Jacket Construction for Heerema Vlissingen
by Ben Littler
Heerema Vlissingen have recently been busy with the construction of jackets for North Sea projects wind and oil & gas projects. They have recently completed fabrication of jackets for HelWin2 and Hejre, whilst construction of the large Gina Krog jacket in ongoing.
On 31 March the HelWin beta jacket was loaded onboard a barge for onwards transportation to the German section of the North Sea. The jacket is part of the HelWin beta HVDC platform, one of the main components of TenneT DC offshore grid connection HelWin2. The contract to construct the jacket was awarded by Siemens in 2012. Heerema Fabrication Group’s (HFG) in-house engineering team completed the design of the jacket before construction commenced in October last year.
Fast Work
Construction of the 4,500t 62 x 42.5 x 42m (outside dimensions at installation 64 x 42.5 x 48m) jacket took just 6 months. This equated to 175,000 man-hours of direct and indirect employment at HFG Engineering and Heerema Vlissingen, with no lost time incidents. The efficiency of the construction process, Heerema report, was the result of the optimisation of the fabrication process. Part of this was the construction of the jacket in two horizontal parts, which were then completed and loaded vertically. The offshore transportation and installation of the jacket is being performed by Heerema Marine Contractors’ Thialf platform.
In the meantime HFG’s fabrication facility Heerema Zwijndrecht, is working on the final construction phase of the 10,200t Helwin beta HVDC topside, due to be completed later this year.
Second Jacket
Following on from this, on 22 April, the 8,500t Dong Hejre launch jacket, with eight legs was skidded onto the Heerema barge at Vlissingen for Technip. The jacket measures 60 x 35 x 85m. The next step in this project is the sailing of the 900t pre-drilling wellhead deck, due to be loaded out in the first week of May. Installation will take place in the Danish section of the North Sea.
Gina Krog
Work continues on the largest jacket ever constructed at the Vlissingen site and will weigh 17,000t. It is being fabricated for Statoil Petroleum’s Gina Krog field development in the Norwegian sector of the North Sea. The jacket, on which construction commenced in December last year, is to stand approximately 142m tall, with a footprint of 50 x 60m and a top of 42.5 x 26.25m. Delivery of the jacket and its approximately 250t, 16 x 17 x 4m pre-drilling module, is scheduled for April 2015.
