Asphaltenes

1
Asphaltenes

• Asphaltenes are perhaps most discussed yet least
  understood fraction of petroleum.
• Asphaltenes represent a major component of heavy
  oil and the tar sands which dominate the
  petroleum resource of the world and Alberta.
• Problems
• They are recovered in the laboratory -
  de-asphaltening using alkane solvent e.g
  n-heptane also n-hexane or n-pentane.
• No standards are available for comparison
• Average molecular weight distributions are varied
  and difficult to reproduce
• They are difficult to characterise a major
  component of asphaltene is not GC amenable.

2
Asphaltenes

• Characterise asphaltenes by Size Exclusion
  Chromatography

Shaded area lt550 GC amenable!
Jon Allinson unpublished
3
Asphaltenes

• So far, we have characterised asphaltenes
  according to molecular weight distributions.
• In the absence of suitable asphaltene standards
  molecular weight calibrations using polystyrene
  standards may not give the true representation of
  asphaltene molecular weight distributions under
  the conditions of the Size Exclusion
  Chromatography (SEC). We attempt to address this
  problem

4
Asphaltenes
Waxes are usually co-precipitated / co-occur with
asphaltenes

• Wax analysis
• High temperature Gas Chromatography Flame
  ionisation detection

Standards
South Atlantic oil
Jon Allinson unpublished
5
Asphaltenes

• Our research direction now focuses on studying
  the nature of asphaltenes in the worlds heavy
  oil / tar sand accumulations e.g. Athabasca.
• Improving our knowledge of asphaltenes may lead
  to improved understanding of petroleum
  engineering issues such as wettability and
  emulsification behaviour of crude oils and also
  fluid composition heterogeneity in petroleum
  reservoirs.