Large-scale carbon sequestration involves capturing carbon dioxide emitted from power plants and injecting it into underground reservoirs for long-term storage. Leakage from these storage reservoirs could lead to groundwater contamination, requiring that the spread of CO2 be monitored during and after injection. Seismic surveys are one key monitoring tool, but inferring the distribution CO2 deep in the subsurface from seismic reflection data can be very challenging.
In a new study from the University of Cambridge, Peter Dudfield and Andy Woods assess some of these challenges. Using a simple model for CO2 spreading, they study the extent to which the threshol of seismic detection limits information that can be extracted from seismic data. They show that seismic data alone is usually not sufficient to uniquely estimate the CO2 distribution, even in an idealized scenario, but that data of reservoir pressure near the injection site can help to constrain these estimates. This is a useful step forward in our understanding of the capabilities and limitations of monitoring technology.
P. Dudfield and A. W. Woods. On the use of seismic data to monitor the injection of CO2 into a layered aquifer. Earth and Planetary Science Letters, 368:132–143, 2013.