Determining the wax content of crude oils by using differential scanning calorimetry

Abstract

By the use of differential scanning calorimetry (DSC), a new method to measure the wax content of crude oil has been developed. In this paper, the wax content of a crude oil is proposed and proved to be the Q (total thermal effect of wax precipitation in sample) ratio of the crude oil and its corresponding wax obtained by using standard acetone method, i.e. Q oil/ Q wax. For the 14 studied crude oils with the wax content ranging from 1 to 27 wt.%, the wax contents determined by the presented method are in good agreement with those determined by standard acetone method, with an absolute average deviation of only 0.82 wt.%. This method has an advantage over reported DSC methods in which the exact dissolution or precipitation enthalpy of wax is a must. It is also found that the wax contents determined by either of the two methods show good linear relationship with the total thermal effect Q oil, with the correlation coefficients over 0.96. According to the empirical correlations, the wax content of a crude oil can be easily determined by using the DSC total thermal effect Q oil. In addition and more significantly, the new method can be applied to improve the accuracy in determining the amount of precipitated wax in a waxy crude oil at different temperatures.