When CO2 meets water in the subsurface, it is dissolved to form carbonic acid. Carbonic acid can react with the surrounding rock and in turn dissolve mineral components. This is how natural sparkling mineral waters form. The reactions can also cause new minerals to form. Because the rocks thus altered have different physical properties compared to the original rock, it is important to predict the impact of CO2 on the reservoir and cap rocks. For example, an increase of porosity due to chemical reactions within the reservoir rock might increase the storage capacity, while an increase of porosity in the cap rock could be a risk to the safe confinement of the stored CO2.
To prognose possible geotechnically relevant reactions of underground CO2 we
- examine rocks from the vicinity of natural CO2 vents
- calculate reactions through thermodynamic computer simulations
- carry out lab experiments under controlled conditions
To predict the conditions in industrial size storage projects, it is necessary to combine all three approaches, each of which sheds light on different aspects and dimensions of processes.
- CLEAN CO2 Large-Scale Enhanced Gas Recovery in the Altmark Natural Gas Field
- COORAL CO2 Purity for Capture and Storage
- CASTOR European CASTOR project on the capture and geological storage of CO2
- CO2GEONET European Network of Excellence on Geological Storage of CO2
- CO2STORE Saline Aquifers in Northeast Germany
- CSEGR Carbon Sequestration with Enhanced Gas Recovery
- NASCENT Natural Analogues for the Study of CO2 in the Geological Environment