Tube-wave sensitivity to well integrity and leakage in legacy wells

Legacy wells are among the primary potential pathways for subsurface gas leakage, particularly in CO₂ storage projects. Ensuring integrity of plugged and abandoned wells is thus crucial for mitigating leakage risks, as compromised wells can allow CO₂ migration through damaged cement plugs or debonded casing-cement interfaces. Borehole seismic methods are uniquely suited for characterizing the near-well environment with relatively high resolution. In this study, we investigate the sensitivity of low-frequency Stoneley waves (so-called tube waves) in vertical seismic profiling (VSP) to well integrity issues and near-well CO₂ leakage using both field observations and qualitative validations with numerical modeling.