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| Titel |
The effect of temperature on mechanical and hydraulic properties of Flechtinger sandstone |
| VerfasserIn |
A. Hassanzadegan, G. Bloecher, H. Milsch, G. Zimmermann |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250059050
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| Zusammenfassung |
| This research addresses the temperature dependence of static and dynamic elastic moduli and
transport properties of Flechtinger sandstone at drained conditions. Static moduli were
determined by stress-strain curves in a conventional triaxial test. Dynamic elastic moduli
were derived from acoustic wave velocities. Flechtinger is an outcropping equivalent of north
German basin reservoir rock (Rotliegend sandstone). The pore pressure was maintained
constant at 1 MPa, confining pressure was cycled between 2 to 55 MPa and temperature
increased step wise. The permeability of the Flechtinger sandstone at different temperatures
was determined while keeping the downstream at a constant pressure of 1 MPa an applying
constant flow rate.
The hydraulic (porosity, permeability) and poroelastic properties (drained bulk modulus,
storage coefficient) were derived by employing drained poroleasticity theory and Darcy’s law.
The stress strain curves showed nonlinear behavior. Two types of nonlinearity in
mechanical behavior of granular rock were distinguished in this study, one due to
Hertizan contacts and crack closure and the other due to the temperature and stress
dependence of physical properties. The drained bulk modulus showed pressure and
temperature dependence. Applying pressure always increased the drained bulk
modulus of Flechtinger sandstone. In contrast, the effect of temperature was pressure
dependent. Both compressional and shear wave velocity increased by increasing
pressure and temperature. The compressional wave velocity was increasing 31% with
increasing effective pressure from 1 to 54 MPa. Moreover, it was raised 3.5% with
increasing temperature from 25Ë C to 140Ë C. The interrelation between thermal
expansion coefficient and bulk modulus, and the path dependence of heat transfer
processes govern the temperature effect on granular rock and changes in pore geometry. |
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