To main content

Transport and installation turbine foundations offshore wind farm, Wikinger

<div>The Wikinger offshore wind farm has been developed by Iberdrola in the Baltic Sea area, within the German Exclusive Economic Zone (EEZ). The offshore site is about 34 km northeast of the island of Rügen, and covers an area of roughly 50 km², within which 70 wind turbine generators (WTG) of 5 MW and one offshore substation (OSS) are being installed. The water depths for installation range between 36 and 42 meters. When completed the windfarm will deliver 350 MW electrical power to the German national grid. The transport and installation of the 70 WTG foundations and the piles for the OSS has been carried out by Boskalis.</div>

Foundations

Each of the WTG foundations consists of a four legged jacket including a transition piece and four piles. Lengths and weights vary due to different water depths and soil conditions. The piles are driven into the soil prior to jacket installation (pre-piled foundation concept). Furthermore the piles are dredged and cleaned internally prior to jacket installation. After installation of the jacket the connection between the jacket and the piles has been realized by grouting.

Transport

A significant part of the Boskalis scope comprises the safe transportation of the piles and jackets from their fabrication sites in Seville, Aviles and Fene-Ferrol, Spain, and from Lindø and Aalborg, Denmark to the Iberdrola feeder port in Sassnitz, Germany. A variety of assets has been deployed for the transportation. Piles are transported using tugs and barges for the transports from Aalborg and geared vessels from Seville and Aviles. Jackets from Lindø are also transported by tugs and barges. The transport from Fene-Ferrol via the Bay of Biscay and the North Sea to the Baltic Sea has been done by Dockwise S-class vessels (Swan and Tern) on 7 consecutive voyages transporting 4 jackets each voyage.

Installation

Installation of the jacket foundations comprises four consecutive steps. The piles are driven into the seabed using a specially designed self levelling pre-piling template able to position the piles to the exact tolerances. The piles are driven by a 1200 kJ hydro-hammer. The template and hammer spread are deployed from the Giant 7 converted for the Wikinger Project into an offshore crane barge by installing a 1000 t Liebherr crane. Once installed the piles are dredged and cleaned using specialist tools deployed from two DP vessels. Jackets are installed with one of the Boskalis sheerlegs Taklift 4 with a capacity of 1400 t. After installation the annulus between the jacket legs and the piles has been grouted using high strength grout pumped from a grout factory deployed from another DP vessel. After grouting the jacket foundation has been inspected and handed over to the client.

Tailor made vessel and specialist tools

A wide range of self-owned vessels have been deployed on the Wikinger project ranging from support vessels, multicats, tugs, barges, a rock dumping vessel, installation vessels and one of our sheerlegs. In addition various support vessels, tugs and barges were hired on the project. In total some 25 vessels were deployed.

Noise mitigation

Noise mitigation measures are in place during pile driving to meet the strict requirements set by the German Authorities for pile driving in the Baltic Sea. Three noise mitigation measures have been applied:

  • Double big bubble curtain on the sea bottom around the template and the installation vessel (Giant 7)
  • Small bubble curtain around each of the four cages of the pre-piling template
  • Hydro sound damper deployed around the pile (contingency in case the criteria are not met)

All installation activities have been executed well within the noise limits ISO requirements.

Conclusion

Boskalis has proven its capability to execute complex projects to the highest safety and environmental standards overcoming difficult technological challenges using tailor made vessels and equipment.

Related projects

Selected filters
Taklift_4.jpg

Jotun A

The Jotun A FPSO, a 92,000 DWT FPSO capable of producing 70,000 bpd, began producing in 1999 on the Jotun field (Norway). As part of Vår Energi’s investment in increased oil recovery from the Balder field in the North Sea an upgrade of the Jotun FPSO is required. The Balder Future project will extend the life of the field (PL 001) by 2045, giving Norway’s oldest license a lifetime of 80 years.

Bokalift_1.jpg

L10 -C -D & -G Decommissioning

Neptune Energy Netherlands B.V. (Neptune) has awarded Boskalis the contract for the removal, transport and load-in of three platforms. These platforms are located in the Dutch North Sea,
approximately 90 km west of Terschelling.

Large-190412_-_38.jpg

Borssele ALPHA/BETA

Royal Boskalis Westminster is a leading global marine contractor and services provider. With safety as our core value, we offer a wide variety of specialist activities to the oil & gas and renewa-bles sectors. These activities include marine instal-lation and decommissioning, seabed intervention, marine transport and services, subsea services and marine survey. In addition, Boskalis is a global dredging contractor, provides towage and terminal services across the globe and delivers marine salvage solutions. By understanding what drives our clients we are able to provide the solutions that enable them to meet their specific business goals. For this reason we are constantly looking for new ways to broaden and optimize our offering and are committed to expanding our proposition, supported by our financial strength. With our committed professionals in engineering, project management and operations, 800 special-ized vessels and an unprecedented breadth of activities in 90 countries across six continents we help our clients in the offshore industry push boundaries and create new horizons.

E_-_Tower_Crane_Installation.JPG

Çanakkale 1915 bridge

The 1915 Çanakkale Bridge, also known as the Çanakkale Strait Bridge, is a proposed suspension bridge being constructed in the Çanakkale area in Turkey. Situated just south of the towns of Lapseki in Asia and Sütlüce Village in Europe. The bridge will span the Dardanelles strait, about 10 km south of the Sea of Marmara.

Aberdeen bay offshore windfarm project

Boskalis was responsible for the eleven suction bucket jacket foundations, scour protection, 66 kV inter array and export cables and the installation of the wind turbine generators.

NASR.jpg

NASR full field development

Boskalis was subcontracted to install 2 topsides and 3 jackets in the NASR and Umm Shait oil fields: The Accommodation Platform/AP Jacket, the Separation Platform/SP Jacket and the Gas Treatment Platform/GTP Jacket are installed in the NASR Field. The installed net weights of the jackets ranged from 2,270 to 3,070 metric tons.