Bol’shesyninsky depression: new ideas about structure and petroleum potential according to regional seismic data

The results of regional seismic studies along 32-РС survey line allowed considerable refining the concept of geological structure and petroleum potential of the Bol’shesyninsky depression. They also made it possible to characterise main stages of structural evolution of the region taking into account that it was formed on the south-eastern extension of the Pechora-Kolvinsky aulacogen (the Timan-Pechora Plate). The results of paleotectonic and seismic facies analyses allowed delineating zones of stratigraphic and lithologically screened trap development, as well as their combinations, in Palaeozoic carbonate sequences of the northern regions of the Bol’shesyninsky depression. The promising trend of future geological exploration activities aimed at building up the hydrocarbon raw materials base is delineation of the island shallow-water zone within the Upper Devonian section, which is bordered by organic buildups, together with the accompanying clinoform sequences. Commercial oil bearing capacity of the Denisovsky trough is related to exploration targets of this type. New structural interpretation suggests the presence of exploration targets associated with high-amplitude folds in the foreland parts of thrust plates. Because of inharmonious nature of folding, many of the similar structures are not expressed in near-surface deposits, which makes their identification difficult. Such traps are expected in the regionally oil bearing Devonian-Lower Permian deposits; they are the obvious targets for geological exploration in the Bol’shesyninsky depression