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| Titel |
Parameter sensitivity analysis on potential fault reactivation induced by CO2 injection in a multi-layer storage formation |
| VerfasserIn |
Bruno Figueiredo, Chin-Fu Tsang, Jonny Rutqvist, Jac Bensabat, Auli Niemi |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250103317
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| Publikation (Nr.) |
 EGU/EGU2015-2725.pdf |
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| Zusammenfassung |
| Fault instability is studied in the context of the Heletz site which was chosen as a test site for scientific CO2 injection experiment in the framework of the EU-MUSTANG project. The potential reservoir for CO2 storage consists of three sandstone layers, separated by low-permeability shale layers of various thicknesses, and overlaid by a five-meter limestone and a thick impermeable shale as a caprock. A hydro-mechanical model has been developed to study the interaction between mechanical deformation and fluid flow in the storage formation bounded by two sub-vertical normal faults on either side during CO2 injection and storage. The impact caused by the pore pressure build-up on the fault reactivation, the fault slip displacement, and potential CO2 leakage through the caprock, is analyzed. Five key parameters have been identified for the hydro-mechanical model: the fault dip angle, the stress field, the offset of the layers across the faults, the fault initial permeability and the permeability of the confinement formations. A sensitivity analysis on these parameters has been conducted. It was found that results are not very sensitive to the fault dip angle. It was also found that the two faults are mechanically reactivated when (1) the ratio between the horizontal and vertical stresses is equal or smaller than 0.6, (2) the permeability of the confinement formations is smaller than 10-18 m2 and (3) the fault initial permeability is 10-18 m2. However, the impact is not significant. In the first case, the pore pressure build-up close to the faults is not enough to induce significant shear plastic strains and displacement along the faults. Results obtained in cases (2) and (3) showed that even when the total pore pressure at the storage layers is two and three times (respectively) the initial pore pressure, the maximum fault slip displacement is 1.5 cm and the maximum fault permeability is approximately only two times the initial permeability. No significant CO2 leakage through the caprock was observed in any of the cases analyzed. The offset of the layers across the faults is identified to be an important site parameter, mainly because it limits the lateral extension of the plume and hence leads to an increase in CO2 leakage through the caprock. |
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