Geologic Storage of CO2: Leakage Pathways and Environmental RisksMichael A. Celia, Catherine A. Peters, andStefan Bachu

Princeton University

andAlberta Geological Survey

May 2002

CO2 Injection and Trapping Mechanisms

Precipitated Carbonate Minerals

~800 mConfining Layer(s)

Injection Well

SupercriticalCO2

Dissolved CO2

Stratigraphic Trapping

Solubility Trapping

Mineral Trapping

Hydrodynamic Trapping

Research Questions

• How effective are the various trapping mechanisms?

• What is the likelihood and magnitude of CO2 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 CO2

• 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

CO2

Brine

CO2 injection= 20 kg/s

Simulation of Injection of Supercritical CO2

After 4 years of CO2 injection

CO2 injection combined with injection of brine above the confining layer

Radial distance [m]

De

pth

[m

]

Mass of CO2/Volume [kg/m3]

Qbrine = 40 kg/s

Radial distance [m]

De

pth

[m

]

Mass of CO2/Volume [kg/m3]

Simulation of Injection of CO2

Dissolved in Water

• After 1 year • After 50 years

seal

Total Mass CO2 injected = 3.1x107 kg

seal

Total Mass CO2 injected = 1.2x109 kg

Mass of CO2/Volume [kg/m3] Mass of CO2/Volume [kg/m3]

Leakage Pathways and

Trapping Mechanisms

Injected Carbon Dioxide

SurfaceEcosystems

Confining Layer(s)

Atmosphere

lateral migration

Localized vertical migration

fractures,faults, wells

Potable Water

Leakage Pathways:Abandoned Wells in the Alberta Basin

0500100015002000250030003500400045005000

1883

1908

1917

1926

1935

1944

1953

1962

1971

1980

1989

1998

year abandoned

num

ber

of w

ells

Simulation of leakage through a single abandoned well

• Permeability of a typical well cement ~ 10-17 m2

• Permeability of a medium sand ~ 10-10 m2

De

pth

[m

]

Rate of CO2 Leakage [kg/s]

0

1

2

3

4

1.00E-17 1.00E-15 1.00E-13 1.00E-11 1.00E-09

Permeability [m^2]

Potential Effect on GW Quality

-50 50 150 250

distance, m

2 yr.

4 yr.

6 yr.

8 yr.

10 yr.

groundwater flow

CO2 leakage

deep brine aquifer

drinking-water aquifer

0.0E+00

3.0E-08

6.0E-08

9.0E-08

1.2E-07

Pb2

+ co

nce

ntr

atio

n, m

ol/L

• On the Long Valley Caldera in eastern California

• Soil gas surveys revealed CO2 concentrations as high as 95%. (CO2 concentrations > 10% toxic to humans.)

Mammoth Mountain

Changes in Metal Uptake in Plants

Elevated soil CO2 Ca1989

Zn

Mn

c b

2001

Ambient soil CO2

Mn

Zn

Ca

1989 2001

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