Regional geophysics involves both areal surveying and detailed laboratory studies of the physical properties of rock samples.
The petroleum industry requires information on the crust and mantle below the continental shelf to understand fundamental processes such as uplift, basin formation and thermal conditions through geological time.
Discovery of oil and gas
This knowledge is essential when defining areas interesting for petroleum exploration. The information is obtained by integrating seismic interpretation with data from gravity, magnetism, heat flow and petrophysics.
NGU has carried out helicopter surveys of most of the large Norwegian deposits of ore and industrial minerals. New deposits of, for instance, talc, scandium and beryllium are found by helicopter geophysical surveys.
NGU possesses modern instruments for acquisition of geophysical data using airplane or helicopter. In a typical survey, the helicopter is flying 60 metres above the ground with a velocity of 100 km/h. The Earth's magnetic field, electrical conductivity of the subsurface and radioactive radiation from the ground are measured simultaneously.
Aeromagnetic measurementsAeromagnetic measurements have been used since the beginning of the sixties for exploration of oil and gas on the continental shelf. Deep sedimentary basins were discovered in the Norwegian Sea and the Barents Sea. Large petroleum fields have subsequently been discovered in several of these basins. Helicopter surveys have also been used to map radioactive fallout from the Tchernobyl accident, and to map areas with radon risk in uranium-bearing bedrock and overburden.
Important for bedrock mapping
Geophysical maps constitute an important aid in bedrock mapping, especially in areas with a substantial Quaternary overburden. Geophysical interpretation maps reveal the location of zones of structural weakness and deep sub-tropical weathering that are of vital importance in planning new infrastructures such as road- and rail tunnels. Fracture zones are also potential sources for groundwater supply.
Published: 04. February 2008