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| Titel |
The influence of carbon-dioxide on the strength and stability of CO2-sequestration reservoir fault zones |
| VerfasserIn |
Jon Samuelson, Chris Spiers |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250056114
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| Zusammenfassung |
| Rising levels of CO2 in the Earth’s atmosphere appear to be to be resulting in a greenhouse
effect that is causing the global mean temperature to rise beyond what it would be without
anthropogenic forcing. Human emissions of CO2 to the atmosphere have been increasing
since the beginning of the industrial revolution, drastically so beginning in the late 1940’s,
and continuing to rise today. Since 1940 worldwide carbon emissions have increased from
about 1.3-billion tonnes per year to the present levels in excess of 8-billion tonnes per
year, leading to an increase of atmospheric CO2 concentration of approximately
30
Of the many methods of mitigating human induced impact on the global climate,
including increased use of nuclear, wind, geothermal, and hydrogen based energy sources;
electric and more fuel efficient vehicles; reforestation; and improved agricultural techniques,
one of the most immediately practical solutions is Carbon Capture and Storage (CCS). CCS
involves the capture of CO2 at large point sources, such as ammonia and cement
manufacturing plants and coal burning power plants, followed by injection and storage in
depleted oil and gas reservoirs and/or deep saline aquifers.
The risks associated with CO2 sequestration lead to a great deal of concern
on the part of the public-at-large, which must be mitigated if CCS projects are to
become a truly acceptable solution to human influence on the Earth’s climate. The
basic concerns of the public with regard to CCS are “Will the CO2 stay where we
put it?” and “What dangers are associated with putting it down there?” We aim to
address the latter of these concerns, specifically in regards to measuring the frictional
strength and stability of caprock derived fault gouge and the influence of long term
CO2 reaction on these same properties, as many potential reservoirs are bounded
laterally by relatively impermeable fault zones. It has long been understood that
changing the state of stress in a reservoir by altering the pore pressure through
extraction or injection of fluids (oil, water, CO2, etc.) can result in reactivation
of fault zones in the reservoir and caprock, potentially resulting in earthquakes.
In the case of CO2 sequestration, not only is the changing fluid pressure of the
reservoir an important factor in the reactivation of fault zones, but also the potential
for long term alteration of the strength and stability of the bounding and interior
faults. By conducting direct shear experimental analyses at reservoir temperature
and pressure conditions (Â 35 MPa and 115 °C) we seek to answer the following
questions: What are the frictional strength and stability properties of fault gouge in
a real world potential sequestration reservoir? What mineralogical changes will
long term reaction with supercritical CO2 impart upon caprock fault gouge? Will
these changes alter the strength and stability of fault zones in the sequestration
area? |
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