Abstract

Eleven crude oils and eleven oil-stained core samples from the Blueberry, Dunvegan, Royce, Girouxville East and Eaglesham areas of northwest Alberta and northeastern British Columbia have been geochemically analyzed. The sample set includes three families of oils. The Dunvegan Debolt family is similar to oils derived from the Winnepegosis Formation in Saskatchewan, characterized by a moderate pristane/phytane ratio, significant prominence of the C 34 homohopane biomarker and low concentrations of tricyclic triterpenoids. This family is inferred to have been derived from a source rock deposited under hypersaline, carbonate-evaporite conditions similar to the Winnipegosis Formation source. The Royce Debolt family has many characteristics similar to oils interpreted as having been derived from the Exshaw Formation, including no homohopane prominence, moderate concentration of tricyclic triterpanes and low concentration of the C 24 tetracyclic terpane. The Blueberry Debolt oils are highly unusual in that they are devoid of polycyclic biomarker compounds (steranes and terpanes) but do not appear to be overly mature. These oils are interpreted as having either a third and highly unusual source rock and/or a complex generation, expulsion, migration, entrapment and preservation history.

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