P. Costeseque et al., ON THE MIGRATION OF THE PARAFFINS AND ISOPRENOIDS WITHIN CRUDE OILS SUBMITTED TO THERMOGRAVITATIONAL DIFFUSION IN POROUS-MEDIUM, Comptes rendus de l'Academie des sciences. Serie II. Mecanique, physique, chimie, astronomie, 320(4), 1995, pp. 265-271
Vertical stratifications of different hydrocarbons appear within crude
oils submitted to thermal gradients and thus to thermogravitational d
iffusion in porous medium. Concentration gradients, specific to each s
pecies, depend on molecular mass and structural characteristics. The d
ifferential enrichment of n-paraffins in comparison with isoprenoids h
as been measured in the top of porous columns. As the pristane and phy
tane isoprenoids are equally concentrated, the characteristic ratio pr
istane/phytane (a geochemical marker) remained identical.