Migration of hydrocarbons in carbonate source rocks of the Staßfurt member (Ca2) of the Permian Zechstein, borehole Aue 1, Germany: the role of solution seams

The effects of petroleum migration from carbonate source rocks through preferential expulsion of hydrocarbons from stylolites is investigated. This type of expulsion is associated with compositional fractionation. Saturated hydrocarbons and NSO compounds are expelled preferentially. Pristane and phytane show higher relative expulsion efficiencies than n-C17 and n-C18 alkanes. Aromatic hydrocarbons, especially trimethylnaphthalenes, are fractionated by the expulsion processes. Triterpanes and steranes are not fractionated by expulsion from solution seams and could be valuable tools for oil/source rock correlation in carbonate rocks.