Here's OPEC's biggest problem

AP/Karim Kadim

• OPEC used to have a lot of spare capacity for oil reserves.
• It has lost the ability to keep that capacity up, for a number of reasons.
• This affects oil prices, and can cause unpredictability in the market. 
• For now, the oil market is set to tighten.

OPEC’s spare capacity is not what it once was, a development that opens up a larger upside risk to oil prices.

A constant feature of the oil market is the prospect of unforeseen supply outages...