CNOOC said its planned purchase of a stake in the project had fallen through after the project's existing shareholders vetoed the buy.
The agreement with BG was signed on March 7 for half of the British group's 16.67% stake in the Kazakhstan oil field at a cost of $US615. Three days later, BG entered into a similar agreement with Sinopec group.
However, the acquisitions were subject to a possible rejection by existing partners, global oil giants such as ENI-Agip, ConocoPhillips, ExxonMobil, Inpex, Shell and TotalFinaElf, which had 60 days from the time the preliminary agreements were signed to veto the deal.
The North Caspian Sea project has been described as the largest oilfield find in the last 30 years, with estimated recoverable reserves of up to 13 billion barrels of oil equivalent and the first output is expected in three years.
For CNOOC, the project would have generated cash flow of $US400 million a year, based on development costs of $US2-$US3 a barrel and a similar margin for lifting costs.
