Energy transition

Shear-Wave Velocity Data Assists Modeling for Offshore Windfarm Development

The goal of the project described in this paper was to test the added value of shear-wave velocity interpreted from underwater multichannel analysis surface waves, particularly as a propagation tool of geotechnical information.

(a) Back deck of the surface vessel showing the UMASW spread before deployment; (b) acquisition principles of the UMASW spread.
Fig. 1—(a) Back deck of the surface vessel showing the UMASW spread before deployment; (b) acquisition principles of the UMASW spread.
Source: OTC 35354.

In the course of a research and development (R&D) project dedicated to quantitative ground modeling, underwater multichannel analysis surface-wave (UMASW) data were acquired within an offshore windfarm area currently in development in the North Sea. The goal of the project described in the complete paper was to test the added value of the shear wave velocity (Vs) interpreted from the UMASW, particularly as a propagation tool of geotechnical information. While UMASW, together with seismic refraction, is regularly used to characterize the ground for burial or trenching purposes, it appears also to bring valuable design parameters for offshore wind turbine foundations.

Introduction

To investigate the value of Vs in the performance of quantitative ground modeling studies, an internal R&D initiative was launched aimed at acquiring Vs data and the associated uncertainties of foundation depth of an offshore windfarm currently in development. These data will be tested at a later stage for the propagation of geotechnical parameters used in foundation design.

The acquisition consisted of obtaining Vs data through UMASW methodologies around two distinct geotechnical boreholes and along a corridor tying the two areas.

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