Platinum Group Element (PGE) systematics in oil source black shales: Implications for petroleum systems

Alex Finlay
Durham University, Earth Science Durham, U.K. [email protected]

     dentifying the source rock of a particular oil has been a challenging yet key problem in petroleum geochemistry for the past 30 years, with no ideal solution. Recent analytical developments allow us to apply PGEs to achieve this aim. Due to their organophyllic nature PGEs are 2 to 10 orders of magnitude more enriched in oil than in the reservoir they reside or any likely crustal rock that the oil migrated through. This makes PGEs very powerful tracers of their original source rocks because the oil composition should mirror source characteristics. The utility of PGEs is enhanced further because of the Os isotope system being embedded within the PGEs. It has been shown that the ¹⁸⁷Os/¹⁸⁸Os compositions vary for black shale of different age and this variation should map onto different oils. Because PGEs share the same chemical characteristics as Re and Os this element group should provide valuable complimentary constraints on the oil source. When PGE and Os isotopes are applied together, this approach could be uniquely powerful in directly linking an oil to it’s source rock and estimating the timing of oil formation.

his study will involve sampling the Jurassic Kimmerage clay and Carboniferous oil shales on the mainland UK. From these samples, PGE values will analysed to investigate there distribution through differing oil source shales. Furthermore North Sea and onshore UK oils, that are thought to be sourced from these units, will be investigated to investigate the feasibility of using the PGEs as an oil source tracer.

 

AAPG Search and Discovery Article #90070 © 2007 AAPG Foundation Grants in Aid