25/2-18 S (Langfjellet) is a discovery in the central North Sea, 20 kilometres east of the Frigg field. The water depth is 120 metres. The discovery was proven in 2016. The reservoir contains oil and gas in Middle Jurassic sandstone in the Hugin Formation, at a depth of 3,500 metres. The discovery is planned developed as a part of a larger development in the area between the Oseberg and Alvheim fields as a subsea tie-back to a new process platform at Frigg-GammaDelta. The plan for development and operation (PDO) is expected to be submitted late 2022.