I don't believe this or some of your other facts. Got a source for this, or did you just make it up?
Care to list the 8 refineries you are counting? I looked at this PDF list and couldn't come up with that many: http://www.epa.gov/ttn/chief/le/benzene/benz_apb.pdf
I count Belle Chasse and Chalmette in New Orleans, one in Mobile, and one in Pascagoula.
There are about 148 or 149 refineries in the country.
http://www.eia.doe.gov/emeu/cabs/usa.html
As far as 'imports and exports will cease' - there just isn't any truth to that. The river isn't blocked. Cargo will be re-routed around New Orleans. Jacksonville, Savannah, Houston and smaller ports will pick up the slack. Transport costs will increase slightly. CSX and NS should do quite well. CN, KSC, BNSF and SP should also benefit.