The clearance means a waiting period required under a 1976 US anti-trust act will be terminated early. Cameron stockholders must still approve the deal, which was announced in August this year.
A special meeting of stockholders regarding the merger is scheduled for 17 December.
Schlumberger and Cameron expect the deal to close in the first quarter of 2016. Schlumberger said from the beginning that it has no intention to sell off any part of Cameron, which specialises in building blowout preventers and other subsea equipment.
