I wouldn't worry about the extraction platforms. Refineries, maybe, but they're all equipped with on-site backups and the technology is pretty much mechanical, except for some electronic components that are non-essential.
Diesel engines and most electronics on ships will also be unaffected, since the ships are grounded by water and those engines are pretty much mechanical monsters - the supply of fuel will most likely go uninterrupted (heck, I'd worry more about governments and criminals using the opportunity to start something)...
There is nothing that exists in Isolation today. Everything thing depends on each other. That's the most beautiful and the scariest part.
When these sort of scenarios are discussed, we take into account only the first impacted entity. We don't analyze the things that get impacted because of the first entity and things that depend on each other. There are going to chained failures of systems. Each depending on other to recover. While none can at the moment.
When you see the whole equation in the entirety you will realize a single massive failure in one entity can send you back centuries.
Refineries, maybe, but they're all equipped with on-site backups and the technology is pretty much mechanical, except for some electronic components that are non-essential.
Most of a modern refinery is controlled by PLCs and computers.
Diesel engines and most electronics on ships will also be unaffected, since the ships are grounded by water and those engines are pretty much mechanical monsters - the supply of fuel will most likely go uninterrupted (heck, I'd worry more about governments and criminals using the opportunity to start something)...