"The overall project is the largest liquefied natural gas project that has ever been announced," Ibrahim Ibrahim, deputy chairman of the state-run RasGas Company, said at a press conference in Doha on Thursday.
The project was expected to supply gas principally to the United States, starting in 2008 and continuing over 25 years, according to a company statement.
Ibrahim said the Ras Laffan Liquefied Natural Gas Company Limited III awarded offshore works to the US firm J Ray McDermott Middle East while the onshore deal was granted to Japan's Chiyoda Corporation and France's Technip France Joint Venture.
Ibrahim declined to give a figure for the deals, but said "the overall cost of the whole project is $14 billion."
State-run Qatar Petroleum has a 70% stake in the overall project while ExxonMobil Corporation's subsidiary ExxonMobil Ras Laffan III Limited retains a 30% share.
Qatar's giant North Field, which has proven reserves of more than 900 trillion cubic feet (25 trillion cubic meters), is the third largest in the world.
"The overall project is the largest liquefied natural gas project that has ever been announced"
Deputy Chairman, RasGas Company
It amounts to more than 15% of the world's total proven gas reserves, and is enough to last the tiny Gulf state about 250 years.
Earlier this year, Qatari Energy and Industry Minister Abdullah bin Hamad al-Attiya announced that Qatar has planned to invest $75 billion on a string of massive energy projects by 2012.
Al-Attiya said the projects would make the country the world's largest exporter of liquefied natural gas, with production rising to more than 88 million tonnes in 2012 from a projected 20 million this year.