Dating CO2 leakage rates from a natural analogue for CO2 storageZoe Shipton (GU), Neil Burnside (GU/SUERC), Rob Ellam (SUERC), Ben Dockrill (Chevron)
CO2 Capture Project Statoil, Norsk Hydro, Shell, BP, Eni, EnCanaSuncor, ChevronTexaco, Norway, EU, US DOE
Geological setting
Shipton et al. 2005
Present LeakageOil seep
Past Leakage
Dockrill 2006, Dockrill and Shipton 2008
LGWF
MF
SWFs
Dockrill and Shipton 2008, Vrolijk et al. 2006
Individual mounds active for up to ~10ka
Evidence of reactivation of these pathways with 3 distinct mounds ranging in age of ~45ka
Flow pathways switch repeatedly through time
Leak points spread along the faults as pathways become completely sealed
Flow not continuous - periods of inactivity indicate intermittent flow regime to the surface
Volumetric estimates
min. LGW travertine volume 1.5 x 105 m3 = 4.3 x 108 kg CO2
if 10% of CO2 trapped in travertine ~ 1.9 x 109
kg CO2 leaked over ~80-110 k yrs
Time- averaged flux > 0.84 kg/m2/yr = 0.6μmol/m2/s forest floor 2 to 20μmol/m2/s (Drewitt et al., 2002) Mammoth Mtn tree kill avg 400μmol/m2/s (Benson & Hepple
05)
Gouveia et al. (2005) Crystal Geyser emits CO2 ~ 12 ktonnes/yearRecent increase due to drilling?Constraints on volume through time from new dates
combined CO2 storage capacity of fault-sealed traps ~ 0.6 - 6.3 MtDependent on saturation state and density of CO2Assuming leakage confined to above trap
leak rate of over ~ 0.2% to 1.9% every 500 yrs
Natural CO2 reservoirs in Utah
= laboratory to study leakage of CO2
natural springs boreholeselevated soil gas?
Observed changes in flow pattern may be caused by:
• sealing of fault pathways by carbonate precipitation
• changes in stress on faults or regional hydrology
~ 30 to 300% of total trap capacity leaked over 110 kyrs
What leak rate acceptable for industrial storage?