Frigg gas field

Frigg gas field is a natural gas field on Norwegian block 25/1 in the North Sea, on the boundary between the United Kingdom and Norway. The field is named after the goddess Frigg. King Olav V of Norway officially opened production on 8 May 1978. Production was closed on 26 October 2004. The field is situated northwest of Stavanger. Operator for the field was the French oil company Elf Aquitaine, which merged and changed name to Total S.A.
Operations were regulated according to an agreement between the UK and Norwegian governments called the Frigg Treaty.
Infrastructural changes were made in three phases:
Geology.
The field was discovered at a depth of by the Petronord group (Elf Aquitaine, Total Oil Marine Norsk, and Norsk Hydro) and the Norwegian State in 1971 with Well 25/1-1 using the Semi-submersible Neptune P 81 in of water. The well was located following interpretation of a 15 by 20 km grid of Reflection seismology lines recorded in 1965. A 5 by 5 km finer grid of seismic lines were recorded in 1969, followed by a 1 by 1 km grid in 1973, combined with four appraisal wells determined the field was in area with a gas column in Lower Eocene sandstones forming an abyssal fan in the Viking Structural basin. The fan structure appears on seismic sections as a low relief Anticline that includes a Flat spot caused by the Density contrast of the gas.