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Thermo-mechanical Properties of Upper Jurassic (Malm) Carbonate Rock Under Drained Conditions

Pei, L. ; Blöcher, G. ; Milsch, H. ; Zimmermann, G. ; Sass, I. ; Huenges, E. :
Thermo-mechanical Properties of Upper Jurassic (Malm) Carbonate Rock Under Drained Conditions.
[Online-Edition: https://doi.org/10.1007/s00603-017-1313-0]
In: Rock Mechanics and Rock Engineering, 51 (1) S. 23-45. ISSN 1434-453X
[Artikel] , (2018)

Offizielle URL: https://doi.org/10.1007/s00603-017-1313-0

Kurzbeschreibung (Abstract)

The present study aims to quantify the thermo-mechanical properties of Neuburger Bankkalk limestone, an outcrop analog of the Upper Jurassic carbonate formation (Germany), and to provide a reference for reservoir rock deformation within future enhanced geothermal systems located in the Southern German Molasse Basin. Experiments deriving the drained bulk compressibility C were performed by cycling confining pressure p c between 2 and 50 MPa at a constant pore pressure p p of 0.5 MPa after heating the samples to defined temperatures between 30 and 90 °C. Creep strain was then measured after each loading and unloading stage, and permeability k was obtained after each creep strain measurement. The drained bulk compressibility increased with increasing temperature and decreased with increasing differential pressure p d = p c − p p showing hysteresis between the loading and unloading stages above 30 °C. The apparent values of the indirectly calculated Biot coefficient α ind containing contributions from inelastic deformation displayed the same temperature and pressure dependencies. The permeability k increased immediately after heating and the creep rates were also temperature dependent. It is inferred that the alteration of the void space caused by temperature changes leads to the variation of rock properties measured under isothermal conditions while the load cycles applied under isothermal conditions yield additional changes in pore space microstructure. The experimental results were applied to a geothermal fluid production scenario to constrain drawdown and time-dependent effects on the reservoir, overall, to provide a reference for the hydromechanical behavior of geothermal systems in carbonate, and more specifically, in Upper Jurassic lithologies.

Typ des Eintrags: Artikel
Erschienen: 2018
Autor(en): Pei, L. ; Blöcher, G. ; Milsch, H. ; Zimmermann, G. ; Sass, I. ; Huenges, E.
Titel: Thermo-mechanical Properties of Upper Jurassic (Malm) Carbonate Rock Under Drained Conditions
Sprache: Englisch
Kurzbeschreibung (Abstract):

The present study aims to quantify the thermo-mechanical properties of Neuburger Bankkalk limestone, an outcrop analog of the Upper Jurassic carbonate formation (Germany), and to provide a reference for reservoir rock deformation within future enhanced geothermal systems located in the Southern German Molasse Basin. Experiments deriving the drained bulk compressibility C were performed by cycling confining pressure p c between 2 and 50 MPa at a constant pore pressure p p of 0.5 MPa after heating the samples to defined temperatures between 30 and 90 °C. Creep strain was then measured after each loading and unloading stage, and permeability k was obtained after each creep strain measurement. The drained bulk compressibility increased with increasing temperature and decreased with increasing differential pressure p d = p c − p p showing hysteresis between the loading and unloading stages above 30 °C. The apparent values of the indirectly calculated Biot coefficient α ind containing contributions from inelastic deformation displayed the same temperature and pressure dependencies. The permeability k increased immediately after heating and the creep rates were also temperature dependent. It is inferred that the alteration of the void space caused by temperature changes leads to the variation of rock properties measured under isothermal conditions while the load cycles applied under isothermal conditions yield additional changes in pore space microstructure. The experimental results were applied to a geothermal fluid production scenario to constrain drawdown and time-dependent effects on the reservoir, overall, to provide a reference for the hydromechanical behavior of geothermal systems in carbonate, and more specifically, in Upper Jurassic lithologies.

Titel der Zeitschrift, Zeitung oder Schriftenreihe: Rock Mechanics and Rock Engineering
Band: 51
(Heft-)Nummer: 1
Verlag: Springer
Fachbereich(e)/-gebiet(e): 11 Fachbereich Material- und Geowissenschaften > Geowissenschaften > Fachgebiet Angewandte Geothermie
11 Fachbereich Material- und Geowissenschaften > Geowissenschaften
11 Fachbereich Material- und Geowissenschaften
Hinterlegungsdatum: 24 Jan 2018 06:29
DOI: 10.1007/s00603-017-1313-0
Offizielle URL: https://doi.org/10.1007/s00603-017-1313-0
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