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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
“Geological sequestration of CO2 [is] a profoundly non-feasible option for the management of CO2 emissions “
It would be hard to inject CO2 into a closed system withouteventually producing so much pressure that it fractured the rock and allowed thecarbon to migrate to other zones and possibly escape to the surface.
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
Present USA oil and gas produced 16 M bpd (oil equiv.)Present water injected USA 38 M bpd
By 2030 would require injection of 39 M bpd
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
Opportunities for CO2 Storage
around Scotlandhttp://www.geos.ed.ac.uk/sccs/regional-study/
The reservoir
Suppose an aquifer exists in the vicinity of the plant with porosity 20%, permeability 100 md, and thickness 100 ft
road
aquifers100 ft
Subsurface has MANY aquifers, thickness hundreds metres
Grand Canyon, Az Sheep Mountain anticline, Wyoming
Real world tests : 1
20 technical tests of CO2 injection to aquifers, 4 >1Mt/yr
Real world : 2.1Pressure measured at top of borehole (and) at base
wellhead
sandface
Real World : 2.2
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
Sleipner “significant leakage to overlying layers.”
Real world tests : 3
temperature
pressure
Pressure builds rapidly to managed plateauAfter cessation, pressure falls rapidly ==> open system
Bass Islands Dolomite in the Michigan Basin, 10241t
Real world test : 4
FAILURE: pressure buildup, and no declinePorosity 3.2% Permeability 0.001 - 0.08mD, Thickness 20m
pressure
Simulation of injection
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2 inj and 2 prod , 100 ft thickness, area 854 sq miles
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Static volume Dynamic volume Dynamic volume + engineering
Eric Mackay (Heriot-Watt)
Simulation with water production
?
• Economides = 1155 injection wells needed
• Use enhanced voidage wells = 2 injectors and 2 voidage wells
3 Mt/yr CO2, 30 years injection
Material balance is standard technique.
Producing water can create extra storage space
need for hundreds of wells
Mt
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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
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
Papers here:http://www.geos.ed.ac.uk/sccs/bumblebee.html
http://www.sciencedaily.com/releases/2010/12/101213111447.htm
Jan 2015...
https://www.sciencenews.org/article/pumping-carbon-dioxide-deep-underground-may-trigger-earthquakes
“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
• Seismic event of ML > 3.4• 3 aftershocks ML> 3• Project suspended• Public support of geothermal energy
decreased dramatically
(Swiss Seismological Service)
Rangely Weber (Colorodo, USA)
Google Maps
1901-33 oil discovered
1957/8 water flooding
1963 - 1973 19 earthquakes >2.5 magnitude
1972 injection pressures reduced!
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/blog-posts/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 unitsLi, Mg, Ca, Rb, Sr > 30 % higher in controlMn, 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 ReadingEhlig-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.