Full-waveform inversion of cross-hole GPR data collected in a strongly heterogeneous chalk reservoir analogue with sharp permittivity and conductivity contrasts

Chalk sediments form an important reservoir for groundwater onshore and for hydrocarbons in the Danish sector of the North Sea. Cross-hole Ground-penetrating radar (GPR) tomography is an efficient method to investigate subtle porosity variations in the chalk. Traditional ray-based inversion techniques provide models that are overly smooth and have relatively low resolution. We present preliminary results from full-waveform inversion of data collected in strongly heterogeneous chalk. The resolution of the tomograms has improved significantly compared to models obtained from travel-time tomography. The new models also reflect the variability seen in 1D drill core analysis. The results indicate that fullwaveform inversion is a well-suited inversion technique for high-resolution time-lapse-based flow characterization.