The U.S. Department of Justice granted unconditional approval on Wednesday to the proposed merger between Schlumberger and Cameron International.
Schlumberger agreed in August to acquire Houston-based equipment firm Cameron in a stock and cash transaction worth about $14.8 billion.
The DOJ also granted the companies early termination of the waiting period required by the Hart-Scott-Rodino Antitrust Improvements Act of 1976.
The closing of the proposed merger is still subject to approval by Cameron stockholders and the satisfaction or waiver of the other closing conditions contained in the merger agreement between Schlumberger and Cameron.
A special meeting of Cameron stockholders is scheduled for December 17, where stockholders will consider and vote on the proposed adoption of the agreement and merger plan.
Schlumberger and Cameron expect to close the merger in the first quarter of 2016.
The companies said they will continue to operate as separate and independent companies and continue to serve their respective customers until the merger is complete.
Under the terms of the agreement, Cameron shareholders will receive 0.716 shares of Schlumberger common stock and a cash payment of $14.44 in exchange for each Cameron share.
Houston-based Schlumberger expects to realize pretax synergies of $300 million in the first year and $600 million in the second year after the acquisition.
On a pro forma basis, the combined company had 2014 revenues of $59 billion.