Repurposing UHR Seismic Boulder Detection Technology for Offshore Windfarms to Locate Decommissioned Wells for CCS Applications

Summary This study explores the repurposing of a dedicated ultra-high resolution seismic (UHRS) diffraction imaging, originally developed for boulder detection in offshore windfarm projects, for locating decommissioned wells in carbon capture and storage (CCS) applications. Using a 3D acoustic finite-difference model, the research simulates the seismic response of a cement plug within a fluid-filled well embedded in marine sediments. The model includes both a cemented well and a control boulder to evaluate detection capabilities. The diffraction-based method utilizes a dedicated hydrophone array, beamforming and synthetic aperture to isolate and enhance diffracted energy. Results demonstrate that diffraction anomalies associated with the cement plug’s top and bottom boundaries align precisely with the known plug positions,confirmed by the near-perfect match of the first zero-crossings. These results showcase the accuracy, resolution, and swath imaging potential of UHRS diffraction imaging for detecting small-scale subsurface features. This approach could offer a promising tool for offshore CCS site screening, especially in scenarios where well locations are undocumented or ambiguous.