crude oil. Coupling these two relationships, the solid fractions in the cake and cooled crude oil can be obtained. It reveals that up to 94% liquid entrapped in the centrifuged cake. The newly developed solubility curve of wax in crude oil is used to simulate wax deposition experiments and the results are discussed.