Here is the strike list:
LyondellBasell refinery in Houston.
Marathon Galveston Bay Refinery in Texas City.
Marathon Houston Green Cogeneration facility, Texas City.
Marathon Refinery, Catlettsburg, Ky.
Shell Deer Park Refinery, Deer Park.
Shell Deer Park Chemical Plant, Deer Park.
Tesoro Anacortes Refinery, Anacortes, Wash.
Tesoro Martinez Refinery, Martinez, Calif.
Tesoro Carson Refinery, Carson, Calif.
Another article:
Refinery strikes unlikely to move gasoline, oil prices
http://fuelfix.com/blog/2015/02/01/refinery-strikes-unlikely-to-move-gasoline-oil-prices/
Management and sales will run refineries on strike. Maybe not at full production, maybe at higher production.
The nearby, non union refineries should have capacity to make up any shortfall.