I just paid a visit to the oil rigs near the Texan coast south of Houston … well …
I would also add helipads on ships as well - think I found some on skyscrapers that could be landed on.
I guess no one cares … so fat chance of that happening. Well … maybe with the official implementation of helicopters.
as of USA WU10 - still no collision on the default oil rigs…
I had to add helidecks with collision when doing oil rig placements for AK and SBA ( and just finished doing 75 oil rigs in the Adriatic Sea )
Oil Rigs updated with landable helipad ( CA & AK ) - Third Party Addon Discussion / Airports - Microsoft Flight Simulator Forums
They really should update the oil rig asset for November - it really needs collision and better detail around the helideck, with pad lighting, windsocks, etc. Better yet - add a variety of oil rig models.
The official trailer showed a helicopter flying near an oil rig landing pad. I have to assume they will fix this by November, but it will not surprise me if they don’t.
yeah, “near.”.. 
although I checked the US Bank bldg in LA, and the PG did have decent collision, so all of the rooftops in LA are landable.