Characterising Heavy Oil Systems: Oil-Source and Oil-Oil Correlation in the McMurray Formation

Abstract

The Canadian oil sands is the third largest reserve of hydrocarbons in the world. However, this complex petroleum system still maintains a large degree of uncertainty as to oil-source and oil-oil relationships. Detailed evaluation of the chemical composition of heavy oil accumulations provides critical information regarding the temporal and spatial controls on their formation, and the characteristics of the oils, which enables recognition of oil families in the petroleum system. This study conducted an inorganic geochemical investigation of oils extracted from two very closely spaced McMurray Formation cores, from the Suncor Firebag Field, N.E. Alberta. Through the application of trace element geochemistry and rhenium-osmium (Re-Os) geochronology, this study has provided a quantitative determination of the timing of generation for the oils (117 ± 18 Ma) found at East Firebag and has demonstrated the efficacy of using trace metals in the oil column as parameters for between well correlation. In addition, comparison and integration of McMurray Formation Re-Os data with pre-existing data for the Alberta oil sands (Wabasca, Cold Lake, Athabasca, Peace River, Grosmont, Lloydminster and Provost) has enabled an evaluation of oil-oil relationships between the heavy oil deposits across Suncor properties and Alberta. Trace element compositions demonstrate that the McMurray Formation oils share a similar compositional affinity to the Re-Os dataset. Conversely, compositional distinction is noted between these oils and those from Lloydminster, Peace River, Grosmont and Provost. Additionally, oil-source correlation using Re-Os and platinum/palladium indicates that the Gordondale Formation was likely to be the dominant source of the oils analysed by this study. This is despite the sample core location in the eastern part of the basin. Also, examination of trace metal relationships in these oils (V/(V+Ni) and V/Ni) has shown that the source rock organic matter was marine in origin and deposited predominantly in an anoxic environment. In the two McMurray Formation oil columns analysed herein, copper and zinc are shown to provide a robust correlation that highlights three main packages within each oil column (depth equivalent to one another). The results of this study therefore emphasise the importance of inorganic geochemistry for oil characterisation and correlation in heavy oil systems.

AAPG Datapages/Search and Discovery Article #90259 ©2016 AAPG Annual Convention and Exhibition, Calgary, Alberta, Canada, June 19-22, 2016