Eni SpA and partners this week may give final approval to a multibillion-dollar plan to develop Kashagan, the world's largest untapped oil field, company officials and analysts said, ending months of delays. The Eni-led project to tap Kashagan in the Caspian Sea may cost $36 billion during the next two decades, analysts at Deutsche Bank AG estimated. Royal Dutch/Shell Group, Exxon Mobil Corp., ConocoPhilips and Inpex Corp. of Japan are also partners. The field, which the partners estimate holds more oil than the U.K. side of the North Sea, is central to Kazakhstan's aim of tripling oil output to 3.2 million barrels a day by 2015. The project has suffered delays, with first production now likely to be in 2008, three years later than earlier planned. ``Eni has been keen to get it done,'' said Caroline Cook, an analyst at Deutsche Bank in Edinburgh, Scotland. ``It's important for all the companies, particularly so for Eni from a credibility perspective.'' Total, Europe's third-largest oil company, said last week that production at Kashagan may be delayed until the spring of 2008. The government has indicated it wants the Eni-led group to pay damages for the delay. Eni spokeswoman Luciana Santaroni declined to comment on the timing of an announcement regarding Kashagan. The Rome-based company is scheduled to report earnings on Thursday and update investors on its strategy Friday afternoon. Payback The BP-led pipeline is scheduled to begin shipping oil next year, carrying crude from BP's Azeri-Chirag-Gunashli field offshore Azerbaijan. Other routes for Kazakh oil include a ChevronTexaco Corp.-led pipeline to the Black Sea and Russian pipelines to the north. Eni and its partners may be able to recover between 9 billion barrels and 13 billion barrels of oil from Kashagan, depending on how much gas is pumped back into the field to boost yields, the company said last October. The project will take almost 18 years to pay back the partners' investment, Deutsche Bank estimated in a research note. That's more than the six to seven year period typical for billion- barrel ventures, Cook said. ``It is a very long time,'' Cook said. ``But then it's