The effective spare capacity of 2.85 mbd is comprised of undesirable 2.50 mbd heavy sour crudes from Saudi Arabia and Kuwait, and only the remainder of 0.35 mbd is desirable light crude...

Is this new, having so much of the spare capacity in heavy and sour? What's the history?

Much of the surplus heavy sour crude capacity was used from 2003 to 2006. The OPEC production cuts in late 2006 and early 2007 were mainly heavy sour crudes from Kuwait and Saudi Arabia. http://www.eia.doe.gov/emeu/steo/pub/3atab.pdf

In 2002 there was significant surplus capacity of both heavy sour and light crudes.

Here is a chart showing surplus capacity history.


click to enlarge

http://www.eia.doe.gov/emeu/steo/pub/gifs/Fig10.gif