John Fredriksen-backed Seadrill has formed a new joint venture with Angolan oil company Sonangol to operate drillships.
The 50/50 partnership with Sonangol affiliate Empresa de Servicos e Sondagens de Angola will run four vessels, restructured Seadrill said.
They will focus on "opportunities" in Angolan waters.
Each company will bareboat charter two vessels to Sonadrill.
The Seadrill ships will come from its existing owned or managed fleet.
The Sonangol vessels are the 61,000-dwt Libongos and Quenguela, both seventh-generation high-spec ultra-deepwater units under construction at DSME in Korea.
They are expected to be delivered in the first half of this year.
Seadrill will manage the delivery and mobilisation to Angolan waters under a separate agreement with Sonangol.
It has also signed a management and operation contract with Sonadrill for five years initially.
Seadrill CEO Anton Dibowitz said: "We are excited to have been selected by Sonangol to manage their newbuild drillships and to partner with them in pursuing opportunities in this important deepwater basin.
Sonadrill will give us the opportunity to gain incremental access to a market that is expected to show significant growth over the next years, further strengthen our relationship with key customers and provides an attractive opportunity to continue expanding our fleet of premium ultra-deepwater rigs."
