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.)