To validate model predictions and test critical hypotheses, CO2 trapping and leakage processes must be studied at the pressures and long length scales operative in the context of geologic sequestration. In a partnership between Princeton University and the Lawrence Berkeley National Laboratory funded by the U.S. National Science Foundation, lead investigator Catherine Peters and principal investigators Jean Prevost and George Scherer are planning for DUSEL CO2, a facility for experimental study of geologic carbon sequestration. The proposed facility will be part of DUSEL, the deep underground laboratory being built in the Homestake mine in South Dakota (Figure 9). DUSEL will be a world-class facility with access to depths of more than 2225 meters (7,400 ft), and will provide capabilities for research in physics, geosciences, biology, and engineering. At present, the facility is being designed and the portfolio of experiments is being prioritized. Construction is expected to start in 2013.

Figure 9. Catherine Peters (foreground) in the Homestake Mine, future home of the DUSEL CO2 facility.

The planned DUSEL CO2 facility will enable study of CO2 vertical migration and trapping mechanisms on realistic length scales and enable an unprecedented level of experimental control and monitoring capabilities. The existing matrix of shafts and drifts in the mine will be exploited for construction of vertical half-kilometer column pressure vessels in which CO2 flow can be observed. Instrumentation will enable detailed monitoring of flow, pressure, temperature, brine composition, CO2 concentrations, phase changes, geomechanics, and microbial activity. Fill materials will mimic sedimentary layering, as well as cements in plugged wells.

As part of the initial experiments, the researchers plan to simulate a leak in which CO2 changes from a supercritical fluid to a subcritical gas during upflow over tens to hundreds of meters. They will also test for possible acceleration in CO2 flow due to increasing buoyancy and examine the interactions of CO2 with cap-rocks and well cements to determine whether CO2 will enlarge flow pathways or cause self-sealing. Finally, the team will investigate the effects of anaerobic, thermophilic bacteria on CO2 conversion to methane and carbonate. The findings from these unique experiments will advance carbon management technology worldwide and help reduce global greenhouse gas emissions.