Structural Setting and Petroleum Systems
1 December 2014

Following the Edvard Grieg discovery in 2007, an intensive programme of exploration and appraisal drilling has proven recoverable reserves in excess of 420 million Sm3 oil and 18 billion Sm3 gas in reservoirs ranging from Caledonian crystalline basement to Eocene sub-marine fan sandstones. Critical to this success has been the presence of very high quality sandstone reservoirs fringing the southern Utsira High (also known as the Haugaland High) in the Triassic and Middle to Upper Jurassic, and the recognition that Upper Jurassic sourced hydrocarbons could migrate around this high from the southern Viking Graben kitchen area located to the west and south-west. Although shallow to marginal marine sandstones of the Upper Jurassic (Volgian) Intra-Draupne, sourced directly off the emergent Haugaland High, and Upper Triassic Skagerrak sandstones provide the most important reservoirs in this area, significant hydrocarbons have also been proven in the Middle Jurassic (Sleipner, Hugin) and in fractured basement. Upper Permian Zechstein carbonates, Lower Cretaceous, Paleocene and Eocene sandstones and Upper Cretaceous chalks are secondary reservoirs.