This is a map of the US's energy flows, in 2002:
http://eed.llnl.gov/flow/02flow.phpNote that we import most of our oil. Be careful to read statements carefully. If someone claims "we get one-third of our domestic oil from the gulf," that doesn't mean we get one-third of all our oil from there. We do sell some oil abroad. Some of that might be for geographic reasons. Some of that has to do with the
type of oil. Don't make the mistake of thinking that oil is oil is oil. There are many different substances that come from the earth's innards that get called "crude oil." Some is heavy, some is light. Some is sweet, some is sour.
Katrina's effect on the energy markets is far from simple. This storm has done all of the following:
(1) It has temporarily closed some of the platforms in the gulf south of New Orleans.
(2) It has temporarily closed a major refinery near New Orleans.
(3) It has affected the flow of tankers into the Port of Southern Louisiana. Some tankers carry crude. Some carry distillates.
(4) It has temporarily closed the Henry Hub, which is
the major distribution point for natural gas in the US.
These are distinct events that have different but interacting effects.