Ale Hakala Presentation
Transcript of Ale Hakala Presentation
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Geochemistry of CO2 Storage
Alexandra HakalaGeosciences Division, Office of Research and Development
National Energy Technology Laboratory
Pittsburgh, PA
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Geochemistry plays an important role in all
aspects of a geological CO2 sequestrationsystem
• Monitoring techniques
• Groundwater aquifers
– Liability issues
– EPA Class VI rules (also
includes injection well integrity)
• Other subsurface resources
• Seals: Wells and Natural Rocks
• Storage formation
– CO2 plume behavior
– Long-term permeability and
porosity
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http://acmg.seas.harvard.edu/people/faculty/djj/book/bookchap6-18.gif
• Primary considerations for CO2 geochemical effects include:
– Mineral dissolution
– Metal and other trace element mobility
Primary focus is on carbonate geochemistry
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CO2 solubility in water changes with salinity,
pressure, temperature
• Dealing with supercritical CO2 at depth
– Behavior of CO2 and geologic fluids within the reservoir will differ
from shallow systems due to P, T effects on CO2 solubility
• Need to account for CO2 thermophysical behavior both under
storage formation conditions for predicting reservoir behavior,
and in all aspects of the system when performing site and risk
assessments
Duan, Z. and Sun, R. An improved model calculating CO2 solubility in pure water and aqueous NaCl solutions from 273 to 533 K and from 0 to 2000 bar. Chemical Geology 193 (2003) 257-271.
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A variety of reactive materials are present in
all areas of a sequestration system
• Solids
– Sandstones
– Carbonates
– Shale
– Basalts
– Cement
– Steel
• Fluids
– Brine and Saline
fluids
– Oil – Low-TDS waters
Mt. Simon Sandstone Cores
(MRCSP / Indiana Geologic Survey)
Basalt Cores(Big Sky)
Lower Tuscaloosa Sandstone
(in reactors)
(SECARB/TX-BEG)
Class H Well Cement Reacted with
H 2 S and CO2
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A variety of pressure, temperature and
baseline geochemical conditions exist ingeologic CO2 sequestration systems
• Carbonate chemistry, pH effects primary focus; also solvent
effects (e.g., organics)
• Potential co-constituents of a CO2 stream
– Can the system handle trace amounts of H2S, SO2, O2,
byproducts of CO2 capture systems?
• P,T conditions will affect thermodynamics and kinetics of
different reaction processes
– Ion exchange, sorption, dissolution, precipitation
• Also need to consider possible secondary geochemical effectsand geochemical monitoring tools
– Redox, microbiology, organics, isotope geochemistry
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Geochemistry plays an important role in all
aspects of a geological CO2 sequestration
system
• Monitoring techniques
• Groundwater aquifers
– Liability issues
– EPA Class VI rules (also
includes injection well integrity)
• Other subsurface resources
• Seals: Wells and Natural Rocks
• Storage formation
– CO2 plume behavior
– Long-term permeability and
porosity
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Lower Tuscaloosa Sandstone
(SECARB Cranfield Injection Site)
• Minimal short-term geochemical
reactivity
– Clay protection of carbonates
– Longer term reactions may occur
Lab Experiment DataField Experiment Data
Lu, J.; Kharaka, Y.; Thorsden, J. J.; Horita, J.; Karamalidis, A.; Griffith, C.; Hakala, J. A.; Ambats, G.; Cole, D. R.; Phelps, T. J.; Manning, M. A.; Cook, P. J.;
Hovorka, S. Geochemical interactions in the Lower Tuscaloosa reservoir at the Cranfield CO2 sequestration site, Mississippi, USA Under Review.
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Which microbial communities affect geochemical processes in CO2 storageformations and in shallow groundwaters? What geomicrobiological processes
need to be included as part of predictive modeling efforts?
Geochemical Reactions – Microbiological Studies
Wallula Pilot Well Basalt (WA)(BSCSP)
Lower Tuscaloosa Sandstone (MS)(SECARB / TX Bureau of
Economic Geology)
Wellington Oil Field (KS)(SWP / Kansas Geological Survey)
• Characterize the influence of microbes on supercritical CO2 storagein candidate storage formations (basalt, sandstone, depleted oil
reservoirs)
• Determine how native microbes respond to supercritical CO2
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Science base enables a more reliable assessment
of the impact of critical processes at the systemlevel.
CO2+brine dissolves
hydrated cement
Based on conservative assumptions…
• Avoid areas with wellbores
– avoid depleted oil and gas reservoirs
• Require use of CO2-resistant cement
– higher costs & limited field-use experience
Based on limited experience base… • Potentially underestimate long-term costs
– liability; wellbore maintenance; etc.
?
wellbore permeability
will increase
wellbore permeability
will not increase
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CO2-Brine-Cement and CO2-Cementreactions behave differently
Kutchko, Strazisar, Dzomback, Lowry, & Thaulow, Environmental Science and Technology, (2007)
Supercritical CO2
CO2
saturated brine
Unaltered cement
Altered
cement
CaCO3(s)barrier (2)
Degraded Zone (3)
Propagation of Fronts
Ca(OH)2 depleted
zone (1)
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Different reaction effects are observed when H2S is presentas a co-constituent in the laboratory
Kutchko, Strazisar, Hawthorne, Lopano, Miller, Hakala, Guthrie, Intl J. GHG Control (2011)
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Prediction of groundwater aquifer response
complicated due to system heterogeneities
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Laboratory batch reaction experiments with
Gulf Coast Aquifer samples• Observed change in pH values,
mineral morphology after CO2
reaction with samples
• Elevation of Type I and II
cations with initial CO2 flux
– Type I reached equilibrium,
but Type II declined over time(sorption effect?)
• Rapid reactions of carbonate
minerals contribute toobserved changes in solution
chemistry
Lu, Partin, Hovorka, Wong, Environ. Earth Sci. (2010)
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Shallow aquifer samples from Illinois and Texas show CO2 reaction results similar to the Gulf Coast Aquifer
• Laboratory experimental conditions using natural aquifer core samples• pH decline after CO2 exposure
• Increase in Type I cations, some Type II cations (e.g., Fe)
• Increase in EPA-regulated elements, although concentrations remain
below the MCLs for U and As
Little and Jackson, Environ. Sci. Technol. (2010)
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Shallow CO2 injection groundwater monitoring
at the ZERT site in Bozeman, MT
• Rapid, systematic pH
changes (7.0 – 5.6),
alkalinity, and electrical
conductance following
CO2 injection
• Increase in Ca, Mg, Feand Mn following
injection
• Dissolution of carbonate
minerals and
desorption-ion exchangefrom lowered pH values
Kharaka, Thorsden, Kakouros, Ambats, Herkelrath, Beers, Birkholzer, Apps, Spycher, Zheng, Trautz, Rauch, Gullickson (2010) Environ. Earth Sci.
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Modeling to predict aquifer-specific CO2-inducedgeochemical changes
• Mineralogical properties of receiving aquifer dictate observed result of
CO2 migration into shallow aquifers
• CO2 gas dissolution into groundwater and subsequent reactions will
drive the evolution of carbonate chemistry and pH in the aquifer
Wilkin and DiGiulio, Environ. Sci. Technol. (2010)
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Ongoing collaboration between NETL-ORD, University of Pittsburgh, and LANL
Natural analog sites used to study geochemistry of
aquifers with elevated CO2 and salinity• Natural analogs
– CO2 naturally upwelling throughshallow aquifer in volcanic or geothermal settings
• Rapid release pathways alongfaults
• Diffuse CO2 rising and flowingthrough aquifer
• High alkalinity and carbonatedissolution buffers pH changes dueto carbonate influx Keating et al. (2009)Environ. Earth Sci.
• Buffering capacity and unknowngeochemical reactions complicate
modeling efforts
Keating et al. (2009) Environ. Earth Sci.
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Chimayo aquifer sample collection from surface outcrops (March 2009)
0.1 km
Roadcut Bedplane 2 Yellow
(Lithosome A: silty-clayeyfine sand)
Roadcut Bedplane 1 Gray
(Interbedded B & A, fine-
grained)
Streamcut 2 Green (Lithosome
B, sand and gravel channel
fills)
Streamcut 1 Blue (Lower
Lithosome B: silt, clay, fine
sand floodplain sediment)
Keating et al. (2009) Environ. Earth Sci.
Keating et al. (2009) Environ. Earth Sci.
Google Earth
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What is present in Chimayo sediments? If wedetermine what is present, can this information be
used in reactive transport simulations?
Tools for identifying trace element content
• Scanning Electron Microscopy
– Often, trace elements not concentrated enough toobserve in elemental maps
• X-ray Absorption Spectroscopy
– Ideal for identifying speciation and distribution of elements in environmental samples, but limited
access to facilities
• Sequential Extraction Techniques
– Relatively simple to perform and may yield usefulinformation, but potential limitations with selectivity
Ongoing collaboration between NETL-ORD, University of Pittsburgh, and LANL
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Analysis of solids (Q-XRD and SEM) show quartz and clays withfeldspars, kaolinite, calcite, hematite, other phases
Q-XRD, wt%
Quartz
Clay coating/
weathering
keV
876543210
o u n t s
4,000
3,000
2,000
1,000
0
O
S
Ca
CaSr Ba
Ba
Ba
Ba
Ba, Sr and Ca inrandomly distributed phase (RCBP2-G)
Ongoing collaboration between NETL-ORD, University of Pittsburgh, and LANL
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Sequential extractions, CO2 batch reactions and synchrotroncharacterization provide information on trace elements
0
0.01
0.02
0.03
0.04
As U
Exchangeables/Carbonates
MnOxides (Reducibles)
FeOxides (Reducibles)
Oxidizables
R a t i o o f [ E x t r a c t i o n S t e p ] / [ T o t a l ]
Fe K α As K α /Pb Lα 1
350 µm x 350 µm
As(III)
As(V)
Ongoing collaboration between NETL-ORD, University of Pittsburgh, and LANL
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