Decommissioning and abandonment

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Decommissioning and abandonment

RECOVERY BY REEL BARGE

ƒ Reverse lay operation for un-concreted pipe ƒ Reassessment of weld stresses ƒ Loss of section – risk if rupture occurs on reel ƒ Already well established for small diameter lines and flexibles (Phillips in GoM in 2001)

Phillips recovered a line using reeling techniques. However, care needs to be taken with the stresses at welds, bearing in mind that the line may have already been yielded during the lay and now with thinner wall it will be further damaged. The tensioner has to work in reverse to keep tension on the reel and yet be able to lift the line up from the seabed. Ideally, it needs to be undertaken on lines that were initially laid from a reel barge. However, it may be possible to permit damage on recovery of lines that were laid by other methods, providing that they are not concrete coated. The consequence of breakage on the reel can be catastrophic. The welds in particular may be subject to fatigue fracture. The pipelines can then be brought ashore for disposal. This method has been used for a number of lines in the Gulf of Mexico and for one in the North Sea. (Amerada Hess-Dubious / Doubtful Flowline) Flexibles do not suffer from yielding on recovery and can be spooled up safely.

RECOVERYBYLAYBARGE