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Abstract

There has been growing interests in recent years for the safe underground storage of carbon dioxide (CO2) as a potential technology for preventing this greenhouse gas from entering the atmosphere. As suitable locations for geological storage may be diverse, the applicability of various geodetic and geophysical methods for surveillance and monitoring purposes must be investigated. In this paper, we evaluate the ground surface displacement at the Ketzin pilot site for CO2 storage in Germany, using satellite-based measurements and hydromechanical simulations. The InSAR observations, using more than four years of TerraSAR-X data from 2009 to 2013, reflect the stability of the Ketzin pilot site (long-term velocity <0.5 mm/year) in conjunction with the accumulated CO2 volume in the reservoir. This can be due to the low overall pressure change, with a maximum of 16 bar, which is not causing significant surface displacement. However, such overall stability can be interrupted temporarily, as detected within the InSAR time series for a distinct period of noninjection from May to December 2012 (subsidence of 2.8 mm). This is supported by our hydromechanical simulation results, exhibiting a maximum ground surface subsidence of approximately 1 mm during this period, and by a comparison with variations in bottomhole pressure, indicating a positive correlation of 80%.