Backthrust play of the Chernyshev swell, Timan-Pechora Basin: Reentry into a legacy exploration site based on multidisciplinary study

Abstract

We have developed a new interpretation of the Povarnitsa High, located in the southern part of the transition zone between the Chernyshov swell and the Kosyu-Rogov trough in the Polar Urals foreland. Petroleum exploration in this area took place in the 1980s and resulted only in an uneconomical oil deposit. Reprocessing and reinterpretation of vintage data and a newly acquired 3D seismic survey along with nonseismic geophysical data provided new insight into the geologic setting of the area. It found a subthrust extension of the Povarnitsa High, overlain by a backthrust sheet floored by upper Ordovician evaporites. This backthrust sheet interpretably resulted from the squeezing of the salt diapir during the late Permian contraction. Stratal patterns of the Silurian-Carboniferous section adjacent to the salt structures suggest early precontraction initiation of the halokinetic deformation, which influenced the distribution of reservoirs such as reefs and oolites. We consider the salt-cored subthrust structural culmination a principal hydrocarbon prospect. It includes multiple reservoir-seal pairs in the Silurian-Permian section at depths ranging from 1 to 4 km. The updated structural model of the Povarnitsa High area suggests that the vintage wells penetrated prospective intervals at the periphery of the closure approximately 1 km downdip from the subthrust crest of the prospect.