In the laboratories of the CO₂ Seals research groups, geologists, mineralogists and physicists study the effects of CO₂ on the properties of rocks overlying potential geological reservoirs (caprocks). Experiments are conducted at temperatures and pressures similar to those prevailing between 800 and 3000 m depth. This interval is the typical depth for CO₂ storage reservoirs.

Pure minerals, mineral mixtures and core samples from outcrops or deep wells are used to investigate how chemical and physical interactions with CO₂ and CO₂ saturated brines affect the sealing efficiency (fluid transport properties, mechanical stability) of different types of caprocks (lithotypes). (To investigate the chemical and physical interactions of the CO₂ and CO₂ saturated brines with different types of caprocks, pure minerals, mineral mixtures and core samples are used. Those samples originate from deep wells or from outcrops.) Of particular interest is the role of faults and fracture zones. Major research topics of the RWTH Aachen University group:

• Mineral alterations associated with CO₂-brine-rock interactions
• Changes of petrophysical and fluid transport behavior (effective permeability, capillary entry pressure, effective diffusion coefficients)
• CO₂ sorption capacity of the caprock

Major research topics of the Karlsruhe Institute of Technology (KIT) group:

• Migration of CO₂ along faults and damage zones in caprock
• Reactivity of caprocks under the influence of CO₂-rich formation waters
• Change of the mechanical properties of fault zones as a function of the degree of alteration

Numerical modeling of reactive transport and rock mechanics are used to analyze and interpret the experimental results. This helps to get an improved understanding of the mechanisms and effects of the interaction between CO₂ and caprocks. The models are applied to predict processes on the size- and time-scale of geological CO₂ storage reservoirs. Home