Characterization of the Solid Residue and the Liquid Extract Separated by Propane-Induced Crude Oil Fractionation

Abstract

Following a previously reported experimental procedure, a heavy petroleum sample was fractionated by mixing a predefined volume of oil with liquid propane above its saturation pressure at different propane/oil ratios. The separated fractions, considered two mutually saturated liquid phases in equilibrium at p and T separation conditions, were denominated solid residue and liquid extract and were characterized by chemical and spectroscopic methods including elemental compositional and SARA analyses, FTIR, and NMR. The results show that the amount yielded or produced increases for the solid residue and decreases for the liquid extract as the propane/oil ratio increases and that the four SARA components are present in both fractions, independently of the propane/oil ratio used in the fractionation process. The data also indicate that polar components are present in the liquid extract even at the highest dilutions that correspond to rather low solubility parameters. Complementary results show that after the f...