Key Questions

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UKCCSC MeetingUKCCSC Meeting1818thth April April

NottinghamNottingham

Natural analogues of CONatural analogues of CO22 leakage leakage

from the Colorado Plateaufrom the Colorado Plateau

Stuart Gilfillan, Stuart Haszeldine, Zoe Shipton and Stuart Gilfillan, Stuart Haszeldine, Zoe Shipton and Mark WilkinsonMark Wilkinson

School of GeoSciencesSchool of GeoSciencesSubsurface Research GroupSubsurface Research Group

Key QuestionsKey Questions

1. How do natural CO2 storage sites fail?

- Faults, lithology, caprock seal and groundwater regime.

2. What are the pathways of CO2 migration to the surface?

- Can we predict/prevent leakage in engineered sites?

3. How long does CO2 migration to the surface take?

- CO2 needs to be stored for 10,000 years.

4. Can leakage of CO2 be monitored and quantified?

- Which chemical tracers can be used.

- How effective are they at monitoring natural CO2 leakage?

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Colorado PlateauColorado Plateau

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Colorado PlateauColorado PlateauGreen River Seeps and Salt

Wash fault zone, Utah

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- 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 > 80ka.

- Where does this water and CO2

originate from?

- How is this CO2 being transported

to the surface?

Green River Seeps and Salt

Wash fault zone, Utah

Crystal geyser, Utah

Colorado PlateauColorado Plateau

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Origin of the Water?Origin of the Water?

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

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Deepaquifer

Shallowaquifer

Origin of the Water?Origin of the Water?

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From Ballentine et al. 2002

Magmatic ComponentMagmatic Component

33HeHe

Origin of the COOrigin of the CO22??

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From Ballentine et al. 2002

Magmatic ComponentMagmatic Component

33HeHe

Atmospheric ComponentAtmospheric Component

AquiferAquifer RechargeRecharge2020NeNe3636ArAr8484KrKr

Formation WaterFormation Water

Origin of the COOrigin of the CO22??

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From Ballentine et al. 2002

Magmatic ComponentMagmatic Component

33HeHe

RadiogenicRadiogenicComponentComponent

In-situ In-situ productionproduction

44HeHe2121NeNe4040ArAr

Atmospheric ComponentAtmospheric Component

AquiferAquifer RechargeRecharge2020NeNe3636ArAr8484KrKr

Formation WaterFormation Water

Accumulate Accumulate in groundwaterin groundwater

Origin of the COOrigin of the CO22??

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Origin of the COOrigin of the CO22 – CO – CO22//33He ratioHe ratio

• Mantle CO2/3He range: 1 x 109 – 1 x 1010

• Measured from Mid Ocean Ridge Basalts - MORBs

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70 75 80 85 90 95 1001.00e+6

1.00e+7

1.00e+8

1.00e+9

1.00e+10

1.00e+11

1.00e+12

CO2 Concentration (%)

Mantle (MORB) range: 1 x 10Mantle (MORB) range: 1 x 1099 – 1 x 10 – 1 x 101010

Above 1 x 10Above 1 x 101010::

Crustal COCrustal CO22

Below 1 x 10Below 1 x 1099: CO: CO22

lost relative to lost relative to 33He.He.

Origin of the COOrigin of the CO22 – CO – CO22//33He ratioHe ratioC

O2/3

He

Rat

io

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• Predominantly crustal derived CO2 erupted from the Green River seeps.

• Small mantle component → 1 – 16%

Mantle (MORB) range: 1 x 10Mantle (MORB) range: 1 x 1099 – 1 x 10 – 1 x 101010

1 - 16%

Mantle CO2

Origin of the COOrigin of the CO22 – CO – CO22//33He ratioHe ratio

70 75 80 85 90 95 1001.00e+6

1.00e+7

1.00e+8

1.00e+9

1.00e+10

1.00e+11

1.00e+12Green River Seeps

CO2 Concentration (%)

CO

2/3

He

Rat

io

Mantle (MORB) range: 1 x 10Mantle (MORB) range: 1 x 1099 – 1 x 10 – 1 x 101010

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ConclusionsConclusions

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Other natural analogues of COOther natural analogues of CO2 2 leakageleakageHurricane Fault, Utah

- Active, steeply dipping normal fault ~ 250 km long,

~2.5 km displacement.

- CO2 & 40°C water discharges from fault zone.

- Noble gas and δ13C (CO2) analysis underway.

- No evidence of a CO2 reservoir at depth.

Hurricane fault looking north www.skytrailsranch.com

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Other natural analogues of COOther natural analogues of CO2 2 leakageleakageHurricane Fault, Utah

- Active, steeply dipping normal fault ~ 250 km long,

~2.5 km displacement.

- CO2 & 40°C water discharges from fault zone.

- Noble gas and δ13C (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 δ13C(CO2) and/or noble gases.

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St. Johns Dome WorkflowSt. Johns Dome Workflow

- Water samples collected from 18 surface seeps

- 14C & tritium for groundwater dating.

- Solute chemistry.

- Noble gas, δ13C(CO2), δ18O and δD 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.

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SummarySummary

1. How do natural CO2 storage sites fail?

- Primary mechanism is migration along fault planes.

2. What are the pathways of CO2 migration to the

surface?

- CO2 is dissolved into the groundwater and

transported along faults.

3. How long does CO2 migration to the surface take?

- Unknown at present, dating of CO2 deposits will

hopefully provide a timeframe.

4. Can leakage of CO2 be monitored and quantified?

- Yes, a baseline geochemical survey helps a lot!