Let's say that below-sea, naval and air threats against a offshore drilling rig were eliminated, could Germans be able to produce one? When were the first real offshore drilling rigs produced?
It would have to be the North Sea (I think - unless there are rigs in the Baltic?). This woud obviously clash with us English... I do doubt that the ability to poduce & impliment a proper deep-sea oil-drilling rig would be something anybody possessed back them. I *think* that sea platforms did not really start up until the 1960s/70s
Offshore oil rigs When did offshore drilling start in the Caspian sea and Gulf of Mexico - not much use to Germany but was the technology there?
The drilling in the Gulf of Mexico were not around until after WW2. At least the ones on the central Gulf Coast, that is.
If Germany had had the technology to build ships large enough to transport oil from rigs to ports in a cost-effective manner they would have used that technology for their navy rather than for such costly and risky programs. Obviously the only underwater oil reservoirs available to Germany would be those under the North Sea, and those are closer to Britain than could be survivable for the German crew of the rig.