New Targets for Petroleum Exploration in the North Urals Thrust Belt

Abstract

The North Urals thrust belt is a vast (18,000 km[sup 2]) frontier exploration area in the eastern part of the Timan-Pechora basin in the northeastern corner of Europe. The existence of a 12-14-km-thick sedimentary cover with proven reservoir and source rocks, the presence of the supergiant Vuktyl gas and condensate field, and petroleum industry infrastructure make this area one of the most attractive for oil and gas exploration in Russia. Structurally, the North Urals thrust belt represents a strongly deformed margin of the Pechora plate deformed due to continental collision in the Late Paleozoic. Interpretation of recently acquired seismic profiles, coupled with surface geology and bore-hole information allows one to propose a new structural model of the area. This new interpretation suggests extensive occurrence of blind wedge-shaped duplexes or triangle zones, which form a buried thrust belt front. They were wedged into the sedimentary section of the foreland basin along Lower Permian shales which provided an effective level of delamination. The 4-6-km-high frontal antiforms consist of 3-4 stacked sheets of carbonate-dominated Ordovician-Lower Permian beds. One of the blind thrust sheets contains the main gas pool of the Vuktyl field. This structural model differs significantly from the previous ones which implymore » that all foreland-vergent thrusts reach the erosional surface and it provides favorable conditions for petroleum accumulation. The frontal anticlines of stacked thrust sheets concealed by a [open quotes]passive roof[close quotes] monocline of the Permian Molasse section are considered to be the primary exploration targets. Excellent reservoir properties of these rocks have already been proven at the nearby Vuktyl field.« less