Geologic Storage of CO 2 : Leakage Pathways and Environmental Risks Michael A. Celia, Catherine A. Peters, and Stefan Bachu Princeton University and Alberta Geological Survey May 2002
CO 2 Injection and Trapping Mechanisms Precipitated Carbonate Minerals ~800 m Confining Layer(s) Injection Well Supercritical CO 2 Dissolved CO 2 Stratigraphic Trapping Solubility Trapping Mineral Trapping Hydrodynamic Trapping
Research Questions How effective are the various trapping mechanisms? What is the likelihood and magnitude of CO 2 leakage? What are the environmental impacts of CO2 leakage? Today: Solubility trapping Today: Abandoned wells Today: Mammoth Mtn, and groundwater quality
Simulation of Injection of Supercritical CO 2 TOUGH2 Simulator Radial symmetry Isothermal conditions Confining layer permeability of 0.1 mD Target formation porosity 10% and permeability of 100 mD. 50 m 10 m 790 m CO 2 Brine CO 2 injection = 20 kg/s
Simulation of Injection of Supercritical CO 2 After 4 years of CO 2 injection CO 2 injection combined with injection of brine above the confining layer Radial distance [m] Depth [m] Mass of CO 2 /Volume [kg/m 3 ] Q brine = 40 kg/s Radial distance [m] Depth [m] Mass of CO 2 /Volume [kg/m 3 ]
Simulation of Injection of CO 2 Dissolved in Water After 1 year After 50 years seal Total Mass CO 2 injected = 3.1x10 7 kg seal Total Mass CO 2 injected = 1.2x10 9 kg Mass of CO 2 /Volume [kg/m 3 ]
Leakage Pathways and Trapping Mechanisms Injected Carbon Dioxide Surface Ecosystems Confining Layer(s) Atmosphere lateral migration Localized vertical migration fractures, faults, wells Potable Water
Leakage Pathways: Abandoned Wells in the Alberta Basin
Simulation of leakage through a single abandoned well Permeability of a typical well cement ~ m 2 Permeability of a medium sand ~ m 2 Depth [m]
Potential Effect on GW Quality distance, m 2 yr. 4 yr. 6 yr. 8 yr. 10 yr. groundwater flow CO 2 leakage deep brine aquifer drinking-water aquifer 0.0E E E E E-07 Pb 2+ concentration, mol/L
On the Long Valley Caldera in eastern California Soil gas surveys revealed CO 2 concentrations as high as 95%. (CO 2 concentrations > 10% toxic to humans.) Mammoth Mountain
Changes in Metal Uptake in Plants Elevated soil CO 2 Ca 1989 Zn Mn c b 2001 Ambient soil CO 2 Mn Zn Ca
Acknowledgements Funding from BP and Ford. Equations of State: R. Bruant TOUGH2 Simulations: A. Guswa, S. Gasda Leakage Estimates: A. Duguid Groundwater Simulations: P. Jaffe, S. Wang Mammoth Mountain: S. Myneni, S.J. White