February 28, 2014

This development area extends over approximately 8660 square km and is therefore the largest site zoned in the UK to date, with a target capacity of at least 7.2 GW of electricity.

Project Title

Dogger Bank Metmast Installations

Location

Dogger Bank, UK Sector of the North Sea

Country

United Kingdom

Client

Fred. Olsen Wind Carrier

Business Sectors

Offshore Wind Energy

Services (Technical Disciplines)

Geotechnical; Offshore Engineering; Soil-structure interaction

Project Objectives

Dogger Bank is an offshore wind farm site located in the UK sector of the North Sea between 125 and 290 kilometres off the east coast of Yorkshire. This development area extends over approximately 8660 square km and is therefore the largest site zoned in the UK to date, with a target capacity of at least 7.2 GW of electricity. The water depths range from 18 to 63 metres, with the potential for approximately 4GW development capacity in less than 30m water depths. To facilitate the development of this site, two meterological measuring masts (metmasts) were installed offshore in late 2013 using the Brave Tern installation vessel, which was newly commissioned by Fred. Olsen Wind Carrier in 2013 and sailed out to Dogger Bank on its maiden project. The first offshore operation was to install two suction bucket foundations to support the metmasts.

Our Role

The 132m long Brave Tern jack-up vessel has an 800 tonne crane capacity and requires a stable operating platform by using 14m wide spudcan feet that penetrate into the seabed. GDG were tasked with assessing the site specific suitability for the new vessel to ensure safe and efficient jacking operations. By using state of the art soil mechanics and foundation engineering principals, GDG completed a leg penetration and extraction analysis for the spudcan feet and determined the site specific response anticipated at the Dogger Bank locations. The risk of different soil failure modes were assessed and where necessary GDG provided mitigation solutions to ensure safe jacking operations. The project was successfully completed with the actual offshore behavior comparing well to the GDG predictions.

Since completing this project, GDG have further developed in-house jack-up software that includes large strain numerical analysis procedures for estimating 3-dimensional spudcan behavior in varying ground conditions.

Geoscience Ireland Contact

Paul Doherty: pdoherty@gdgeo.com