OREANDA-NEWS. September 25, 2013. Cnooc Ltd.0883.HK -0.86%, China’s largest listed offshore oil and gas producer by output, said Tuesday its American Depositary Receipts will start trading on the Toronto Stock Exchange, after gaining listing approval from the Canadian stock exchange.

The ADR listing was part of Cnooc’s commitments to win Canada’s approval for the acquisition of Canadian energy firm Nexen Inc. It also pledged to retain all Nexen staff and make Calgary the headquarters of its North American operations.

“The proposed listing of the ADRs on the TSX does not involve a new issuance of shares and will not generate additional funds for the company,” Joint Company Secretary Zhong Hua said in a statement.

Cnooc is now focused on the integration of Nexen after completing the USD15.1 billion purchase in February. The deal–the biggest overseas corporate takeover by a Chinese company–allowed Cnooc to secure oil and gas reserves in western Canada, the North Sea, the Gulf of Mexico and offshore Nigeria.

Cnooc said last year the deal would boost its oil and gas output by about 20% and enlarge its oil and gas reserves by nearly a third.