The process starts with the pumping of CO2 at high pressure into an underground reservoir with specific geological features.  A layer of stable porous rock at the correct depth, often over 1km, is required for a suitable reservoir.  An impermeable layer of “cap” rock seals the porous layer preventing leakage to the surface.  The rock formations act as secure, natural traps, to hold the gases and liquids deep underground whether on land or at sea. 

Every CO2 geological site is unique in terms of geology and structure.  Two well known potential types of storage sites are depleted oil and gas reservoirs and deep saline formations.  Un-mineable coal seams are considered possible storage locations.

Image courtesy of Lawrence Berkley National Laboratory

Development of storage projects is typically conducted in 4 or 5 stages.  Site selection and development commences with geological characterization, reservoir simulation, well engineering and monitoring.  During the operational phase, gas is injected while monitoring continues.  At closure, and post-closure, all field facilities are closed and monitoring continues.

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