Petroleum potential of the Lower Devonian reservoirs on the Chernyshev swell (Timan-Pechora petroleum province)

The Chernyshev Swell is one of the poorly studied and promising areas for the hydrocarbon (HC) exploration in the north of the Timan-Pechora Petroleum Province. Lower Devonian carbonate deposits as part of the Middle Ordovician-Lower Devonian petroleum complex are considered as a priority object for the HC exploration. The study of the Lower Devonian deposits in well core and outcrop showed that the reservoirs were represented mainly by fractured-cavern-pore and cavern-fractured dolomites. The porosity of the rocks reaches 9.3 % with a predominance values in the range of 0.5-1.5%. The permeability values up to 1.0×10-15 m2 are predominant, less often in the range of 1-10×10-15 m2. Such filtration and capacitive properties characterize them as low-capacity and low-permeable reservoirs. The best properties of reservoirs are associated with facies of carbonate shallows, small biostomes and biogerms. The petroleum source rocks are contained in the clay-carbonate unit of the Ovinparma Formation. The OM richest rocks (Corg - 1.08-1.88%) are characterized by the values of (S1+S2) generation potential - 2.18-8.65 mg HC/g rock and hydrogen index HI - 153-432 mg HC/g Corg, which classifies them as medium petroleum source rocks. Thus, the presence of reservoirs, petroleum source rocks and overlapping by the Upper Devonian regional seal is a favorable condition for the formation of HC deposits in the Lower Devonian.