date: 2021-10-29T01:23:40Z
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pdf:docinfo:title: Long-Term Evolution of Fracture Permeability in Slate: An Experimental Study with Implications for Enhanced Geothermal Systems (EGS)
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Keywords: fracture; permeability; fluid?rock interactions; slate; temperature; time-dependent; pressure solution; dissolution
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subject: The long-term sustainability of fractures within rocks determines whether it is reasonable to utilize such formations as potential EGS reservoirs. Representative for reservoirs in Variscan metamorphic rocks, three long-term (one month each) fracture permeability experiments on saw-cut slate core samples from the Hahnenklee well (Harz Mountains, Germany) were performed. The purpose was to investigate fracture permeability evolution at temperatures up to 90 C using both deionized water (DI) and a 0.5 M NaCl solution as the pore fluid. Flow with DI resulted in a fracture permeability decline that is more pronounced at 90 C, but permeability slightly increased with the NaCl fluid. Microstructural observations and analyses of the effluent composition suggest that fracture permeability evolution is governed by an interplay of free-face dissolution and pressure solution. It is concluded that newly introduced fractures may be subject to a certain permeability reduction due to pressure solution that is unlikely to be mitigated. However, long-term fracture permeability may be sustainable or even increase by free-face dissolution when the injection fluid possesses a certain (NaCl) salinity.
dc:creator: Chaojie Cheng, Johannes Herrmann, Bianca Wagner, Bernd Leiss, Jessica A. Stammeier, Erik Rybacki and Harald Milsch
dcterms:created: 2021-10-29T01:18:25Z
Last-Modified: 2021-10-29T01:23:40Z
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title: Long-Term Evolution of Fracture Permeability in Slate: An Experimental Study with Implications for Enhanced Geothermal Systems (EGS)
Last-Save-Date: 2021-10-29T01:23:40Z
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pdf:docinfo:keywords: fracture; permeability; fluid?rock interactions; slate; temperature; time-dependent; pressure solution; dissolution
pdf:docinfo:modified: 2021-10-29T01:23:40Z
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dc:title: Long-Term Evolution of Fracture Permeability in Slate: An Experimental Study with Implications for Enhanced Geothermal Systems (EGS)
modified: 2021-10-29T01:23:40Z
cp:subject: The long-term sustainability of fractures within rocks determines whether it is reasonable to utilize such formations as potential EGS reservoirs. Representative for reservoirs in Variscan metamorphic rocks, three long-term (one month each) fracture permeability experiments on saw-cut slate core samples from the Hahnenklee well (Harz Mountains, Germany) were performed. The purpose was to investigate fracture permeability evolution at temperatures up to 90 C using both deionized water (DI) and a 0.5 M NaCl solution as the pore fluid. Flow with DI resulted in a fracture permeability decline that is more pronounced at 90 C, but permeability slightly increased with the NaCl fluid. Microstructural observations and analyses of the effluent composition suggest that fracture permeability evolution is governed by an interplay of free-face dissolution and pressure solution. It is concluded that newly introduced fractures may be subject to a certain permeability reduction due to pressure solution that is unlikely to be mitigated. However, long-term fracture permeability may be sustainable or even increase by free-face dissolution when the injection fluid possesses a certain (NaCl) salinity.
pdf:docinfo:subject: The long-term sustainability of fractures within rocks determines whether it is reasonable to utilize such formations as potential EGS reservoirs. Representative for reservoirs in Variscan metamorphic rocks, three long-term (one month each) fracture permeability experiments on saw-cut slate core samples from the Hahnenklee well (Harz Mountains, Germany) were performed. The purpose was to investigate fracture permeability evolution at temperatures up to 90 C using both deionized water (DI) and a 0.5 M NaCl solution as the pore fluid. Flow with DI resulted in a fracture permeability decline that is more pronounced at 90 C, but permeability slightly increased with the NaCl fluid. Microstructural observations and analyses of the effluent composition suggest that fracture permeability evolution is governed by an interplay of free-face dissolution and pressure solution. It is concluded that newly introduced fractures may be subject to a certain permeability reduction due to pressure solution that is unlikely to be mitigated. However, long-term fracture permeability may be sustainable or even increase by free-face dissolution when the injection fluid possesses a certain (NaCl) salinity.
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pdf:docinfo:creator: Chaojie Cheng, Johannes Herrmann, Bianca Wagner, Bernd Leiss, Jessica A. Stammeier, Erik Rybacki and Harald Milsch
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creator: Chaojie Cheng, Johannes Herrmann, Bianca Wagner, Bernd Leiss, Jessica A. Stammeier, Erik Rybacki and Harald Milsch
meta:author: Chaojie Cheng, Johannes Herrmann, Bianca Wagner, Bernd Leiss, Jessica A. Stammeier, Erik Rybacki and Harald Milsch
dc:subject: fracture; permeability; fluid?rock interactions; slate; temperature; time-dependent; pressure solution; dissolution
meta:creation-date: 2021-10-29T01:18:25Z
created: Fri Oct 29 03:18:25 CEST 2021
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meta:keyword: fracture; permeability; fluid?rock interactions; slate; temperature; time-dependent; pressure solution; dissolution
Author: Chaojie Cheng, Johannes Herrmann, Bianca Wagner, Bernd Leiss, Jessica A. Stammeier, Erik Rybacki and Harald Milsch
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