| A wide range of tools and methods are potentially useful for monitoring CO2 storage sites.
Geophysical, geochemical, well-based, surface-based and even airborne and satellite
monitoring systems have been successfully demonstrated at a number of CO2 injection sites.
The challenge for industrial-scale storage is to select which tool combinations together
provide a cost-effective and technically robust site monitoring system. The key
element of an integrated monitoring system is likely to be deep-focussed, aiming to
demonstrate that processes in the storage reservoir are proceeding as predicted and to give
early warning of encroachment of the CO2 plume into areas of containment risk.
Shallow–focussed systems, possibly concentred around identified containment risks (such as
old wells), aim to aim to demonstrate ultimate site integrity and satisfactory emissions
performance. In the event that leakage to surface did occur, shallow monitoring
would be required to identify potentially hazardous buildups of gas and enable
suitable remediation to be undertaken. Suitable monitoring systems are highly site
dependent, but key deep-focussed methods are likely to include surface 3D time-lapse
seismic and downhole pressure/temperature monitoring. In their different ways, these
tools are integrative, providing diagnostic responses from the 3D volume of the
storage system. Key shallow-focussed methods may include shallow geochemical
sampling, complemented by atmospheric measurements and possibly remote sensing. |