Kristian Siem-backed Subsea 7 is taking over energy consultancy Xodus Group.
The OSV owner will acquire a 60% holding from Japan's Chiyoda Corporation, which will retain the rest.
The investment "will help the future development and growth of Xodus and complements the existing support from Chiyoda," it said.
Xodus will continue to operate independently of its parent companies, providing engineering and advisory services to the energy industry.
