Risk assessment of CO2 leakage through the caprock

The primary focus of this study was to evaluate the impact of CO2 leakage from the storage zone through potential leakage pathways and leakage impact factors (risks). During site selection and assessment of potential CO2 leakage there will be a high number of uncertainties within the data. The aim of this risk assessment process is to reduce this uncertainty by utilising expert elicitation to identifying the global CO2 leakage pathways and leakage impact factors (the risks), comprehend the contribution and impact each risk could make to CO2 leakage through the caprock and evaluate the risks based upon whether each potential leakage pathway or leakage impact factor presented a significant CO2 leakage risk if it were not properly quantified. This provides a site characterisation tool focussed on caprock leakage risk based on a ranked procedure for data collection where the highest data quality must be associated with the highest leakage risks. A similar methodology could be used for the other components of the storage complex including reservoir capacity, injection, monitoring etc.