co 2 storage in saline aquifers
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Geological CO2 Storage Research ProgramAnnual Review Meeting
Austin, TX • November 30, 2007
CO2 Storage in Saline Aquifers
Mac BurtonRepresenting Dr. Steven L. Bryant
AndGeological CO2 Storage Research Program
Stabilizing Greenhouse Gas Emissions is a World-Scale Task
Current annual emission as carbon 7 GT
2050 annual emission (Business As Usual
Scenario)14 GT
Emission cuts/CO2 removal needed for
stabilization7 GT
INDUSTRY 29%
ELECTRICITY 38%
TRANSPORT 33%
Meaningful Mitigation of GHG Emissions will Require Geologic Sequestration (plus several other technologies simultaneously)
Each option would
remove 1 Gt carbon/year
Option Volume
Replace coal-fired electricity generation
By gas-fired 1400 GW
By wind 70 × today
By solar 1000 × today
By nuclear 700 1GW plants (2 × today)
Geological storage 3500 Sleipner projects
Hydrogen for transport 1 billion cars
Double fuel economy of motor fleet 2 billion cars @ 60 mpg
Biomass fuel from plants Area size of US agriculture
Meaningful Geologic Sequestration will Require a New Industry Comparable in Size to Current Oil & Gas Industry
Conversions between CO2 fluxes
1 “wedge” or Gt
Introduced by Pacala and Socolow (2004)
109 Metric tons carbon/y
3.7109
Metric tons CO2/y
190 BCFD CO2 Billion (109) standard cubic feet per day
105 MMBD CO2
Million barrels per day at typical deep aquifer conditions
Global gas production in 2006
277 BCFD
Global oil production in 2006
81.7 MMBD
General Overview of Geologic Storage in Deep Saline Aquifer
• Storage Mechanisms and General Plume Prediction- Dissolution and Capillary Trapping- Structural Trapping and Mineral- Time to Reach Seal and Lateral Extent
• Injection Strategies- Well Design- Reservoir Characterization
• Leakage from Natural and Man-Made Features- Leaking Faults- Leaking Top Seal- Leaking Wells
Standard Evaluation Techniques
Standard Evaluation Techniques
Requires New Evaluation Techniques and Science
Leakage of CO2 can pose a risk to:oUnderground AssetsoHealth Safety & EnvironmentoAtmosphere (Emission Credits)
Wells and faults are primary potential leakage
pathways
Why is Our Work in the Subsurface Important?
Two Examples of Importance of Our Work
Example #1: Active Well Leak and AbandonNumber of Wells in Gulf of Mexico with SCP
600 400 200 0
% of Wells with SCP0 10 20 30 40 50
Bourgoyne et al, MMS report
Nicot et al, 2006
5% to 30% of Active Wells per Field in
Gulf of Mexico have Leaks that Run to
the Surface
Hundreds of Wells are Abandon in the Gulf of Mexico each
Year;
Wells in the Gulf are Few in Number Compared to On-
shore
Example #2: Injection Design
DEP
TH
Pressure profile in aquifer
Pressure profile in well
PRESSURE
Geological CO2 Storage Research ProgramAnnual Review Meeting
Austin, TX • November 30, 2007
Surface Dissolution:
Implementation Costs and Technical Challenges
Mac BurtonSteven Bryant
Key Findings
• Surface dissolution technology increases the available target aquifer space. Where?- Shallower aquifers - Aquifers with poor seal quality
• Operational and capital costs for surface dissolution are larger but comparable in magnitude to those for standard approach.
• Surface dissolution may be attractive where the costs of insuring against buoyancy-driven CO2 leakage exceed these additional costs.
• Adds reasonable technology or options to our arsenal.
Motivations for Alternate CO2 Storage Strategies in Saline Aquifers
• Cheap Solution• Simple Solution• Safe Solution
We choose to look at a strategy that will:• Lower Risk Option• Address Technical Subsurface Challenges• Adds to Current Technology or Expanding our Options
Standard Approach to Sequestration-Retrofitting Coal-Fired Power Plant
STANDARD APPROACH
Costs for Standard Approach toAquifer SequestrationCosts of Standard Approach in for
Carbon Sequestration in Saline Aquifer
Process Operationala Capitalb
Capture 17%$500k-$1,000k
Compress and Inject 10%
Monitoring Buoyancy 0.5% $0
Buoyant CO2 Liability TBD $0
a % of Total Power Plant Capacity b per MW of Power Plant Capacity TBD = to be determined
Sources: Dr. Rochelle’s presentation to Dr. Bryant research review,
and Remediation of Leakage from CO2 Storage Reservoirs, IEA GHG Programme
Standard Approach to Saline Aquifer:Technical Challenges
• Buoyant Migration- Monitoring for Hundreds of Years- Interaction with Faults, Seals, and Existing Wells- Liability for Storage: Cost and Probability of
• Remediation• Lost Emission Credit• Damage to Subsurface Assets
• Injectivity- Reaching Pressure Limit In Closed Aquifer- Relative Permeability and Capillary Pressure
Surface Dissolution Approach to Sequestration-Retrofitting Coal-Fired Power Plant
SURFACE DISSOLUTION
Modeling Surface Dissolution: Overview
• Solubility of CO2 in Brine (Aquifer & Surface)• Amount of Brine Needed• Operational and Capital Costs
Ultimate Aquifer Solubility of CO2 in 10,000ppm-120,000ppm NaCl Brine
Moles 1.5%-2.2% mole
Mass 3.7%-5.4% mass
Solubility of CO2 in Brine:
• with temperature
• with pressure
• with salinity
Modeling Surface Dissolution: Solubility in Brine in the Aquifer
0.0
0.5
1.0
1.5
2.0
2.5
0 2000 4000 6000
Aquifer Depth (ft)
10,000ppm
20,000ppm
30,000ppm
40,000ppm
60,000ppm
80,000ppm
120,000ppmSol
ubili
ty C
O2 (
mol
e %
)
Aquifer Depth (ft)
STANDARD APPROACH
BELOW 2600FT
Increasing salinity
deg0.44 1100
dP psi dT Fdz ft dz ft
Modeling Surface Dissolution: Brine Rate Comparable to Other Plant Usage
Flow rates required for Captured CO2 for Coal-Fired Power Plant
General 500MW
CO2 Emitted 8000 tonne/yr-MW
4 million tonne/yr
Brine needed for Surface Dissolution
~2,000-8,000 bbl/d-MW
1-4 million bbl/d
Typical Cooling Water for Coal-Fired Plant
Water for Once-through Cooling
14,000 bbl/d-MW
7 million bbl/d
Operational and Capital Costs for Surface Dissolution
Operational Costs• CO2 Compression
- Polytropic Compression- η=79.6%- 4 stages
• Brine compression- Incompressible- 80% efficient
Capital Costs• Injection and Extraction wells
- $750,000 per well- 35,000bbl/d-well
• CO2 Compressors and Brine Pumps- $900,000 per MW
consumed for pumping• Pressure Mixing Vessel
- ~$25,000 per MW of power plant
Costs for Surface Dissolution Approach
Costs of Surface Dissolution forCarbon Sequestration in Saline Aquifer
Process Operationala Capitalb
Capture 17% $500k-$1,000k + $400k-$900kExtract and Inject 10% + 6-9%
Monitoring Buoyancy 0% $0
Buoyant CO2 Liability 0% $0
a % of Total Power Plant Capacity b per MW of Power Plant CapacityTBD = to be determined
Surface Dissolution in Saline Aquifer:Technical Challenges
• Surface Challenges- Strong Temperature Dependence (Shallow is Better)- Strong Salinity Dependence (Shallow is Better)- Well Costs Influential (Shallow is Better)- Dissolving CO2 in short time (less than few minutes)
- Carbonic acid might cause corrosion• Subsurface Challenges
- Large Areal Target and Large Injection Volume• Can we get the brine in and out?• What if the CO2 -dense brine shows up at the
extraction wells?
Cost Comparison of Approaches
Comparison of Costs for Surface Dissolution vs. Standard Approach
Standard Surface Dissolution
Operating Costs ~28%a 33-36%a
Capital Costs $500k- $1,000kb ~$850k-$1,800kb
Liability of Buoyancy Driven Leakage TBD $0
a % of Total Power Plant Capacityb per MW of Power Plant CapacityTBD = to be determined
Double CAPEX
5-8% More OPEX
Cost Comparison of Approaches
Comparison of Costs for Surface Dissolution vs. Standard Approach
Standard Surface Dissolution
Operating Costs $28/tonne $33-$36/tonne
Capital Costs $20- $40/tonne $34-$72/tonne
Liability of Buoyancy Driven Leakage TBD $0
Totals ~$50-$70/tonne ~$70-$105/tonne
$20-$35 added / tonne
• Cheap Solution• Simple Solution• Safe Solution
Conclusion—Motivation Evaluation
?
• Pro’s - Safety Sells - No Buoyant Migration- Interaction with Seal, Faults,
Wells- Increases Aquifer Availability
• Con’s- Added Costs- Additional Fluid Handling- Added Facilities
(Compressors, Wells, etc.)- Requires More Aquifer
Space - Technical Challenges
(Carbonic Acid, Predicting Temperature, Predicting Reservoir, etc.)
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