Norway's Shearwater GeoServices has struck a landmark $600m deal to buy US giant Schlumberger's seismic assets and operations, including its 12-ship fleet.

The companies said the GC Rieber geophysical spin-off will buy WesternGeco, subject to regulatory approvals.

The parties expect to close the transaction in the fourth quarter of 2018.

Shearwater said it will operate the combined businesses as a global, customer-focused and technology-driven provider of marine geophysical services.