UKCCSC Meeting 18th April Nottingham Natural analogues of CO2 leakage from the Colorado Plateau Stuart Gilfillan, Stuart Haszeldine, Zoe Shipton and Mark Wilkinson

1
UKCCSC Meeting18th AprilNottinghamNatural
analogues of CO2 leakage from the Colorado
PlateauStuart Gilfillan, Stuart Haszeldine, Zoe
Shipton and Mark Wilkinson
2
Key Questions

• How do natural CO2 storage sites fail?
• - Faults, lithology, caprock seal and
  groundwater regime.
• What are the pathways of CO2 migration to the
  surface?
• - Can we predict/prevent leakage in engineered
  sites?
• How long does CO2 migration to the surface take?
• - CO2 needs to be stored for 10,000 years.
• Can leakage of CO2 be monitored and quantified?
• - Which chemical tracers can be used.
• - How effective are they at monitoring natural
  CO2 leakage?

3
Colorado Plateau
4
Colorado Plateau
Green River Seeps and Salt Wash fault zone, Utah
5
Colorado Plateau
Green River Seeps and Salt Wash fault zone, Utah

• Cold water springs and geysers driven by pressure
  of CO2.
• - Gas is 95 - 99 CO2- 0.5 - 3.5 N2- Trace
  noble gases.
• CO2 release from gt 80ka.
• Where does this water and CO2 originate from?
• How is this CO2 being transported to the surface?

Crystal geyser, Utah
6
Origin of the Water?

• Salinity of erupted water indicates migration of
  water from deep aquifer.

7
Origin of the Water?
Deep aquifer
Shallow aquifer
8
Origin of the CO2?
9
Origin of the CO2?
10
Origin of the CO2?
From Ballentine et al. 2002
Accumulate in groundwater
4He 21Ne 40Ar
In-situ production
Radiogenic Component
11
Origin of the CO2 CO2/3He ratio

• Mantle CO2/3He range 1 x 109 1 x 1010
• Measured from Mid Ocean Ridge Basalts - MORBs

12
Origin of the CO2 CO2/3He ratio
Above 1 x 1010 Crustal CO2
Mantle (MORB) range 1 x 109 1 x 1010
CO2/3He Ratio
Below 1 x 109 CO2 lost relative to 3He.
13
Origin of the CO2 CO2/3He ratio
1.00e12
Green River Seeps
1 - 16 Mantle CO2
1.00e11
1.00e10
Mantle (MORB) range 1 x 109 1 x 1010
Mantle (MORB) range 1 x 109 1 x 1010
CO2/3He Ratio
1.00e9
1.00e8
1.00e7
1.00e6
70
75
80
85
90
95
100
CO
Concentration ()
2

• Predominantly crustal derived CO2 erupted from
  the Green River seeps.
• Small mantle component ? 1 16

14
Conclusions
15
Other natural analogues of CO2 leakage

• Hurricane Fault, Utah
• Active, steeply dipping normal fault 250 km
  long, 2.5 km displacement.
• CO2 40C water discharges from fault zone.
• Noble gas and d13C (CO2) analysis underway.
• No evidence of a CO2 reservoir at depth.

Hurricane fault looking north www.skytrailsranch.c
om
16
Other natural analogues of CO2 leakage

• Hurricane Fault, Utah
• Active, steeply dipping normal fault 250 km
  long, 2.5 km displacement.
• CO2 40C water discharges from fault zone.
• Noble gas and d13C (CO2) analysis underway.
• No evidence of a CO2 reservoir at depth.
• St. Johns Dome
• Large natural CO2 reservoir (445 billion m3).
• CO2 rich surface seeps and travertines.
• Composition of deep gas and waters known.
• Can natural CO2 can be chemically tagged? e.g.
  using d13C(CO2) and/or noble gases.

17
St. Johns Dome Workflow

• Water samples collected from 18 surface seeps
• - 14C tritium for groundwater dating.
• - Solute chemistry.
• - Noble gas, d13C(CO2), d18O and dD isotopes.
• Compare composition of surface seeps to known
  chemistry of reservoir fluids.
• Use geochemical modeling to determine and
  quantify mineralogy changes as CO2 migrates.
• Reservoir models underway to investigate CO2
  migration pathways and timescales.

18
Summary

• How do natural CO2 storage sites fail?
• - Primary mechanism is migration along fault
  planes.
• What are the pathways of CO2 migration to the
  surface?
• - CO2 is dissolved into the groundwater and
  transported along faults.
• How long does CO2 migration to the surface take?
• - Unknown at present, dating of CO2 deposits
  will hopefully provide a timeframe.
• Can leakage of CO2 be monitored and quantified?
• - Yes, a baseline geochemical survey helps a lot!