|
On Creating Standards in Asphaltene and Petroleum
Colloids Research
At the recent 4
th International Conference on “Petroleum
Phase Behaviour and Fouling,” many sentiments were expressed
that research progress in this field is hindered by a number
of issues related to the complexity of petroleum fluids and a
lack of “research standards” in terms of how asphaltenes and
other colloid-forming materials in petroleum are obtained and
analyzed. As a result, a number of researchers agreed to
initiate and maintain a forum for discussing these issues.
This brief synopsis is intended to help summarize some of
those issues.
One key challenge to progress in asphaltene research is the
variety of ways in which asphaltenes are obtained and defined.
Common definitions of asphaltenes revolve round those
materials in petroleum fluids which are “strong
solvent-soluble” and “poor solvent insoluble.” This
“solubility class definition” clearly lends itself to a host
of possible means of implementation. Perhaps the most common
pair of “strong” and “weak” solvents used in asphaltene
isolation are toluene and n-heptane, but even with this pair
of solvents, there are many possible ways to conduct the
isolation, and Alboudwarej et al. (2002) have enunciated many
of these issues. Identifying a standard and acceptable method
for isolating asphaltenes from crude oils, bitumen, and other
petroleum fluids is one goal of this web forum. A related (and
perhaps more ambitious) goal is to potentially identify
agreed upon methods of fractionating asphaltenes into
subfractions for further characterization and analysis in
efforts to identify those functional properties of asphaltenes
which confer the most important colloidal properties, e.g.
adsorption at interfaces, consolidation, emulsion
stabilization, ggregation, deposition, and the like.
A second key challenge to progress in asphaltene research
is agreement on the most appropriate means and methods to
establish molecular structure and molar mass of asphaltenes.
While it is now well appreciated that the distribution of
asphaltene monomer molar masses extends to quite low
values (500-1,000 amu) for any (if not all) petroleum fluids,
the best means of elucidating molecular structure and a
tandard method for measuring “average” molar mass appears to
not be well agreed upon.
Certainly, this is an active area of research and much good
investigation is currently ongoing. Nonetheless, some
agreement among the community of scholars pursuing this
research could assist in more rapid progress as comparative
studies among labs becomes more common.
We hope this brief synopsis of two of the key challenges
can lead to some healthy dialogue and a fruitful interaction
at the upcoming 5 th International
Conference to be held in Banff Canada in June of 2004. Please
understand that the intent of this forum is not to limit or
direct the way in which asphaltene researchers approach their
work, but rather to create a dialogue and some means of
arriving at directly comparable results among labs. One
outcome might be that groups that opt to perform
characterization and analyses that are “non-standard” continue
to do so but add an additional analysis in the “standard” or
agreed-upon way to provide a mapping of their results that all
can appreciate and understand.
Sincerely,
Peter Kilpatrick
Professor and Department
Head
Department of Chemical Engineering
North Carolina
State University
Raleigh, North Carolina
27695-7905,USA | 