Iran is one of the most hydrocarbon-rich areas in the world. Since the nation's first oil well in 1908, 145 hydrocarbon fields and 297 oil and gas reservoirs have been discovered in Iran, with many fields having multiple pay zones. A total of 102 fields are oil and the remaining 43 are gas, and there are 205 oil reservoirs and 92 natural gas reservoirs. According to Iran Energy Balance Sheet (2009, in Persian), 78 of these fields are currently active, with 62 onshore and 16 offshore, leaving 67 fields inactive at present. Some 23 hydrocarbon fields lie in border areas and are shared between Iran and adjacent countries, including Kuwait, Iraq, Qatar, Bahrain, UAE, Saudi Arabia and Turkmenistan.
The Permo-Triassic successions (the Dehram group in Iran and its lateral equivalent, the Khuff formation), are major gas-producing intervals in these basins. The supergiant North Dome/South Pars field alone is estimated to hold about 19% of the world’s total gas reserves, producing gas and condensate from these intervals.
Iran still has huge potential for new significant gas discoveries: areas such as Caspian Sea, North East, Central Kavir and especially areas starting from Aghar and Dalan gas fields in Fars province up to the Strait of Hormuz and Central Persian Gulf have considerable potential for undiscovered gas. According to Exploration Directorate of NIOC, there are about 150 unexplored anticlines in Iran.
In 1998, the US Geological Survey estimated Iran's undiscovered gas resources to be in the range of 226 to 820 trillion cubic feet, with a probability-weighted average of 465 trillion cubic feet (13.2 trillion cubic metres)
In January 2008, Iranian Minister of Petroleum Gholam-Hossein Nozari said, "NIOC has a target of producing one billion cubic meters of gas per day.
Iran's ten biggest non-associated gas fields: