This paper aims to highlight the basic differences between the site-specific assessment analysis (SSAA) of the jack-up units used in the offshore Oil and Gas (O&G) industry and the ship-shaped jack-up installation vessels used in the offshore wind industry. Whether used in O&G or in Offshore Wind Farms (OWFs), jack-ups typically require both geotechnical analysis of the seabed conditions and structural analysis of the elevated condition under various loading scenarios to ensure suitability for a given location. An SSAA is a generally acknowledged means of verifying that the jack-up can perform satisfactorily in the elevated condition at a particular site.
With developments in the offshore wind industry within the last decade or so, a modified version of the O&G industry approach to assessing the elevated condition may be used for OWF applications. For example, a comparative approach may be employed, where site parameters are compared to the design capability of the jack-up. The benefit of the comparative approach is that, other than foundation assessment, no further analysis is required. This approach may, however, be conservative for some locations. In the event of location-specific aspects being non-comparable, then an SSAA may be required for a particular location.
Although in principal similar, there are differences between the O&G and OWF approaches to site-specific assessment of jack-ups. The aim of this paper is to summarize the differences between these two applications of jack-up technology, particularly with respect to assessing elevated operations, and to increase the awareness of these differences among stakeholders in the fast-developing OWF sector.