Stylolite characteristics and petroleum geology significance of Ordovician carbonate rocks in Tahe Oilfield

Key words:  Tahe Oilfield  stylolite  reservoir  genetic type  carbonate rocks

Abstract:

By using methods of core observation, thin section analysis, electron probe and Raman spectrum analysis, the stylolite genesis and its petroleum significance in Tahe Oilfield were described based on stylolite characteristics. The results show that there are three kinds of stylolites including bedding, inclined and vertical stylolite. There are three kinds of genetic types for stylolites including compaction, fracturing and pressolution. Compaction is main contribution factor for bedding stylolite, and fracturing is main genetic type for inclined and vertical stylolite. Compaction stylolite or fracturing stylolite are the prerequisite of forming pressolutional stylolite, and pressolutional stylolite is the continuation of compaction stylolite or fracturing stylolite. In Ordovician carbonate rocks of Tahe Oilfield, the stylolites have higher organic matter abundance than matrix, which are also the favorable structure for hydrocarbon generation, migration pathway and advantage to improve physical properties of reservoir.