This comes from the report 'Deep geological storage of CO₂ offshore UK: containment certainty' from the Department for Business, Energy and Industrial Strategy (BEIS). We urge you to take a look at the full publication, along with its supporting document.
The full publication can be found here: https://www.gov.uk/government/publications/deep-geological-storage-of-carbon-dioxide-co2-offshore-uk-containment-certainty