Offshore driller Transocean says it will be retiring four of its offshore drilling units, made up of three drillship and a semi-submersible rig, leading to an impairment of around $520m.
The drillships which are going are the 2000-built Deepwater Discovery, 1999-built Deepwater Frontier and 1999-built Deepwater Millennium. All three of the drillship are currently laid up.
Also going is the 1976-built semi-submersible rig Songa Trym, which Transocean picked up as part of its acquisition of Songa Offshore last year.
Transocean says it will continue to evaluate the competitiveness of its fleet, which could lead to additional rigs being retired.
