ef9b01864_si_001.pdf (135.22 kB)
Effects of Aging on Asphaltene Deposit Composition Using Ultrahigh-Resolution Magnetic Resonance Mass Spectrometry
journal contribution
posted on 2019-09-18, 17:40 authored by Estrella Rogel, Matthias Witt, Michael E. MoirIn
this work, the compositional changes of asphaltene deposits
as a function of time were analyzed. It has been demonstrated using
ultrahigh-resolution magnetic resonance mass spectrometry that the
precipitation of asphaltenes is a dynamic process where the composition
of the deposit shows variations that are linked to the exchange of
molecules between the deposit and fluid. The detailed analysis of
the nature of the species that were exchanged during this process
indicates that the species that are more aromatic and richer in heteroatom
molecules are less soluble and become enriched in the deposit as it
ages, as those that are less aromatic with fewer heteroatoms go back
into the fluid. It was also found that the oxygen-containing species
that precipitate are less aromatic and have smaller sizes than those
that do not contain oxygen. This is an indication that for these molecules,
hydrogen bond and dipole–dipole interactions might play a significant
role in their solubility, while for the species that do not contain
oxygen, the driving force for precipitation is aromaticity. These
findings support a previously proposed model that suggests that during
aging, the aggregates become more organized as the more soluble molecules
are expelled, whereas others, the less soluble molecules, are incorporated
into the precipitated material.