Extract The early discovery of the Arbroath Field in 1969, and the Montrose and giant Forties fields in 1970, initiated intensive exploration of the Tertiary deep-marine play in the North Sea region. Numerous subsequent discoveries (Fig. 1), including Frigg (in 1971), Maureen (in 1973), Gannet (in 1973), Andrew (in 1974), Pierce (in 1976), Everest (in 1982), Alba (in 1984), Gryphon (in 1987), Nelson (in 1988), Harding (in 1988), Jotun (in 1994), Siri (in 1995) and Merganser (in 1995), demonstrate the success of this play and the geological diversity of Paleocene and Eocene systems present within the region. Although the North Sea Basin is now considered mature, with Cenozoic reservoirs well along their creaming curve (Vining et al. 2005), recent discoveries (e.g. the Catcher Field in 2010) highlight that potential still remains within intensively explored areas such as the Central North Sea, as well as in the less explored regions such as the Atlantic margin and the Norwegian Sea. The importance of these reservoirs is demonstrated by the large proportion of UK production to which they contribute, amounting to approximately 25% of all production from UK oil fields since 1975 on a barrel of oil equivalent (BOE) basis (Fig. 2). Indeed, over time that proportion has increased from 20% of production in the 1970s and 1980s to 30% from the 1990s. ... This 250-word extract was created in the absence of an abstract.