Injection-driven fracture instability in granite : mechanism and implications

An unprecedented increase in earthquakes associated with hydraulic stimulation has been recognized as a major barrier to the development of enhanced geothermal systems. However, the mechanism of injection-induced seismicity remains enigmatic. Here we simulate the critical stress states of sawcut and...

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Main Authors: Ji, Yinlin, Wu, Wei
Other Authors: School of Civil and Environmental Engineering
Format: Article
Language:English
Published: 2021
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Online Access:https://hdl.handle.net/10356/154103
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Institution: Nanyang Technological University
Language: English
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spelling sg-ntu-dr.10356-1541032021-12-14T08:43:48Z Injection-driven fracture instability in granite : mechanism and implications Ji, Yinlin Wu, Wei School of Civil and Environmental Engineering Engineering::Civil engineering Injection-Induced Seismicity Laboratory Experiments An unprecedented increase in earthquakes associated with hydraulic stimulation has been recognized as a major barrier to the development of enhanced geothermal systems. However, the mechanism of injection-induced seismicity remains enigmatic. Here we simulate the critical stress states of sawcut and natural fractures, and examine the fracture instabilities due to fluid injection. We shed light on fluid pressure heterogeneity, injection-induced fracture instability, acoustic emission characteristics and fracture surface evolution. We find that injection-induced fracture instability is strongly dependent on fluid pressure heterogeneity and fracture surface heterogeneity. High injection rates can induce a high fluid overpressure ratio in the sawcut fracture, promoting the rupture of fracture extending into the unpressurized area. The instability of the natural fracture is due to the near-uniform reduction in effective normal stress associated with a low fluid overpressure ratio. Our data indicate that maintaining a low fluid overpressure ratio during injection activities could confine the rupture of fracture within the pressurized area. A turning point of the total moment release may be used as a reference to optimize the fluid injection strategy. The seismic response of rock fracture could be modified by changing fluid pathways between the injection borehole and the fracture and by evolving surface roughness of the fracture within the stimulated volume. Nanyang Technological University Wei Wu gratefully acknowledges the support of Start-up Grant from Nanyang Technological University, Singapore. 2021-12-14T08:43:47Z 2021-12-14T08:43:47Z 2020 Journal Article Ji, Y. & Wu, W. (2020). Injection-driven fracture instability in granite : mechanism and implications. Tectonophysics, 791, 228572-. https://dx.doi.org/10.1016/j.tecto.2020.228572 0040-1951 https://hdl.handle.net/10356/154103 10.1016/j.tecto.2020.228572 2-s2.0-85088913943 791 228572 en Tectonophysics © 2020 Elsevier B.V. All rights reserved.
institution Nanyang Technological University
building NTU Library
continent Asia
country Singapore
Singapore
content_provider NTU Library
collection DR-NTU
language English
topic Engineering::Civil engineering
Injection-Induced Seismicity
Laboratory Experiments
spellingShingle Engineering::Civil engineering
Injection-Induced Seismicity
Laboratory Experiments
Ji, Yinlin
Wu, Wei
Injection-driven fracture instability in granite : mechanism and implications
description An unprecedented increase in earthquakes associated with hydraulic stimulation has been recognized as a major barrier to the development of enhanced geothermal systems. However, the mechanism of injection-induced seismicity remains enigmatic. Here we simulate the critical stress states of sawcut and natural fractures, and examine the fracture instabilities due to fluid injection. We shed light on fluid pressure heterogeneity, injection-induced fracture instability, acoustic emission characteristics and fracture surface evolution. We find that injection-induced fracture instability is strongly dependent on fluid pressure heterogeneity and fracture surface heterogeneity. High injection rates can induce a high fluid overpressure ratio in the sawcut fracture, promoting the rupture of fracture extending into the unpressurized area. The instability of the natural fracture is due to the near-uniform reduction in effective normal stress associated with a low fluid overpressure ratio. Our data indicate that maintaining a low fluid overpressure ratio during injection activities could confine the rupture of fracture within the pressurized area. A turning point of the total moment release may be used as a reference to optimize the fluid injection strategy. The seismic response of rock fracture could be modified by changing fluid pathways between the injection borehole and the fracture and by evolving surface roughness of the fracture within the stimulated volume.
author2 School of Civil and Environmental Engineering
author_facet School of Civil and Environmental Engineering
Ji, Yinlin
Wu, Wei
format Article
author Ji, Yinlin
Wu, Wei
author_sort Ji, Yinlin
title Injection-driven fracture instability in granite : mechanism and implications
title_short Injection-driven fracture instability in granite : mechanism and implications
title_full Injection-driven fracture instability in granite : mechanism and implications
title_fullStr Injection-driven fracture instability in granite : mechanism and implications
title_full_unstemmed Injection-driven fracture instability in granite : mechanism and implications
title_sort injection-driven fracture instability in granite : mechanism and implications
publishDate 2021
url https://hdl.handle.net/10356/154103
_version_ 1720447195326447616