RE: Lincoln Field drilling14 Jan 2019 17:46
I was tickled pink to learn that the TO Leader's anchors and chains are to be pre-laid, which is a divergence from more normal procedure of carrying 'em onboard and then the anchor-laying taking place once the rig's in place.
For starters, pre-laying makes things considerably safer. (cf the capsize of the Bourbon Dolphin in 2007.) So that's a good thing. Plus it can be 'done at leisure', so to speak, working according to weather windows available, rather than battling against one particular tight one.
But the funny thing is, it more or less exactly corresponds with an idea I sent to Hurricane some 18 months ago, for discussion with the drilling contactors! Because it also reduces considerably some 'deadweight' carried aboard the rig, and correspondingly increases the amount of 'cargo' that can be carried once on location and operational. A thing known as 'variable deck load'.
The thing being, looking at the Leader's tech spec, she'd otherwise carry mooring lines and chains and lines good for at least 1500 m water depth (despite her DP capabilities), whereas Rona Ridge is one tenth of that. So a weight-gain of around 1000 tons could be made. Helpful also during rigmove, carrying the (weighty) anchors, as well: could be economic. Power-to-weight ratios apply, whether it's a racing-car or an oilrig.
My suggestion was that sometime in the future (I was thinking FFD) the rigs used on Rona only carried the amount required, rather than the whole nine yards. But someone's taken the idea a bit further, with the rig no longer carrying the mooring system at all, but having it pre-layed, and then hooking up when everything's in place and the weather's right. Which should be easy (everything's relative) and a heck of a sight less risky.
I'm absolutely not suggesting that my memo to Lower Easham nor conversations on the subject had any bearing on what's happening now, because the whole idea applies to any deepwater semi working anywhere in the (relatively shallow) N. Sea. But it's a step-change since we had the similarly-equipped TO Spitzbergen working for us. So I get this warm feeling that great minds have been thinking alike...