Norwegian seismic survey vessel charterer TGS-NOPEC Geophysical is buying the owner of the world's largest 2D data library.

It has backing from shareholders owning 34% of Oslo-listed company Spectrum, it said.

The deal will cement TGS' position as a leading provider of multi-client 2D and 3D seismic data, and realise its ambition of growing exposure towards the South Atlantic.

TGS estimates significant cost synergies of about $20m per year as a result.

The deal values Spectrum at NOK 3.67bn ($418.5m).

Its shareholders will receive a 13.9% stake in TGS.