ZUG, Switzerland -- Saipem’s Castoro Sei (C6) pipelay vessel has reached German waters off the island of Rügen in the Baltic Sea, where it will continue laying the Nord Stream gas pipeline.
Castoro Dieci (C10), a smaller vessel designed to lay pipes in shallow waters, has so far laid 27 km (16.8 mi) of the pipeline in the Bay of Greifswald. The C6 will recover this pipeline string and continue laying the pipeline towards Bornholm, Denmark.
The laying-sequence means that the pipeline must be laid down and picked up again at several locations, under an operation called “Abandonment and Recovery” (A&R).
According to Dr Georg Nowack, Nord Stream project manager for Germany, construction of the German section is almost four weeks ahead of schedule. On Sept. 19, the C10 had sealed the pipeline with an A&R-head and lowered it to the seabed. The C6 has since been retrieving the pipeline back into the vessel’s main production line. The A&R-head will then be removed, with further pipe segments welded to the pipeline string.
The 150-m (492-ft) long C6, which started work in Swedish waters in April, can lay up to 2.5 km/d (1.55 mi) of the pipeline. It should have completed the remaining 55 km (34 mi) of the 82-km (51-mi) section in German waters later this month.
C10 is laying the second parallel string of the pipeline, and will finish its program after abandoning the second string east of Rügen. C6 will pick up this string next September and continue laying the second line.
When both strings are completed in 2012, each will be 1,224 km (760 mi) long. Once onstream, Nord Stream will transport 55 bcm/y (1.9 tcf/y) of gas to markets throughout Europe.