Navitas had partnered with U.S. oil firm LLOG and Blackstone's portfolio company Beacon Offshore Energy in drilling at the Shenandoah discovery that holds 431 million barrels of oil. Blackstone, through Beacon, is buying LLOG's 31% holding in the $250 million project while Navitas would continue to hold 53%, Navitas said.

It noted that the project is expected to generate $1.13 billion in cash flow for the company. Production is forecast to begin in 2024.

The group recently signed a deal for drilling rig with Transocean.

"Blackstone's and Beacon's capabilities will help complete the project's financing and rapid and successful development," Navitas Chairman Gideon Tadmor said.

(Reporting by Steven Scheer; Editing by Tova Cohen)