Iran and Iraq are jockeying for top positions among the world's oil producing states.
Baghdad last week raised its estimated oil reserves 24 percent to 143 billion barrels, ranking third behind Saudi Arabia and Venezuela. Iran responded by overtaking its former adversary this week by raising its oil reserves to 150.3 billion barrels.
But energy analysts said oil reserves are just one factor in determining influence among the oil producing states.
"Actual production capacity is what counts when it comes to the Iraqi oil minister having muscle for negotiating with other OPEC ministers," Manouchehr Takin, senior analyst at the Center for Global Energy Studies, told the Financial Times. "The potential is there but converting potential to actual is complicated."
Iran produces 3.7 million barrels of oil per day compared with 2.5 million barrels per day in Iraq.
Members of the Organization of the Petroleum Exporting Countries at their Thursday meeting in Vienna are unlikely to adjust their output quotas as oil prices hover around $82 per barrel.
Iraq hasn't been subject to OPEC production quotas since the 1980s.