Experimental study on the impact of H2S and H2SO4 in CO2 on five different sealant compositions under conditions relevant for geological CO2-storage
Reinier van Noort (Institute for Energy Technology)
Gaute Svenningsen (Institute for Energy Technology)
Kai Li (TU Delft - Applied Geophysics and Petrophysics, Karlsruhe Institut für Technologie)
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Abstract
This paper reports exposure of five different sealants to simulated well conditions with supercritical CO2 containing H2S or H2SO4 as impurities. Three of these sealants are based on Portland Cement, while the other two are based on Calcium Aluminate Cement, and a rock-based geopolymer specifically developed for Geological CO2 Storage (GCS). The impact of the impurities on these sealants was assessed through scanning electron microscopy with energy-dispersive X-ray spectroscopy, computed tomography scanning, and fluid chemical analysis, and compared to previous research where the same five sealants were exposed to clean CO2 under otherwise identical conditions.
The results show that during exposure to CO2-saturated water, the presence of H2S mostly resulted in enhanced sealant alteration depths, and reduced carbonate precipitation. During exposure to wet supercritical CO2, the presence of H2S or H2SO4 resulted in reduced carbonate precipitation, and enhanced alteration depths in some (H2S) or all (H2SO4) sealants. Additionally, relatively minor degradation was observed in the outer 100–200 μm of samples exposed in the presence of H2SO4. Overall, the impacts of impurities were more pronounced for sealants that were more affected by exposure to clean CO2.
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