L6B umbilical installation

The L6B platform is a remote tieback to L8P4 in the L blocks in the Dutch section of the North Sea, approx. 30 km northwest of Den Helder. It is the newest addition to the Wintershall offshore assets in the Dutch section.

Facts and figures

Year of Construction
Project categories

Work was divided between the loading in Newcastle, L8P4 platform and the newest site of L6b, at a depth of 29 metres. VBMS developed the engineering procedures and performed the work to load the 19.5 km umbilical, perform J-tube pulls directly from the installation vessel Ndurance, lay the entire umbilical en route and complete the second end direct J-tube pull-in onto platforms without having to interrupt the work or temporarily lay down the umbilical. Installation and J-tube pull-ins were performed from the dedicated installation vessel Ndurance. The umbilical was then laid subsea, until the second end at L6B, where it was over boarded and pulled in via the quadrant system in a controlled manner. Finally, VBMS performed post-installation jet trenching and a follow-up as-laid survey of the umbilical route and verified burial of the umbilical.

Scope of work

  • Umbilical load-out at DUCO Newcastle (UK) onto the installation vessel Ndurance.
  • Platform preparation on L8-P4 and L6-B.
  • Umbilical length calculation for installation of the Trelleborg seal unit and bend restrictors.
  • First end pull-in of the umbilical at platform L8-P4 including hang-off of umbilical end.
  • Conventional laying, including crossing the 36-inch live gas pipeline Callantsoog.
  • Second end pull-in at platform L6-B with quadrant method, including hang-off of umbilical end.
  • Umbilical burial by trenching with assistance of the Topaz Commander.

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