Seismic Inversion for Offshore Wind: Implications of Hard and Soft Soils on AVO Approximations

The application of amplitude versus offset (AVO) inversion to ultra-high resolution seismic (UHRS) data in offshore wind farm development is a promising method for improving the understanding of near-surface geology ( Karkov et al., 2022 ). The elastic properties calculated through AVO inversion can improve the ability to differentiate between soils and potentially reduce reliance on CPTs when planning location, foundation design and identifying hazards. In this study, we present the results of synthetic tests comparing Aki-Richards (1980) approximations to exact Zoeppritz (1919) equations using true velocity changes observed in logs acquired in the Danish North Sea, a modelled response for glauconite sand within a sand background and an interbedded cemented and uncemented carbonate. In both AVO reflectivity modelling and seismic wedge modelling, we clearly observe significant differences in response beginning as early as 20 degrees and becoming more significant with larger incidence angles. This suggests that AVO inversion of UHRS data for offshore wind farms may improve with the use of higher order physics to accurately predict elastic properties and/or synthetic CPTs.