Calgar, Alberta-based oil and gas company Nexen Inc. announced that it was acquired by China's CNOOC Ltd. for $15.1 billion, sourced said.

The Canadian company released a statement in which it disclosed that the acquisition deal was finalized and that its shareholders will be given $27.50 in cash for each company's share.

The acquisition was announced in July 2012 and was approved by the Canadian regulators in December. Earlier in February, CNOOC escaped from possible failure when U.S. Committee on Foreign Investment cleared the deal. The U.S. was given rights to review the merger since Nexen has exploration and production asset in Gulf of Mexico.

Nexen's chief executive Kevin Reinhart will retain his post at the oil firm, which will be operating as a wholly-owned subsidiary of CNOOC.

The two companies have not divulged what conditions imposed by the regulators in Canada and the U.S. exchange for the approval of the deal.