The Lower Devonian (Ovinparmian) reservoir: Prospects in the offshore part of the Timan-Pechora petroleum basin

Abstract

The offshore part of the Timan-Pechora petroleum basin is one of the most promising areas to search for new petroleum accumulations. The commercial potential of the Carboniferous-Lower Permian play has already been proven by exploratory drilling in the Dolginskoye uplift, whereas the Prirazlomnoye field has been in production since 2013. However, significant petroleum resources in this area may be confined to the Ordovician-Lower Devonian play. The purpose of the study is to evaluate the potential of the Lower Devonian (Ovinparmian) reservoirs within the Pechora Sea shelf based on new geologic and geophysical data. We identified multiple prospects within the Dolginsko-Papaninskaya structural zone and estimated its resources. The potential of the Lower Devonian within the study area is comparable with that of the Carboniferous-Lower Permian play. Based on the new 3D seismic data performed in three offshore license blocks, we identified several unconformities, where the Timanian-Sargaevian regional seal onlaps carbonate rocks of the Ovinparmian horizon (Lochkovian stage, Lower Devonian). We hypothesize that due to the Middle Devonian structural deformations, the Lower Devonian carbonate deposits have been exposed to subaerial erosion and surface and subsurface karst. Diagenetic alterations of the Ovinparmian sediments (i.e., dolomitization, dissolution, and fracturing) are favorable for the development of high-porosity reservoirs. In our study, we consider some sedimentation, diagenesis, and catagenesis models of the Ovinparmian carbonates. Furthermore, we designed an exploration program with a view to further study the Lower Devonian reservoirs.