The CEMENTEGRITY project is a collaboration between 8 industrial and academic partners in 3 countries. The success of underground CO2-storage in depleted reservoirs or saline aquifers depends on the permanent residence of CO2 in the targeted reservoirs. Leakage can occur through the cement, or, more likely, along the contacts between the steel casing, the cement and the wall-rock; or through cracks and other pathways induced by, for example, thermal, chemical, or mechanical effects. At TU Delft we investigate how thermal cycling leads to leakage pathways through or along wellbore seals (e.g., cracks; micro-annuli), as well as the effects of subsequent flow through these pathways (i.e., self-enhancing vs. self-healing behaviour).