French state oil company BRP (later Elf) established a committee for documentation and information on petroleum (Cedip), with Michel Tenaille as president. He established a subsidiary called Opération Mer du Nord, or Operation North Sea[REMOVE]Fotnote: As part of Operation North Sea, BRP established a Norwegian subsidiary in 1957 under the name Petropar..
This company was to carry out aeromagnetic surveys in these waters which could give an indication of whether oil and gas were to be found. Magnetometric measurements over sea areas could be made from aircraft without informing the authorities. The oil companies wanted positive indications from such measurements before they were willing to invest in seismic surveys as a more expensive but also more accurate form of scientific investigation.
Aeromagnetic surveys were conducted after June 1992 from the Dutch coast, across the Dogger Bank – a North Sea fishing ground off northern England – and to the waters west of Ula. This field lies about 280 kilometres south-west of the Norwegian coast and 65 kilometres north-west of the Ekofisk area.
Measurements were made from aircraft over the northern North Sea between Scotland and Norway in 1962 and 1963. A converted bomber flew bac and forth across the North Sea with a magnetometer on board to record the strength of the magnetic field in the rocks beneath the sea.
On the basis of the data obtained, maps were drawn to show subsea areas where sediments existed and the thickness of these deposits. Gravimetric surveys were also conducted to measure gravitational differences in the sub-surface. Because sedimentary rocks are lighter than other rocks, they exert less gravitational pull. The lower the force of gravity, the thicker the sediments. Geologists and geophysicists were hunting for rocks and geological structures which could have trapped hydrocarbons.Norway proclaims sovereignty over NCS