Areas of operation: Only about 30 per cent of Nexen's production comes from its Canadian operations, with the rest coming from offshore platforms in the North Sea, Gulf of Mexico and West Africa.
The Buyer: CNOOC Ltd. is China's largest offshore oil and gas producer and is one of the largest oil and gas exploration and production companies in the world. At the end of 2011, it had 909,000 barrels of oil equivalent per day of production.
Its Beijing-based parent, China National Offshore Oil Co., operates directly under the State-owned Assets Supervision and Administration Commission of the State Council of the People's Republic of China.
CNOOC Ltd. shares trade on Hong Kong and New York stock exchanges.
The Offer: On July 23, Nexen announced it had accepted CNOOC Ltd.'s all-cash offer of $27.50 per share, worth $15.1 billion. In a circular to shareholders a month later, Nexen revealed it had rejected two earlier CNOOC offers as too low.
The Premium: 61 per cent over Nexen's closing share price on the trading day before the deal.
Partnership history: CNOOC and Nexen had a relationship well before they announced their deal. In 2011, CNOOC acquired Opti Canada Inc., Nexen's beleaguered partner in the Long Lake oilsands project and the two have been working together on that project since.
Later in 2011, CNOOC and Nexen formed a joint venture in the Gulf of Mexico.
Around the same time, Nexen also agreed to sell a 40 per cent interest in some of its northeastern B.C. shale natural gas lands to a Japanese-led consortium.