According to a report in the Australian Financial Review, Sinopec and CNOOC each paid $US615 million for an 8.33% stake in the North Caspian Sea Project in Kazakhstan. The project is expected to start production in two years and is estimated to have reserves of 13 billion barrels of oil equivalent.

The Caspian deal is the latest in a series by Chinese companies looking to secure energy supplies by expanding offshore. It is also the first overseas acquisition for Sinopec.

Last year, CNOOC bought a 5% stake in Australia's brownfield North West Shelf project for $US325 million and later bought a 12.5% stake for $US275 million in the less secure Tangguh gas project in Indonesia.