BIG DEAL: China moved toward its biggest overseas energy acquisition, with Chinese oil and gas giant CNOOC Ltd. agreeing to buy Canadian producer Nexen Inc. for $15.1 billion.

THIRST FOR ENERGY: CNOOC and other state-owned Chinese energy companies have increased purchases of oil and gas assets in the Americas as part of a global strategy to gain access to resources needed to fuel China's economy. CNOOC has already invested about $2.8 billion in Canada.

NEXEN NOTES: Nexen operates in western Canada, the Gulf of Mexico, North Sea, Africa and the Middle East, with its biggest reserves in Canadian oil sands.