"An engineer's wet dream"

That's how a Norwegian engineer described the Aasta Hansteen spar rig, which is being assembled off Norway.  It's a phenomenally complex piece of construction, in two very large pieces. It was mostly manufactured and assembled in South Korea, with parts coming from all over the world, including Norway. Once built, it was shipped in two parts to Norway, where it's being put together.

Here's a video of the construction of the spar, the part that will float largely submerged and support the superstructure.

Here's the spar being "sunk" off the Norwegian coast, putting it into a vertical orientation to receive the superstructure. It's just like a giant submarine, with ballast tanks to adjust its depth and orientation.

And here's the superstructure being mounted.  It was shipped to Norway aboard a single vessel, then moved onto the two submersible ships you can see at either side. They took it out to the spar and positioned themselves on either side of it, then the superstructure was mated to its supports.

The gas field isn't yet operational - that's scheduled for late 2018.  I have no idea how much money has been spent on preparing this field, and buying and installing all the equipment, but it's got to run into the billions!  Very impressive.

Peter