Characterization of heavy crude oils and residues using combined Gel Permeation Chromatography and simulated distillation

Abstract

Characterization of high molecular weight hydrocarbon mixtures such as heavy oil, bitumen, and vacuum residue is essential to design and optimization of the recovery, upgrading, and transportation processes. Characterization provides information about the boiling point and molecular weight distributions. To obtain these information, developing the simple, fast, and consistent characterization method is needed. In this work, for the first time, we combine Gel Permeation Chromatography (GPC) and Simulated Distillation (SD) results to characterize very heavy hydrocarbon samples. In the proposed characterization method, each sample is used individually as a standard sample for GPC calibration by properly matching SD and GPC results. In the other words, use of a standard sample, which is usually polymer compound and not appropriate representative for oil samples, is avoided. The GPC and SD results are coupled to generate the calibration curve that correlates the retention time and molecular weight. Employing the obtained calibration curve for each sample and having the GPC results, the whole molecular weight and boiling point distributions are obtained regardless of the complexity of the extra heavy sample. The proposed characterization method is validated using a known standard sample. Next, this method is applied to obtain molecular weight distribution of several bitumen samples and the bitumen fractions. The developed characterization method provides a tool to find a better understanding of the molecular weight and boiling point distributions of complex mixtures.