Ekofisk was Norway's first producing field and is also one of the largest on the Norwegian continental shelf. The reservoir is Cretacious (chalk) with a 300 meter high oil column. It covers an area of 10x5 kilometers, 3000 meters below sea level. It produces both oil and gas.
Production started in 1971. The Ekofisk South development project (2013) contributes to continued production towards 2050.