 |
| Titel |
The impact of geological storage of CO2 on the mechanical behaviour of faults - Can we predict frictional strength and stability? |
| VerfasserIn |
Elisenda Bakker, Suzanne J. T. Hangx, Christopher J. Spiers |
| Konferenz |
EGU General Assembly 2013
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250082922
|
|
|
|
|
|
| Zusammenfassung |
| CO2 storage in depleted oil and gas reservoirs is seen as an important climate change
mitigation strategy. In order to evaluate storage integrity of the reservoir-caprock system,
potential leakage pathways, such as pre-existing or induced faults, need to be investigated.
The mechanical and transport properties of intact and fractured rock may be affected by both
short and long-term (> 100 years) fluid-rock interactions. In practice, chemical interactions
that occur on timescales longer than a few months are too slow and difficult to reproduce in
laboratory experiments.
Recently, research within the CCS community has steered towards investigating the effect
of CO2 on fault stability and particularly towards induced seismicity. In this context, we
performed a variety of mechanical tests on rock types relevant for CCS sites, with the aim of
investigating the effect of CO2/brine/rock interactions on the mechanical and transport
properties of faults. To this end, we used both CO2-exposed and unaltered rocks obtained
from sandstone reservoirs of natural CO2 fields located at Green River (Utah, USA) and
Werkendam (The Netherlands). Two main types of experiment were performed: 1) triaxial
tests in which cylindrical samples were shear fractured, studying subsequent slip on the fault,
and 2) direct shear tests performed on (simulated) fault gouge prepared by crushing intact
rock.
Our results showed that the frictional stability of fault gouges is largely controlled by
factors such as mineralogical composition, notably carbonate content, and temperature. We
have placed our results in the context of the large body of data that already exists on fault
gouge friction behaviour. The combined body of work encompasses materials ranging from
clay-quartz mixtures, to anhydrite and carbonate rocks, all of which are relevant rock types
for CCS. In this way, we delineate the knowledge gaps that still exist, and we show how
the available data can be used to make preliminary predictions on fault friction
behaviour and (micro)seismic fault reactivation potential in geological CO2-storage
systems. |
|
|
|
|
|
|