Petroleum source rock identification of United Kingdom Atlantic Margin oil fields and the Western Canadian Oil Sands using Platinum, Palladium, Osmium and Rhenium: Implications for global petroleum systems

Abstract

This study demonstrates that petroleum and source rocks are enriched in Pt and Pd to the ppb level, and that the 187Os/ 188Os composition coupled with the Pt/Pd value permits the fingerprinting of petroleum to its source. Oils from the United Kingdom Atlantic Margin (sourced from the Upper Jurassic Kimmeridge Clay Fm.) as well as source rock samples have been analysed for Pt and Pd. When the Pt/Pd value is compared with 187Os/ 188Os (calculated at the time of oil generation; Os g) the values from both the known source and the oils are similar, demonstrating that they can be used as an oil to source fingerprinting tool. This inorganic petroleum fingerprinting tool is particularly important in heavily biodegraded petroleum systems where traditional fingerprinting techniques (e.g. biomarkers) are severely hampered, e.g. the world's largest oil sand deposit, the West Canadian Oil Sands (WCOS). This has caused the source of the WCOS to be hotly debated, with no present day consensus between inputs from potential source units e.g. Exshaw and Gordondale Fms. 187Os/ 188Os and Pt/Pd fingerprinting of the oil sands shows that the majority of the petroleum have similar 187Os/ 188Os and Pt/Pd values, supporting the hypothesis of one principal source. Analysis of the potential source rocks establishes that the principal source of the oil sands to be from the Jurassic Gordondale Fm., with a minor Exshaw Fm. input. Thus, the combination of previously pioneered Re–Os petroleum geochronology with 187Os/ 188Os and Pt/Pd values of petroleum permits both a temporal and spatial understanding of petroleum systems.