Recognition and Source Correlation of Migrated Hydrocarbons in Upper Jurassic Hareelv Formation, Jameson Land, East Greenland

Abstract

Organic geochemical analysis of an interbedded shale-sandstone sequence from the Upper Jurassic Hareelv Formation, Jameson Land, East Greenland, has revealed oil shows in the sandstones, consistent with petroleum generation and migration. A comparison of the molecular characteristics of extractable material from the sandstones with those of kerogen and bitumen from the shales indicates that the most likely origin of these shows is generation within the shales with expulsion and short-range migration into the sandstones. This conclusion is based on comparisons of biological marker distributions, stable carbon isotopic compositions of extractable material and kerogen, and pyrolysate compositions of kerogen and asphaltenes. Oil from a seep in the Savoia Halvo region south of Jameson Land can be correlated to the Jurassic sandstone oil shows based on similar isotopic compositions and asphaltene pyrolysate distributions. Impregnation of both sandstones and shales throughout the sequence by products generated at higher maturities is considered unlikely, but cannot be ruled out by the existing data. The molecular characteristics of the sandstone hydrocarbons exhibit a striking similarity to those of oils from the mid-Norway region. The similar geologic ages of the Hareelv Formation and the Kimmeridge Clay of northwestern Europe, which is the acknowledged source of the mid-Norway oils, and the geographic proximity of the two regions at the time of early North Atlantic rifting indicate that hydrocarbons from these present-day distant regions have been generated from very similar organic facies, deposited under similar environmental conditions. These results are significant in that in addition to stratigraphic correlation of depositional sequences on both margins of the early rifted North Atlantic, the hydrocarbons generated from source rocks contained in these sequences now can als be geochemically correlated. The results also suggest that Jurassic hydrocarbon source facies deposited throughout the early North Atlantic are geochemically similar, a trait imparted to their generation products.