Another issue with building a refinery, is the support systems that have developed around the refineries along the gulf coast.
Lets use shell and tube heat exchangers as an example. Heat exchangers are used by refineries to regulate the temps of the chemicals used to refine oil and chemicals.
In 1990 Citgo in Lake Charles had a heat exchanger in a gasoline unit that started leaking. The unit was shutdown, the exchanger puled out and sent to where I was working for repairs.
Every hour the unit was down, citgo was losing $100,000. That was back when gas was $1 - $1.25 a gallon. In todays money, it would probably be closer to $500,000 an hour. We got the job because the company I worked for was just down the road from citgo. Could you imagine having to ship a part 200, 300 or 400 miles, while that unit being down cost $500,000 an hour?
Refineries have to have a support chain nearby - equipment rentals, pipe shops, machine shops, heat exchanger shops, general welding / fabrication shops, welding supply shops for welding rods, safety equipment, cutting torches,,, and the list goes on and on.
Sure you could build a refinery in about a decade, but what are you going to do when the cooling towers start leaking? Where are you going to rent the cranes from to pull the old parts out of the tower? You need a flange machined to stop it from leaking, where is the nearest machine shop with a portable machine unit?
Then there is the sheer weight and size of some of the parts used in the refineries. Some of those towers have to brought in by ship, then things that look like tank tracks used to transport the part from the port to the refinery. We are talking about parts that weigh hundreds of tons.