Improving subsurface investigations with acoustic impedance inversion: Concept and example from the German North Sea

Seismic inversion deduces the physical properties of the materials in the subsurface along two or three dimensional grids, a process which can significantly improve subsurface investigations in comparison to typically one dimensional geotechnical probing. Although methods such as impedance inversion are well established in the Oil and Gas industry, those methods are underused for near surface applications. There are very few case studies, which are however restricted to the very shallow subsurface due to the seabed multiple and previous published studies do not cover continental shelf settings as encountered in the North Sea. To invert challenging near surface data sets in this study, nonlinear optimization techniques with genetic algorithms for impedance inversion and one dimensional interval velocity estimation, established empirical relationships as well as a technique for low frequency trend addition are combined. The results of the highly optimized acquisition of an Ultra-High-Resolution seismic data set in the German North Sea, targeted processing including multiple removal and impedance inversion are presented. While the interpretability is already greatly enhanced in the impedance profile and uncertainty estimates can be directly derived, it will also be possible to develop regional soil mechanical models and to initialize shear wave inversion with these results.