Green Volt — 3D UHRS quantitative interpretation

SolidGround supports the Green Volt floating wind project — set to become the world’s largest commercial-scale floating offshore wind farm, developed by Flotation Energy and Vårgrønn. Our contribution focuses on quantitative interpretation of the UHRS dataset, using UHR3D pre-stack inversion to derive reliable elastic and geotechnical property volumes that feed directly into ground modelling and geotechnical understanding to support the project’s FEED activities.

The scale and quality of the seismic survey — delivered by TGS, with survey management and QC provided by Global Maritime — represent a significant step forward for geophysical site characterisation in offshore wind. From the 3DUHRS pre-stack data, SolidGround extracts quantitative soil and rock parameters constrained and validated against borehole, CPT, SCPT, and laboratory test data, building a high-resolution geotechnical model of the site.

Seismic-derived CPT parameters — cone resistance (qc), sleeve friction (fs), porewater pressure (u2) and soil behaviour type index (Ic) — are predicted spatially across the site using a probabilistic, kernel-density framework calibrated to the measured CPTs. Elastic outputs (acoustic and S-impedance, VP, VS, VP/VS, density, bulk and shear moduli) feed preliminary foundation and anchor design assessments. Per-soil-unit residual statistics (standard deviation, P5/P16/P50/P84/P95), derived via leave-one-out cross-validation against the geotechnical calibration data and reported following DNV-RP-C207, quantify the uncertainty in both the elastic and CPT outputs.

The resulting coherent dataset informs geotechnical field-campaign planning, reduces investigation redundancy, and enables efficient and reliable design and installation of foundations and anchors for the floating array.