Gullfaks is a field in the Tampen area in the northern part of the North Sea. The water depth is 130-220 metres. Gullfaks was discovered in 1978, and the plan for development and operation (PDO) for Gullfaks Phase I was approved in 1981. A PDO for Gullfaks Phase II was approved in 1985. Production started in 1986. The field has been developed with three integrated processing, drilling and accommodation facilities with concrete bases (Gullfaks A, B and C). Gullfaks B has a simplified processing plant with first stage separation. Gullfaks A and C receive and process oil and gas from Gullfaks Sør and Visund Sør. The Gullfaks facilities are also involved in production and transport from the Tordis, Vigdis and Visund fields. Production from Tordis is processed in a separate facility on Gullfaks C. PDO for Gullfaks Vest was approved in 1993, and for recovery from the Lunde Formation in 1995. An amended PDO for the Gullfaks field, covering prospects and small discoveries, which could be drilled and produced from existing facilities, was approved in 2005. Amendments to the Gullfaks PDO, covering Phase I and Phase II production from the Shetland/Lista deposit, were approved in 2015 and 2019, respectively.