Most of the refining is sheltered behind Galveston Island and the Bolivar Penninsula, or farther south inside of Corpus Christi Bay, which also sheltered by barrier islands. However, depending on the exact track, a hit on Galveston could be much worse on the oil production side of things.
That's a really good graphic.
That is incorrect. Barrier islands don't shield a damn thing. They're deathtraps which disappear during the storm surge.
The storm surge will go over them or around them and get to the refineries without missing a blink.