Storage Processes

Injection of CO₂ and associated substances into a storage formation disturbs physical and chemical conditions in the subsurface resulting in disequilibria leading to thermal, fluid-dynamic, mechanical and chemical reactions. Some of these reactions are of geotechnical relevance, e.g. impacting injectivity, storage capacity, and security.

In order to identify and predict processes of geotechnical relevance, scientists and engineers of BGR

• examine rocks from the vicinity of natural CO₂ sources,
• calculate states, processes and reactions through computer simulations,
• carry out laboratory 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. Additionally, processes are coupled, e.g. chemical and fluid-dynamical processes.

Original (red) and geochemically altered (grey) Buntsandstein from a drill core Source: BGR

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.

Current Projects:

• CLUSTER Impacts of impurities in captured CO₂ streams from different emitters of a local cluster on transport, injection and storage

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Past Projects:

• CASTOR European CASTOR project on the capture and geological storage of CO₂
• CLEAN CO₂ Large-Scale Enhanced Gas Recovery in the Altmark Natural Gas Field
• GESTCO Geological Storage of CO₂ from Fossil Fuel Combustion
• DYNAMIS Towards Hydrogen Production with CO₂ Management
• Einfluss struktureller Heterogenitäten auf die Speicherkapzität von Kohlendioxid in Aquiferporenspeichern
• Regionale Druckauswirkung der CO₂-Speicherung in salinaren Aquiferen
• CO₂GEONET European Network of Excellence on Geological Storage of CO₂
• CSEGR Carbon Sequestration with Enhanced Gas Recovery
• CO₂Brim Mehrstufige und regionale Charakterisierung potenzieller CO₂-Speicherformationen unter besonderer Berücksichtigung von Soleaufstiegsrisiken
• CO₂BioPerm Einfluss biogeochemischer CO₂-Transformationsprozesse auf das langzeitige Permeabilitätsverhalten von Speicher- und Deckgesteinen sowie Bohrlochzementen
• COORAL CO₂ Purity for Capture and Storage
• CO2QUEST Techno-economic Assessment of CO₂ Quality Effect on its Storage and Transport
• ULTimateCO2 Understanding the long-term fate of geologically stored CO₂