3D Ground Model Insights for Offshore Windfarm Development

High resolution (HR) towed streamer 3D seismic for oil and gas exploration is capable of efficiently yielding high-resolution near-surface imaging. Yet, much higher frequency shallow images are often sought by windfarm developers. After comparing the features of HR seismic, ultra-high resolution (UHR) seismic, and UHR acoustic profiling, I summarize the traditional approach when building windfarm ground models. Most workflows acquire a reconnaissance 2D grid of seismic / acoustic data, which is then crudely interpolated to build a reference 3D model, and then various geotechnical data are propagated into that 3D model. Bathymetric data are typically available as a 3D horizon for the seafloor and associated hazards, but the spatial uncertainty in soil properties and stability rapidly increases with increasing depth below the seafloor. UHR 3D towed streamer seismic can provide remarkably accurate 3D subsurface insights with feature detection <0.5m, and both new acquisition of HR 3D multisensor seismic data and bespoke reprocessing of 3D multisensor seismic data can achieve near-surface image resolution of about 2-3m. I consider different strategies to combine the merits of both HR and UHR 3D towed streamer seismic when building regional ground models in an efficient manner and integrate contemporary views on the role of geosciences throughout the windfarm lifecycle.