Abstract
Wax content in oil and wax appearance temperature are important factors for simulation of the wax deposition profiles in pipelines. Standard acetone method (UOP method 46–64) or other slightly modified methods of this standard are traditionally used to determine the wax content in the oil. However, in order to determine the wax content at different temperatures, several runs have to be made. This is considered to be time consuming. This paper presents a new method / approach to determine the wax content of oil at different temperatures as well as the wax precipitation temperature from a single run. In this approach a correlation between the change in the density, due to the formation of the solid phase, and the weight fractions of different binary systems was made. For validation purpose of the developed method, a pure normal paraffin (> 95) is prepared from different mixtures of the following components, n-C6, n-CIO, n-C20, n-C22, n-C24, n-C28, n-C32 andn-C36. A comparison between the standard method (UOP Method 46–64) and the developed method shows that the difference between the two methods is within 1–2 wt %. However, several runs are necessary for the standard method to quantify the wax content at different temperatures. While for the developed method the information is obtained from one run. From the same run, the wax precipitation temperature at the operation pressure can, also, be obtained. A good agreement (within 1–2°C) between predicted and measured WPT for defined binary systems above n-C17 is obtained. However, for crude oil systems, it was difficult to establish good correlation with the tested software and it was shown, in general not reported here, to be for most crude oils higher than that obtained by the viscometer.
