Asphaltenes in crude oil

Asphaltenes contain unpaired electrons which can be monitored by ESR/EPR.

Background

Crude Oil contains a heavy fraction called asphaltenes. In a typical oil extraction process, alkanes are used to dilute the crude and bring it to the surface. Asphaltenes, big molecules with polyaromtic features, precipitate from this acyclic diluent forming a thick crust inside the equipment. Aromatic compounds keep asphaltenes in solution.

Asphaltenes contain unpaired electrons and also form complexes with transition metals like vanadium. ESR can detect these species in order to determine the asphaltene content and decide the diluent accordingly.


Application Example: Supramolecular structures

Barskaya et al. 2013

Asphaltenes have been extracted from oil samples from the Akanskoe field in Tatarstan, Russia. The investigation aimed to observe their tendency to aggregate. Three different types of asphaltenes were characterized including molecule structure, viscosity and thermal features.

Results

  • self-organization of asphaltenes was observed

  • variations in oil : precipitant ratios were determined by ESR

  • self-organization only occurs at certain oil : precipitant ratios

 

 

References

  • E. E. Barskaya, A. Z. Tukhvatullina, V. N. Kouryakova, Y. M.Ganeeva, T. N. Yusupova, G. V. Romanov (2013): Journal of Petroleum & Environmental Biotechnology 4, 152-159