Geologic Sequestration: the Big Picture Estimation of Storage Capacity or How Big is Big Enough Susan Hovorka, Srivatsan Lakshminarasimhan, JP Nicot Gulf Coast Carbon Center Bureau of Economic Geology Jackson School of Geosciences The University of Texas at Austin Presented to TXU Carbon Management Pr IAP for CO2 Capture by Aqueous Absorption Semi-annual meet Pittsburg, May 7,
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Geologic Sequestration: the Big Picture Estimation of Storage Capacity or How Big is Big Enough
Geologic Sequestration: the Big Picture Estimation of Storage Capacity or How Big is Big Enough. Susan Hovorka, Srivatsan Lakshminarasimhan, JP Nicot Gulf Coast Carbon Center Bureau of Economic Geology Jackson School of Geosciences The University of Texas at Austin. - PowerPoint PPT Presentation
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Geologic Sequestration: the Big Picture
Estimation of Storage Capacity or How Big is Big Enough
Susan Hovorka, Srivatsan Lakshminarasimhan, JP NicotGulf Coast Carbon Center
Bureau of Economic GeologyJackson School of GeosciencesThe University of Texas at Austin
Presented to TXU Carbon Management ProgramIAP for CO2 Capture by Aqueous Absorption Semi-annual meeting,
Pittsburg, May 7, 2007
Large Volumes in the Subsurface NETL National Atlas Estimate
Kh= Horizontal permeability Kh = vertical permeability. Related to rock fabric,Interpreted from sedimentary depositional environment
Options for Estimating Capacity
• Volumetric approach: Total pore volume x Efficiency factor (E)– Free CO2 volume in structural and stratigraphic traps– Trapped CO2 residual phase
• Volume dissolved• Volume that can be stored beneath an area
constrained by surface uses or by other unacceptable risks – well fields, faults
• Pressure limits as a limit on capacity• Displaced water as a limit on capacity
Nearly Closed Volume – Maximum Capacity May be Pressure Determined
Injection Pressure and Depth
• Maximum injection pressure must be less than fracture pressure
• Fracture pressure estimated to linearly increase with depth of formation
• Volume injected below fracture pressure increases with depth
Maximum CO2 injected (Vi) for Given Pore Volume (Vp)
• Closed domain at several porosities and several different sizes leading to a range of brine-filed volumes Homogeneous geological formation, dimensions 10,000 ft x 10,000 ft x 1000 ft, and permeability 10 md, depth 7000 ft. Maximum pressure set at 75% lithostatic.
10% porosity
20% porosity
30% porosity
Effect of Depth of formation
• Effect of the depth of formation almost entirely due to that of injection pressure
Effect of pore volume (contd)
• Best fit over entire data suggest linear (blue) scaling • Ratio of injected to pore volume is about 1.5 %
Vi = 0.01481 Vp
Options for Estimating Capacity
• Volumetric approach: Total pore volume x Efficiency factor (E)– Free CO2 volume in structural and stratigraphic traps– Trapped CO2 residual phase
• Volume dissolved• Volume that can be stored beneath an area
constrained by surface uses or by other unacceptable risks – well fields, faults
• Pressure limits as a limit on capacity• Displaced water as a limit on capacity
Open Hydrologic System
Fluid Displacement From an Open Hydrologic System
0
100
200
300
400
500
600
700
800
0 250 500 750 1000
Time from Start of Injection (years)
To
tal W
ate
r F
lux
(M
m3 /y
r)
0
100
200
300
400
500
Inje
cti
on
Ra
te (
Mt
CO
2/y
r)
Injection rate
Total water flux at 30 km
Total water flux at 100 km
Output of an analytical model. Total means across the boundaries Vb1 and Vb2. Note: vertical axes are approximately equivalent (500 tons of CO2 is 500 t / 0.6 t/ m3 = 833 m3 of displaced water)
Carrizo-Wilcox System in Central Texas
From Dutton et al., 2003
SENW
Lee Co. Fayette Co. Colorado Co.
Youngerformat ions
Older formations
Base of potable water
Topgeopressured
zone
Faults
Faults
Ground surface
Carrizo
0
-2,000
-4,000
-6,000
-8,000
-10,000
-12,000
-14,000 Vertica l scale greatly exaggerated
0
0
40 mi
40 km
Calvert Bluff
Simsboro
Hooper
College StationWell Field
CO2 Injection
Fate of a Pressure Pulse in a Confined Aquifer
0
50
100
150
200
250
300
350
400
450
500
2000 2010 2020 2030 2040 2050
Calendat Year
Pro
du
ced
/In
ject
ed V
olu
me
(mil
lio
n m
3)
All Pumping
Pumping from Simsboro (L5)
CO2 Injection
Year 2000heads
Year 2050heads
Conclusions• Volumetric approach: DOE assessment shows
more than adequate space– Free CO2 volume in structural and stratigraphic traps– Trapped CO2 residual phase
• Volume dissolved – Significance and rate uncertain
• Volume that can be stored beneath an area constrained by surface uses or by other unacceptable risks - What are key risks?
• Pressure limits as a limit on capacity – Similar volume to that used in volumetric approach 1.5 % of pore volume useful, increases with depth
• Displaced water as a limit on capacity – minor in large basins