Iranian production peaked at in 1974, but it has been unable to produce at that rate since the 1979 Iranian Revolution due to a combination of political unrest, war with Iraq, limited investment, US sanctions, and a high rate of natural decline. Iran's mature oil fields are in need of enhanced oil recovery (EOR) techniques such as gas injection to maintain production, which is declining at an annual rate of approximately 8% onshore and 10% offshore. With its current technology it is only able to recover about 25% of the oil in place, 10% less than the world average. Iran consumed of its own oil as of 2006. Domestic consumption is increasing due to a growing population and large government subsidies on gasoline, which reduces the amount of oil available for export and contributes to a large government budget deficit. Due to a lack of refinery capacity, Iran is the second biggest gasoline importer in the world after the United States. High oil prices in recent years have enabled Iran to amass nearly $60 billion in foreign exchange reserves, but have not helped solve economic problems such as high unemployment and inflation.
According to NIOC, Iran recoverable liquid hydrocarbon reserves at the end of 2006 was 138,4 billion barrels.
Apart from these considerable reserves, from the outset of oil industry in Iran in 1908 to the end of 2007, Iran produced some 61 billion barrels of oil.
Iran oil reserves at the beginning of 2001 was reported to be about 99 billion barrels, however in 2002 the result of NICO’s study showed huge reserves upgrade adding about 31,7 billion barrels of recoverable reserves to the Iranian oil reserves.
The 2002 NIOC reserve revision has came from following sources;
•Revision of oil-in-place volume which added 14,3 billion barrels of oil to Iran’s Oil in place reserves.
•Revision of the field’s recovery factors which increased average recovery factor of the revised oil fields from 29% to 36%.
•South Pars gas field Liquefied petroleum gas reserves (C3 and C4) about 3,2 billion recoverable barrels.
•New discoveries about 700 million recoverable barrels.
After 2003 Iran has made some significant discoveries which lead to addition of another 7.7 billion bbl of oil to the recoverable reserves of Iran.