Iran had an estimated 137 billion barrels of proven oil reserves

Iran is the second largest producer in OPEC

Iran

As of January 2011, Iran had an estimated 137 billion barrels of proven oil reserves, 9.3 percent of the world's total reserves and over 12 percent of OPEC reserves. But, well, if one goes by the Iraqi oil minister, the country has 154.8 billion barrels of oil with new discovery of reserves in SouthWest Iran. And, the International Energy Agency has stated that the oil exports from the country stepped down to 1 million barrels a day in July from 1.74 million barrels a day in June.
Further, Iran is the second largest producer in OPEC, next only to Saudi Arabia. Crude exports contribute to about 80 percent of the foreign revenue. How profitable it'd have been for the country, then, to tone down its belligerence. Instead, Iran continues with its threat to block the Strait of Hormuz. This strait is a major oil route for countries in the Persian Gulf, including Iran. In 2011, about 17 million bbl/d flowed through. At its narrowest, the strait is just 21 miles wide. Iran uses this geographical formation to its advantage, threatening to choke the strait, at regular intervals. Sadly, Islamist fundamentalist threaten to take over 20% of the world's oil traffic if the West interferes with their nuke plans