Oslo: CNOOC Ltd, China's biggest offshore energy explorer, and Sinochem Group may separately bid as much as $3 billion (Dh11 billion) for a 40 per cent stake in a Brazilian oil field owned by Norway's Statoil, two people with knowledge of the companies' plans said.

The stake in the Peregrino field off the Brazilian coast may fetch $2.5 billion to $3 billion, the people said, asking not to be identified because the process is confidential. Statoil, Norway's largest oil and gas producer, has told potential buyers to tender an offer by yesterday, they said.

Chief Financial Officer Eldar Saetre said in November that Statoil is considering cutting its stake in Peregrino to reduce risk and build funds for the development of other projects. The Stavanger-based company, which has operations in 40 countries, took control of the oilfield in March 2008 after buying the remaining 50 per cent from Anadarko Petroleum Corp.

John Olaisen, an analyst at Carnegie in Oslo, said fetching $3 billion for a 40 per cent stake would value the field at $7.5 billion. "That's 20 per cent more than we valued it at," he said in an interview.

Kjersti Tvedt Morstoel, a spokeswoman with Statoil in Oslo, declined to comment when contacted by phone on Wednesday night. Jiang Yongzhi, CNOOC's Beijing-based spokesman, didn't respond to calls. Hu Hongjun, Sinochem Group's Beijing-based spokesman, didn't pick up calls made to his office or mobile phone.

Statoil targets crude oil output at Peregrino in early 2011 and will start drilling wells in the first half of next year. The field, 85km off the coast of Rio de Janeiro, has an estimated 460 million barrels of recoverable oil, company spokeswoman Mari Dotterud said on October 20.

Statoil, which has operating rights on about 80 per cent of Norway's oil and gas production, is expanding abroad to counter dwindling North Sea reserves.