Current Issues in Geological Storage
Mark Wilkinson, University of Edinburgh
Pressure build-up and injection rates
Climate change skeptics. Pro fossil-fuel, with a no-CCS agenda.
A disproportionate effect on public uncertainty
http://www.guardian.co.uk/business/2010/apr/25/research-viabilty-carbon-capture-storage
Economides’ propositions
For moderate size reservoirs, still the size of Alaska’s
Prudhoe Bay reservoir, and with moderate permeability
there would be a need for hundreds of wells
It would be hard to inject CO2 into a closed system
without eventually producing so much pressure that it
fractured the rock and allowed the carbon to migrate to
other zones and possibly escape to the surface.
“Geological sequestration of CO2 [is] a profoundly nonfeasible option for the management of CO2 emissions “
By 2030 would require injection of 39 M bpd
Present USA oil and gas produced 16 M bpd (oil equiv.)
Present water injected USA 38 M bpd
Opportunities for
CO2 Storage
around Scotland
http://www.geos.ed.ac.uk/
sccs/regional-study/
Economides said:
Too much pressure causes
fractures (true !)
Limited to only 1 % of water
volume (probably true !)
Scottish Study: 0.2 - 2 %
= 4 – 46 Gt CO2 storage
Suppose an aquifer exists in the vicinity of the plant with
porosity 20%, permeability 100 md, and thickness 100 ft
The reservoir
Grand Canyon, Az
Sheep Mountain anticline, Wyoming
Subsurface has MANY aquifers, thickness hundreds metres
Real world tests : 1
20 technical tests of CO2 injection to aquifers, 4 >1Mt/yr
Real world : 2.1
wellhead
Pressure measured at top
of borehole (and) at base
sandface
Real World : 2.2
Sleipner “significant leakage
to overlying layers.”
Utsira Sand has an estimated pore-space volume of about 6 x
1011 m3. If only 1% of this were utilised for CO2 storage, that
stores 50 years emissions from around 20 coal-fired plant
Bass Islands Dolomite in the Michigan Basin, 10241t
Real
world tests : 3
pressure
Pressure builds rapidly to managed plateau
After cessation, pressure falls rapidly ==> open system
Real world test : 4
FAILURE: pressure buildup, and no decline
Porosity 3.2% Permeability 0.001 - 0.08mD, Thickness 20m
2 inj and 2 prod , 100 ft thickness, area 854 sq miles
change in reservoir pressure at one injector (psi)
need for hundreds of
wells
Simulation of injection
1800
1600
1400
• Economides = 1155
injection wells needed
• Use enhanced voidage
wells = 2 injectors and 2
voidage wells
1200
1000
3 Mt/yr CO2, 30
years injection
800
600
400
200
700
0
0
5
10
15
600
time (years)
Simulation with water production
20
25
30
500
Material balance
is standard
technique.
Producing water
can create extra
storage space
400
?
300
200
100
0
Static volume
Eric Mackay (Heriot-Watt)
Dynamic volume
Dynamic volume +
engineering
Economides’ model is correct in its own terms.
BUT makes unreasonable assumptions ==> wrong result
1) Modelling shows large
pressure increase –
‘only’ 1 % of space
useable
2) Over-estimation of CO2
storage capacity
3) One power plant =
‘small US State’ area
4) Many wells needed for
1 powerplant
Papers here:
http://www.geos.ed.ac.uk/sccs/bumblebee.html
1) CO2 storage 0.2 – 2 %
efficient previously!
2) Faulty use of one 30m
reservoir; 10x too thin
3) Injection evidence from
world tests show Mt
injection
4) Use ‘horizontal’ wells to
reduce near-borehole
pressure
5) If needed: Pressure
management by water
production
http://www.sciencedaily.com/releases/2010/12/101213111447.htm
https://www.sciencenews.org/article/pumping-carbon-dioxide-deep-underground-may-trigger-earthquakes
Jan 2015...
“We have faults that are accumulating stress over thousands to hundreds
of thousands of years, even in Iowa,” says Stanford University
geophysicist Mark Zoback. “So when you inject water or gas or any fluid
it can set some of them off.”
Shale gas waste water injection in USA
https://www.sciencenews.org/article/pumping-carbon-dioxide-deep-underground-may-trigger-earthquakes
Deep Heat Mining Project, Basel
2006
(Swiss Seismological Service)
•
•
•
•
Seismic event of ML > 3.4
3 aftershocks ML> 3
Project suspended
Public support of geothermal energy
decreased dramatically
Rangely Weber
(Colorodo, USA)
1901-33 oil discovered
1957/8 water flooding
1963 - 1973 19 earthquakes >2.5
magnitude
1972 injection pressures reduced!
Google Maps
Injected volume controls max magnitude?
IEAGHG Induced seismicity
and its implications for CO2
storage risk, 2013, report
2013/09
Graphs are biased data sets,
omits all fields (>95 %?) with
no reported quakes
“The risks associated with
induced seismicity at CCS
sites can be reduced and
mitigated using a systematic
and structured risk
management programme.”
Earthquake issues:
•
Similar, or less, than coalmining areas
•
People there are happy if they are getting paid!
•
UK or Scotland = offshore, where seismic activity routinely occurs, and
nobody notices.
•
Small earthquakes do not mean rupture of the seal
•
Small earthquakes mean small displacement, and small displacement does not
imply a leak of fluid.
•
At shallower depths seals are less cemented, so far more flexible and smear
along or fracture plane during displacement, consequently self sealing.
•
So, a moderate to large deal if you are trying to store on shore. But not a very
big deal at all if you are storing offshore.
•
More positive: http://www.iea-coal.org.uk/site/2010/blog-section/blogposts/ccs-and-earthquakes-not-as-likely-as-some-may-suggest
•
http://www.abc.net.au/science/articles/2012/06/19/3527827.htm
Aquifer contamination by CO2
What did they do?
•
•
•
•
Take disaggregated samples of aquifer rock
Put in CO2-rich water for > 300 days
Analyse water periodically
Control was same rock in water without CO2
stream
What happened?
pH dropped by 1 -1.5 units
Li, Mg, Ca, Rb, Sr > 30 % higher in control
Mn, Fe, Co, Ni, Zn 1000% higher
Gilfillan & Haszeldine reply:
• Massively too high CO2 quantity (“small leak”??)
• Aquifers had natural high trace element concentrations
• Sediments disaggregated, hence higher reactive area
• Controls not valid (agitated?)
• Experiments oxidising, real aquifers reducing
• Some ‘misleading’ statements
e.g. “Mn, Fe, Co, Ni, Zn 1000%
higher” actually lower
than natural waters!
More reply:
• Data quality: odd spike at
300 days
• Concentrations decrease,
so at least some effects
temporary, i.e.
experimental artifact?
• Last – natural CO2-rich
waters drunk safely!
Experimental studies now common:
Varadharajana, C. et al., 2013, A laboratory study of the initial effects of dissolved carbon dioxide
(CO2) on metal release from shallow sediments. International Journal of Greenhouse Gas Control,
v.19, p.183–211
Cahill, A.G. et al., 2013, Risks attributable to water quality changes in shallow potable aquifers
from geological carbon sequestration leakage into sediments of variable carbonate content
International Journal of Greenhouse Gas Control, v. 19, p. 117–125
References and Further Reading
Ehlig-Economides, C. & Economides, M.J., 2010, Sequestering carbon dioxide in a closed underground volume.
Journal of Petroleum Science & Engineering, v.70, p.123-130. http://dx.doi.org/10.1016/j.petrol.2009.11.002
Klusman, R.W., 2003, A geochemical perspective and assessment of leakage potential for a mature carbon
dioxide–enhanced oil recovery project and as a prototype for carbon dioxide sequestration; Rangely field,
Colorado. AAPG Bulletin; September 2003; v. 87; no. 9; p. 1485-1507.
Gilfillan, S. M. V.; Haszeldine, R. S. Comment on “Potential impacts of leakage from deep CO2
geosequestration on overlying freshwater aquifers”. Environmental Science & Technology, 44, 9225 – 9232.
201110.1021/es104307h.
Hunt, J.M., 1995, Petroleum Geochemistry and Geology, 2nd Edition, Freeman.
Little, M. G.; Jackson, R. B., 2010, Potential Impacts of Leakage from deep CO2 Geosequestration on Overlying
Freshwater Aquifers. Environ. Sci. Technol. 44, 9225 – 9232
Little, M. G.; Jackson, R. B. Response to comment on “Potential impacts of leakage from deep CO2
geosequestration on overlying freshwater aquifers”. Issues Sci. Technol.