Storing CO2 underground, is based on a process that has trapped CO2, oil and gas for millions of years. Both oil and gas fields and deep saline aquifers have the key geological features required for CO2 storage: a layer of porous rock to absorb CO2 and an impermeable layer of cap rock which seals the porous layer underneath, trapping CO2. The safe and permanent storage of CO2 is part of the most important factors in ensuring CCS can achieve its potential as a key climate change mitigating technology. As such the Network projects have been undertaking extensive subsurface site selection, characterisation, and monitoring and assurance processes.


Compostilla: Two sites had been selected for further assessment, the “Duero site(s)” and the “Andorra site(s)”. Both sites are onshore deep saline aquifers. Hontomín is the research pilot, developed within Compostilla project, devoted to real scale experiments, investigating cost-effective operations such as slim drilling technologies, testing of various injection strategies, and deployment of a large set of monitoring technologies at depth and at the surface.

Don Valley: The reservoir consists of sandstones located on a closed structure in the Southern North Sea (Bunter formation). It is an offshore deep saline aquifer. Milestone decision in favour of saline storage site known as 5/42 with drilling appraisal was scheduled and subsequently undertaken in the summer of 2013.

ROAD: Offshore depleting gas field P18, approximately 20 kilometres off the coast (North Sea). The gas reservoirs are at a depth of around 3,500 meters. The P18 field consists of three reservoir blocks, the P18-2, P18-4 and P18-6 blocks. P18-4 is the reservoir targeted by the project.

Sleipner: Offshore deep saline aquifer (North Sea). The highly porous and extremely permeable Utsira sands are used to inject CO2 since 1996. In terms of characterisation the project has moved on to the next phase, starting injection of CO2 from the Gudrun field on Q1 of 2014.