I’m sure readers recall the grounding, refloating and salvage of the cruise liner Costa Concordia a few years ago. It was one of the most complex and difficult marine salvage jobs in history, and success was far from a foregone conclusion.
Whilst the ship is no more, the technologies developed and used to salvage her wreck are now being applied in a new and innovative way.
It is one of several companies trying new ideas to win business in the market for dismantling disused oil platforms.
In Britain’s ageing oil fields alone, the opportunities could be worth up to 17 billion pounds ($21.85 billion) before 2025, according to industry body Oil and Gas UK. The ideas could then be deployed to other maturing fields such as in the Gulf of Mexico and southeast Asia.
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Oil platforms are usually removed piece by piece and taken to the shore using complex vessels. The floating tanks that Ardent used to lift the Costa Concordia, are much cheaper to use, industry experts say.
There’s more at the link.
It’s an interesting approach, very different from the more complex techniques used up until now. Here, for example, is the removal of a 14,000 ton rig from the North Sea by lifting it with a ship after cutting its legs.
Caissons (a.k.a. tanks or sponsons) are nothing new, of course: they’ve been used for centuries to assist with underwater construction in building bridges and digging tunnels, and also in more recent years to refloat grounded vessels. However, to use them to float a big oil rig off its base, or lift the base off the ocean floor and then tow it to shallower water, is new. I presume they’d be attached to the legs, which would then have to be cut off quite deep beneath the water. One wonders whether caissons can provide adequate stability to such a tall object, as well as buoyancy.
It’s going to be interesting to watch this, and find out if it can be made to work.