ABSTRACT

Crude oils and condensates from the Beaufort-Mackenzie Basin have been analyzed chemically in order to establish a genetic classification scheme. The chemical properties of crude oils and condensates are a function of thermal and biological processes as well as the type of source organic matter. By examining many chemical parameters, the effects of biodegradation and primary or secondary thermal alteration have been circumvented as much as possible.

The analytical data used include the following: 1) fractionation into saturates, aromatics, NSO's and asphaltenes; 2) pristane/phytane ratio; 3) C₁₅+n-alkane distribution; 4) ¹³C of saturate and aromatic fractions; 5) distribution of 26 compounds in the gasoline range (C₅-C₈); and 6) distribution of groups of aromatic compounds. The results of the chemical analyses indicate that several oils (Imnak, Kugpik and Mayogiak) belong to one family and were derived from the Boundary Creek/Smoking Hills Formation. The gasoline-range data indicate that the Tertiary condensates from Taglu, Niglintgak and Kumak are related and have properties similar to those of the Lower Cretaceous Parsons/Siku condensates. The similarity of these two groups of condensates may be due to higher land-plant (herbaceous) debris being the main source organic-matter type in both cases. That they do in fact have separate sources is supported by the stable carbon isotope data. Another group consists of the Ivik oils, which may have a distinctive source or may be internally correlative because of the extensive biological alteration they have undergone. On the basis of the aromatic data, the Taglu and Kumak oil samples tended to group with the Ivik oils and, to a lesser extent, with the Adgo oils, suggesting a common Tertiary source followed by extensive biodegradation of the latter two groups.