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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Eric Mackay (Heriot-Watt)

Simulation with water production

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• 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

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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.