Assessment of Imaging Approaches for Ultra-High Frequency Seismic Data in the Shallow Subsurface

Summary Ultra High Frequency-Multi Channel Seismic (UHF-MSC) data is increasingly being implemented in industry and academia to analyse and quantify shallow subsurface (c. <200m) conditions. However, its use is reliant on the production of consistent and reliable imaging or qualitative interpretations and the use of bespoke quantitative methodologies. The imaging of UHF-MCS data can be cast through the use of either post-stack, pre-stack, time-domain and depth-domain. Traditionally post-stack time migration has been preferred processing methodology due to its low computational costs and relative insensitivity to velocity errors. While pre-stack time migration improves on signal to noise ratios and produces higher fidelity images, it is pre-stack depth imaging (PSDM) which allows for the highest fidelity images, specifically where lateral velocity variations occur and the geology of the near-surface is complex. However, the increased imaging potential of pre-stack depth migration is countered by a greatly increase computational and user cost. Comparison of these migration strategies gives the opportunity to analyse the image improvements and the robustness of the velocity models used. The initial results show that the improvement in imaging and production of high-fidelity velocity models through the use of PSDM outweigh the increased computational and user cost during the UHF-MCS processing workflow.