<p dir="ltr">This data relates to numerical analyses of CO₂ injection well integrity, focusing on degradation of cement sheath bonds with the casing and caprock. The cement sheath and caprock are modelled as thermo-poroelastic materials subject to coupled thermal, hydraulic, and mechanical (THM) behaviour. Debonding at cement-casing and cement-formation interfaces is explicitly modelled in the finite element formulation using a cohesive zone model. </p><p dir="ltr">The presented data includes predictions of the THM behaviour of the well system alongside the timeframe of damage development and the apertures of any resulting microannuli for a selection of cases presented in the linked publication (please contact the corresponding author for further information).</p><p dir="ltr">These findings contribute to robust CO₂ storage risk assessments and support planning of corrective measures to ensure long-term wellbore integrity during geological CO₂ storage.</p>