Oseberg is a field in the northern part of the North Sea. The water depth is 100 metres. Oseberg was discovered in 1979, and the plan for development and operation (PDO) was approved in 1984. The field was developed in multiple phases and production started in 1988. The Oseberg Field Centre in the south originally consisted of two facilities: the process and accommodation facility Oseberg A and the drilling and water injection facility Oseberg B. A PDO for Oseberg C was approved in 1988 and included an integrated production, drilling and quarters facility (PDQ) in the northern part of the field. A PDO for the gas phase was approved in 1996 and included a facility for gas processing, Oseberg D. A PDO for the western flank, Vestflanken, was approved in 2003 and included a subsea template tied-back to Oseberg B. A PDO for Oseberg Delta was approved in 2005 and included a subsea template tied-back to Oseberg D. A PDO for Oseberg Delta II was approved in 2013 and included two subsea templates tied-back to the Oseberg Field Centre. A PDO for Oseberg Vestflanken II was approved in 2016 and included an unmanned wellhead platform (UWP), Oseberg H, and new wells from the existing G4 template on the western flank. The Oseberg Øst, Oseberg Sør and Tune fields are tied to the Oseberg Field Centre.