Acergy France Sas

Florent Menet

Brice Viellard

Leire Ayestaran Basagoitia

A pipeline bundle for a riser tower or tie-back is manufactured offshore by suspending the bundle from an installation vessel, adding structural core sections successively to an upper end of the suspended bundle, lowering the bundle after adding each successive core section, and feeding one or more lengths of flowline pipe beside the core sections for incorporation into the bundle. The flowline pipe is coiled on a reel or carousel as a full-length piece before being uncoiled progressively as core sections are added to the lengthening bundle. The flowline pipe is then engaged with guide frames and/or buoyancy blocks supported by the core sections, by movement in a radially-inward direction through a radially-outer opening in a retainer formation. The opening is then closed to hold the flowline pipe in the retainer formation.

Fabrication of pipe bundles offshore

A pipeline including an accessory such as a flowline end termination or an in-line tee is lowered to the seabed and a mudmat foundation is subsequently lowered toward the seabed for subsea docking with the accessory to provide a permanent foundation support for the accessory. Once docked and with a mudmat of the foundation landed on the seabed, weight loads of the accessory structure and the attached pipe are transferred to the mudmat to provide a permanent foundation for the accessory structure. Before and during installation of the mudmat foundation, the pipe may be allowed to become embedded in the seabed. Temporary interim support such as buoyancy may be provided to the accessory to limit embedment into the seabed.

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Bezu St Eloi, France

Florent Menet