I know the oil rig in fo2 got blown to peaces but there must still be a few out there that never got hit? I mean there is no way America only had one oil rig going at one time right? I am not talking about the enclave this is just a general question.

Theres probably a couple left. The chances of seeing another one is probably slim.

Are we talking about Oil Rigs as Shelters, or just plain oil rigs.

Plain oil rigs - With the exception of the one remaining deposit in the pacific, there was no more oil for oil rigs to get. There may be some abanonded on the high seas if it were uneconomic to bring them in for scrap, the others recycled. I doubt if any are in any sort of "Seaworthy" condition if they survive.

If we're talking oil rigs as shelters, the "Enclave Facility" we believe to be unique.

Pretty sure that was the last and ONLY one at the time (almost certainly in the USA and probably the entire world).

The reason it was so well fortified was that it was over the last accessible oil field.

In terms of remaining Enclave bases, Chicago is the only place that could possibly still have an Enclave garrison.

In terms of Oil Rigs: I'm sure there are many abandoned Oil Rigs out there in the world's oceans.