The Sverdrup Basin, Arctic Canada Has Many Analogues to the Barents Sea's First Permian Oil Discovery

Abstract

Abstract

The 2013 Gohta oil discovery is the first significant discovery in the Permian succession of the Barents Sea. The oil pool lies beneath a sub-Early Triassic angular unconformity, suggesting block faulting and tilting prior to the onset of Triassic sedimentation. The reservoir rocks are Permian spiculitic cherts and heterozoan carbonates of shallow origin that accumulated at a time of cool oceanographic conditions. The porosity may be the result of extensive sub-Triassic subaerial karsting. The seemingly unique set of attributes of the the Gohta Discovery has been observed at a number of localities in the Canadian Arctic Archipelago. The Sverdrup Basin was adjacent to the Barents Sea area throughout its Late Paleozoic-Mesozoic history prior to the break-up of Pangea. The succession is thicker than that of the Barents Sea, owing to greater subsidence rates, but its stratigraphic sequences are identical. Permian spiculitic chert is widespread, especially in the Late Permian succession, when carbonates were all but eradicated. The loss of carbonates can be in part associated with cooler oceanic conditions and possibly to upwelling-enhanced ocean acidification along NW Pangea. Late Permian organic-rich shales locally interfinger with the chert and may constitute a source rock. Porosity is unusually high in Late Permian chert. Large carbon isotopic depletion in carbonate material beneath the sub-Triassic unconformity suggests extensive meteoric leaching occurred. The sub-Triassic unconformity is widespread and one of the most significant in terms of base level drops in the history of the basin. The unconformity is also locally angular and associated with basal conglomerates of Permian pebble to cobble spiculitic chert clasts. An angular relationship is observed on northern Ellesmere and Axel Heiberg islands. From these observations we conclude the set of conditions that led to Gohta is a genuine play worth exploring both in the Barents Sea and in the Sverdrup Basin.

AAPG Datapages/Search and Discovery Article #90260 © 2016 AAPG/SEG International Conference & Exhibition, Cancun, Mexico, September 6-9, 2016