3D UHRS Diffraction Imaging for Point Contact Detection in Offshore Wind Site Surveys

In 2024, a wind farm site survey was conducted in NW Europe using 3D Ultra High-Resolution Seismic (3D UHRS) acquisition, complemented by Sub-Bottom Profiler (SBP), multibeam echo sounder, side scan sonar, and magnetometer data. The goal was to improve the ground model and detect point contacts—mainly glacially transported boulders—that pose risks to wind turbine foundations. A diffraction imaging workflow was applied to isolate diffractions using a machine learning algorithm (U-net CNN). This allowed for the clear identification of sub-seafloor boulders that were otherwise hidden in conventional seismic stacks.

The study emphasized the advantages of combining 3D seismic with 2D SBP. While SBP offers higher resolution in shallow layers, it is limited in depth and prone to misinterpreting features due to sparse line spacing and polarity issues. In contrast, 3D UHRS can detect complex features like iceberg scour marks in true 3D context, helping to reduce false positives and improve geological interpretations. The results demonstrated that diffraction imaging within 3D UHRS offers a more reliable method for identifying buried hazards, supporting safer and more efficient wind farm design and construction