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 flocculation process and the subsequent
liberation of propane, the solid residue and the liquid extract were
easily recombined with minimal losses by remixing both fractions.
Physical and chemical analysis indicated that the recombined and the
original oil presented similar characteristics in terms of API gravity,
SARA, elemental composition, FTIR, and NMR, but substantial differences
in their rheological behavior. The similarity between original and
recombined oil is also evidenced by 1H DOSY NMR that shows
that sets of aggregates are present in the spectra for both oil samples.