The U.S. Energy Information Administration (EIA) estimates that, excluding Iran, members of the Organization of the Petroleum Exporting Countries (OPEC) earned about $826 billion in net oil export revenues in 2013. This was a 7% decrease from 2012 earnings, but still the second-largest earnings totals during the 1975-2013 period for which EIA has tracked OPEC oil revenues. OPEC earnings declined largely for two reasons: a drop in OPEC oil production in 2013 (largely because of the supply disruption in Libya), and a 3% decline in average crude oil prices (as measured by the Brent crude oil price marker).

Saudi Arabia earned the largest share of these earnings, $274 billion in 2013, representing approximately one-third of total OPEC oil revenues. On a per capita basis, OPEC (excluding Iran) net oil export earnings reached about $2,520 in 2013. These net export earnings do not include Iran's revenues, because of the difficulties associated with estimating Iran's earnings, including the country's inability to receive payments and possible price discounts Iran offers its existing customers.

Based on projections from EIA's July 2014 Short-Term Energy Outlook (STEO), EIA estimates that OPEC (excluding Iran) could earn about $774 billion in net oil export revenues in 2014 and $723 billion in 2015 (unadjusted for inflation). These declines from the 2013 level are the result of projected declines in the call on OPEC crude oil production because of the large increases in non-OPEC production for 2014-15, as well as expected crude oil price declines that are also the result of declines in the call on OPEC crude oil production.
Source: EIA