The International Energy Agency in Paris estimated in December the sustainable production capacity for the Organization of Petroleum Exporting Countries at 35.4 million b/d, with actual output at 29.05 million b/d, leaving a spare capacity of 6.35 million b/d. That spare capacity drops to 5.37 million b/d if less dependable producers such as Iraq, Nigeria, and Venezuela are eliminated.The US Energy Information Administration put OPEC's spare production capacity in December at 5.03 million b/d, zeroing out Algeria, Ecuador, Iraq, Nigeria, and Venezuela. It estimates OPEC's maximum production capacity at 34 million b/d.Using both the IEA and EIA numbers, Adam Sieminski at Deutsche Bank, Was...