Quantification techniques for potential CO 2 leakage from geological storage sites

CO 2 storage monitoring programmes aim to demonstrate the effectiveness of the project in controlling atmospheric CO 2 levels, by providing confidence in predictions of the long-term fate of stored CO 2 and identifying and measuring any potentially harmful leaks to the environment. In addition, the EU Emissions Trading Scheme (ETS) treats leakages of stored CO 2 from the geosphere in to the ocean or atmosphere as emissions, and as such they need to be accounted for. An escape of CO 2 from storage may be detected through losses from the reservoir, or migration through the overburden, into shallow groundwater systems, through topsoil and into the atmosphere, or through a seabed into the water column. Various monitoring techniques can be deployed to detect and in some cases quantify leakage in each of these compartments. This paper presents a portfolio of monitoring methods that are appropriate for CO 2 leakage quantification, with a view to minimising both uncertainties and costs. © 2011 Published by Elsevier Ltd.