D4.6 – Dry-run licence application, Danish site

The objective for the Vedsted site was to complete a site characterisation sufficiently comprehensive to fulfil a ‘dry-run’ application for a storage permit.  This has been achieved including geological, dynamical, geomechanical characterisation and monitoring strategy development.  

The research has in particular investigated different ways to supplement the sparse data-set usually available from saline aquifers only investigated by un-successful hydrocarbon exploration. By incorporating all existing geological knowledge on a regional scale a site model was constructed that could be used with enough confidence to characterise the storage complex and the dynamic behaviour during the injection operation.   

Dynamic modelling governed the design of a monitoring program and assured the best risk management. It was assessed that geophysical monitoring techniques are most suited for monitoring the site together with monitoring well(s). Modelling the extent of the CO2 distribution also helped designing and acquiring a baseline study for any CO2 leakage. Two soil gas surveys were acquired during the project and revealed the natural variation in the sampled soil gasses.

There was a special interest in exploring the impact on the immediate region, especially pressure development in the surrounding saline aquifer and any possible effects in the overlying layers. Pressure relief can be managed by excess water production.

Risk analysis carried out for the storage project pointed out the old exploration well, Vedsted-1, to be a potential risk for leakage. The well was not abandoned to fulfil present day regulations, mostly due to insufficient cement plugs. A comprehensive well integrity study concluded that a well re-intervention to proper plug and abandon the well was must suitable and cost efficient.