Its oil industry — and partnerships with some the world's biggest firms — has existed for nearly a century. Iran sits on the second-largest known reserves after Saudi Arabia, and its known natural gas reserves are second only to Russia.

Iranian experts also are involved in oil projects abroad in places including Turkmenistan, Venezuela and Libya, and Iran has developed some smaller fields before.

Yet, "if Iran does it, things will take longer and the cost might be greater," said Manouchehr Takin, an Iranian oil specialist at the London-based Centre for Global Energy Studies.

Supporters argue "this is the way to learn — by doing," he noted.

But that will take time. Iran is trying to boost its production from the current 4.2 million barrels a day to about 5 million barrels in the next five years.

OPEC-member Iran earns more than $70 billion a year from its oil exports, bringing in 80 percent of its foreign currency revenue.

But experts say Iran still lacks enough money for investment, in large part because it spends so much on low-cost fuel for its own people, who pay about 42 cents a gallon at the government-subsidized rate.

At the same time, Iran grapples with a severe shortage of refinery capacity — meaning this oil-rich nation suffers the irony of having to import more than 50 percent of its gasoline. The government imposed a rationing system last year in hopes of trimming the amount it spends on subsidized fuel.

The Azadegan field — about 35 miles west of Ahvaz, a city near the Iraqi border — is a prime example of the challenges of going it alone under sanctions.

Iran estimates its holds reserves of about 33 billion barrels, making it one of the largest worldwide.

After years of negotiation, Japan's Inpex Company agreed in 2004 to invest 75 percent of a $2 billion plan to develop Azadegan. But two years later, Iran cut Inpex's share to 10 percent, complaining that the firm was delaying on the project — apparently under pressure by Washington.

Iranian officials say Russian and Indian companies have shown an interest in developing Azadegan since, but no deals have been signed.

Since September, Iranian firms have drilled six wells, all now producing, along with two facilities that separate oil and natural gas. The field has produced more than 25,000 barrels of crude a day since February.

Iran eventually hopes to bring production at Azadegan to more than 360,000 barrels a day — with some outside help if it can negotiate deals. For now, the goal is more modest: 65,000 barrels a day by next March.

The 400-member staff developing Azadegan bursts with pride.

"The implementation of this project shows we can do the same sort of activities as foreigners can do. It is no longer important if they don't come back here," said engineer Mohammad Reza Khaki, who led construction at Azadegan.