D3.4 Monitoring plan, UK site

A plan is presented to monitor the SiteChar multi-store site for geological storage of carbon dioxide in the UK North Sea. A monitoring plan is a required component of a storage permit and underlies the ‘dry-run’ permit application for the UK site in the SiteChar project.  A storage permit area is defined based on maximum predicted extent of the injected CO₂ plume, the enclosing geological structure and hydrocarbon licence blocks. The monitoring proposed consists of surface- and well-based techniques to be deployed within the defined storage permit area. Monitoring is planned from the pre-injection period of baseline monitoring, a 20-year period of injection and a maximum post-injection period of 20 years. The monitoring plan is designed to allow earlier site closure subject to all available evidence indicating that the store CO₂ is completely and permanently contained. Monitoring techniques and their deployment are designed to meet regulators requirements, monitor any residual risks, meet agreed operating conditions and flag the need for corrective measures if storage conditions are not as predicted. A preliminary cost-benefit analysis study is applied as part of the tool selection process. A detailed feasibility study indicates 3D seismic surveying techniques are suitable to monitor the injected CO₂ gas.