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Geochromatographic Separation of Organic Tracers Using a Natural Draupne (Kimmeridge Clay) Source Rock Column

The earliest stage of petroleum movement in a natural system is called primary migration. It comprises both the flow of petroleum within a source rock, as well as the discharge of oil and gas into surrounding carrier bed or reservoir units, a process that is termed expulsion. Compared to secondary migration, which has been studied intensely, primary migration so far received comparatively little interest. Previous research has, however, demonstrated that primary migration occurs along with molecular fractionation between asphaltene-/resin-rich source rock bitumens and hydrocarbon-rich oils (Mackenzie et al., 1983; Leythaeuser et al., 1984, 1988). Geochromatographic interactions, i.e. selective adsorption, partitioning into organic matter, ion exchange with minerals, and size exclusion/molecular sieving have been discussed as potential reasons for such fractionation effects (Krooss et al., 1991). Here, we conducted a chromatographic retardation experiment comprising source rock material from mature parts of the Upper Jurassic Draupne (Kimmeridge Clay) Formation to examine the influence of geochromatography on selected organic tracers representing frequently applied organic geochemical proxy molecules. To our knowledge, this was the first time that a chromatographic experiment involved natural, oil-window mature source rock material.