Hammerfest Basin Composite Tectono-Sedimentary Element, Barents Sea

Abstract

Abstract The Hammerfest Basin is an east–west-trending graben located between the Loppa High and the Finnmark Platform in the southern part of the Norwegian Barents Sea. Mainly siliciclastic strata of Carboniferous–Cenozoic age cover the Caledonian basement and have a total estimated thickness of 5–8 km. The basin evolved through several tectonic phases: Carboniferous rifting, Late Jurassic rifting, opening of the Atlantic Ocean, Oligocene reorganization of plate movements and post-glacial isostatic rebound. An east–west-trending dome in the centre of the basin developed during the main extensional tectonic event in the Late Jurassic. Horst structures represent the main hydrocarbon traps. Erosional channels on the flanks of the basin represent entry points for Lower Cretaceous sands. For the rest of the Cretaceous and Cenozoic intervals, no significant reservoir sands are expected. The first exploration well in the Barents Sea in 1980 was located in the Hammerfest Basin and by 2019 a total of 45 wells had been drilled in the basin, with 34 classified as exploration wells. The result is 18 oil and gas discoveries, which gives a discovery rate of 53%. Two fields are now in production: the Snøhvit gas-condensate fields and the Goliat oilfield. A total of 340 Msm 3 (2140 Mbbl) recoverable oil equivalents have been discovered. For the middle Jurassic play, the yet-to-find potential may be around 50 Msm 3 , distributed in several small structures in the basin. Following the oil discovery in the Middle Triassic interval in the Goliat structure, and because several of the previously drilled structures only penetrated the Jurassic and the uppermost Triassic section, considerable exploration potential may exist in the deeper Triassic interval in structures with the best reservoir facies. Stratigraphic traps of Cretaceous age may have a moderate petroleum potential, with excellent reservoirs encountered along the flank of the basin. Exploration potential may also exist in Upper Permian sandstones along the southern and eastern flanks of the basin. However, in large parts of the basin, the remaining potential is in the deep structures and, hence, is gas prone.