Geochemical Studies - 1: Trace Elements in Alberta Crude Oils

Twenty-two trace elements, determined by neutron activation techniques, are reported for 86 conventional crude oils and two crude oils from the Athabasca oil sand deposit, Alberta. When these crude oils are grouped into three families, based on previously studied hydrocarbon characteristics, analysis of variance indicates that S, Se, V, Ni, Br, Co and Zn can be used to differentiate, at a 90 percent confidence level, at least one of the families. These elements may therefore be an additional basis for distinguishing the crude oil families. Further study using multivariate methods are justified.

It is suggested, tentatively, that crude oils with alkaline associated formation waters may be relatively depleted in Na, when compared to those with acidic associated formation waters. The contents of both Zn and V in crude oils may be related to the content of these elements in the source rocks. A geochemical model is presented for the occurrence of Br and I in formation waters and I in crude oils. These three geochemical observations, as well possible use of trace elements for the classification of crude oils into families, may be of value to explorationists and more study is justified.