To test the injection behaviour of CO2 into brine-saturated rock and to evaluate the dependence of geophysical properties on CO2 injection, flow and exposure experiments with brine and CO2 were performed on sandstone samples of the Stuttgart Formation representing potential reservoir rocks for CO2 storage. The sandstone samples studied are generally fine-grained with porosities between 17 and 32% and permeabilities between 1 and 100 mD. Additional batch experiments were performed to predict the long-term behaviour of geological CO2 storage. Reservoir rock samples were exposed over a period of several months to CO2-saturated reservoir fluid in high-pressure vessels under in situ temperature and pressure conditions. Petrophysical parameters, porosity and the pore radius distribution were investigated before and after the experiments by NMR (Nuclear Magnetic Resonance) relaxation and mercury injection. Most of the NMR measurements of the tested samples showed a slight increase of porosity and a higher proportion of large pores.

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Wandrey, M.; Morozova, D.; Zettlitzer, M.; Würdemann, H. (2010): Assessing drilling mud and technical fluid contamination in rock core and brine samples intended for microbiological monitoring at the CO2 storage site in Ketzin using fluorescent dye tracers. International Journal of Greenhouse Gas Control, 4, 6, 972-980.