Quantification Techniques for CO₂ Leakage

Publication Overview

On the whole, the primary focus of CO₂ storage monitoring techniques has been to monitor plume behaviour in storage formations, and to detect leakage to the biosphere. However, for emissions trading under the EU ETS and for national GHG inventory purposes it is necessary to quantify leaked emissions to the atmosphere should leakage occur, and there is a low level of understanding of the capabilities, accuracies and uncertainties of measurement techniques for this application.

Publication Summary

Due to the nature of a CO₂ geological storage site, techniques to detect any potential leakage or likely pathway will be necessary prior to deployment of direct or indirect instrumentation for quantification. Deep subsurface methods will therefore be important to identify any potential leakage before it reaches the near subsurface, atmosphere or water column. Baseline monitoring is needed before any compartment is altered by the effect of CO₂ injection or exposure, especially as large spatial and temporal variation of background levels is likely to contribute the largest level of uncertainty. Modelling is also key to the planning of monitoring programmes; hence methods to help constrain model parameters and reduce 2 uncertainties will add value. Preference should be given to methods that are concurrently employed for performance monitoring, are favourable in terms of cost and benefit, are most reliable and accurate, can be deployed in conjunction with other techniques, can be operated with minimum human effort, are robust and have added benefit in improving calibration of models. Detectability and sensitivity of a monitoring method is not just dependant on the technology but also the implementation mode when used in a specified calibration range and of course, different technologies will be suitable for different conditions and environments