THE GEOLOGICAL HISTORY AND RESOURCE POTENTIAL OF OVINPARMIAN CARBONATE RESERVOIRS OF DOLGINSKO-PAPANINSKAYA STRUCTURAL ZONE (Timan-Pechora plate

Abstract

One of the most promising oil and gas areas of the Pechora Sea shelf is the Dolginsko-Papaninskaya structural zone. Commercial hydrocarbon content has been proved by exploration drilling for the Carboniferous – Lower Permian carbonate reservoirs at the southern part of the structural zone (Dolginskoye field). However huge oil and gas potential in this region may also be associated with the Ordovician - Lower Devonian complex. Gazprom Neft is conducting systematic exploration and research projects on the Pechora Sea shelf in order to clarify the geological and geophysical parameters of prospective objects. 3D seismic data provided for the three license blocks demonstrate erosion and hypergene transformation of the Lower Devonian carbonate rocks within the uplifts of the Dolginsko-Papaninskaya structural zone. This transformation is a result of the Middle Devonian restructuring. There are local structures where the Lower Devonian sediments are cut off and the regional Timan-Sargaevsky argillaceous seal rocks overlap the carbonate rocks of the Ovinparmian horizon (Lochkovian stage). Secondary transformation of Ovinparmian sediments (dolomitization, dissolution, fracturing etc.) provide formation of high capacity reservoirs. It is spoken in details about sedimentation models and diagenesis transformation of the Ovinparmian carbonate rocks. Hypergene zones are confidently traced according to the materials of seismic facies analysis. The estimated resource potential of the Lower Devonian prospective objects is comparable to the Carboniferous – Lower Permian carbonate complex. The data on probable analogous fields localized in the adjacent tectonic areas are presented in the paper