Hydrocarbon potential of the Bjørnøya West Province, western Barents Sea Margin

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The Bjørnøya West area represents a new exploration province at the central western edge of the Barents Sea Margin. The area includes two sedimentary basins of Tertiary age: the Sørvestsnaget Basin to the south and the Vestbakken Volcanic Province to the northwest. An exploration licence was awarded in the 13th Concession Round, and an exploration well was drilled late summer 1992. So far the geological understanding of the area is mainly based on newly acquired seismic and gravimetric data in combination with shallow coring and correlation to Svalbard. Two tectonic episodes of Palaeogene age are identified in the Bjørnøya West Province. The oldest episode is correlated with the Early Eocene opening of the North Atlantic, and involves both extensional NE-SW-trending normal faults and possibly N-S-trending strike-slip faults. Contemporaneously, large quantities of volcanic rocks extruded on the continental crust close to the young oceanic crust. In Middle to Late Eocene times erosional products from the Stappen High were deposited in the Bjørnøya West area which subsided rapidly at this time. The second tectonic event in the Palaeogene occurred in Late Eocene to Early Oligocene times, mainly following the same zones of weakness as in Early Eocene time. This tectonic episode is responsible for the structuring of the area, and based on seismic mapping a number of structural closures have been identified. In Neogene times, a huge packet of post-rift sediments were deposited at the continental margin, and volumetric calculations indicate that by far the largest volume was deposited in Pliocene-Pleistocene times as a result of glacial erosion on the shelf to the east. As a consequence of the early exploration stage of the area, no precise information exists with regard to reservoir, source and caprock. Based on high-resolution seismic data in combination with correlation to Spitsbergen, the most promising reservoir is prognosed to be Late Eocene coastline progradations from the Stappen High westward into the Vestbakken Volcanic Province. Modelling of seismic brightening indicates the presence of several stacked sandlayers with individual thicknesses of 10–20 m. No oil-prone source rocks of Tertiary age have so far been identified on the Barents Sea Shelf. In the Bjørnøya West Province, sedimentary environments such as Eocene continental margin deposits and possibly continental coal-rich and lacustrine facies are prognosed, and under favourable conditions could have developed oil-prone source rocks. The Late Pliocene-Pleistocene subsidence along the shelf has resulted in late maturation of a potential Tertiary source rock. This timing is regarded to be optimal and increases the hydrocarbon potential of the western Barents Sea Margin.