Shearwater GeoServices would be equally owned by both companies.
Shearwater GeoServices will look to be become an integrated provider of marine geophysical services to oil and gas companies globally. The deal is expected to close by the fourth quarter of 2016.
Beginning with four modern and high-capacity seismic vessels, the firm will provide cost-effective solutions to its clients.
GC Rieber Shipping CEO Irene Waage Basili said: “Over a period of time, we have examined opportunities to establish a new geophysical company, based on the four high-end vessels we currently own.
“In Rasmussengruppen, we have found a partner who shares our view of the opportunities offered by the geophysical market at present, and, equally important, who shares our vision to build and develop Shearwater into a leading player in the industry.”
Rasmussengruppen has vast experience in investing in maritime industries and oil services.
Rasmussengruppen group CEO Dag Rasmussen said: “Shearwater is set up from the start with a modern and cost-efficient fleet, an experienced organisation, and a solid financial platform. Supported by GC Rieber's extensive industry experience, we believe Shearwater will have a unique position in the market that can also consider further strategic opportunities."
GC Rieber Shipping and Rasmussengruppen will own the company 50/50.
Shearwater will take over the four high-capacity seismic vessels: Polar Empress, Polar Duke, Polar Duchess, and Polar Marquis.
The partners will also inject $60m in equity in the form of cash. Terms have been renegotiated with the lending banks for the four vessels.
Under the new terms, there will be a 75% reduction in installments compared with the original repayment profile until June 2019, and an extension of loans terms until 2022 year-end.
Furthermore, Shearwater has agreed on the main terms to purchase the seismic equipment, including streamers and the operative entity, Dolphin Geophysical UK Ltd, which includes the processing business from the former lending banks of Dolphin Geophysical ASA.