Geothermal fluid extraction and injection-related fracture slip susceptibility and seismicity in naturally fractured rocks
File(s)
Published version
Author(s)
Type
Journal Article
Abstract
Understanding fracture slip susceptibility in geothermal reservoirs is central to the control of fluid injection-induced seismicity. To investigate the role of regional fracture systems on induced seismicity, a coupled thermo-hydro-mechanical (THM) model containing fracture networks was developed, which features direct coupling between different physics for explicit fractures, fractured rocks (porous matrix blocks with small-scale fractures) and their interactions, as well as indirect coupling through changes of material properties, such as stress-dependent fracture and rock permeabilities. The model was applied to simulate geothermal fluid extraction and re-injection in a natural fracture system comprised of three dominant fracture sets at the Hellisheiði geothermal field over a 10-year period (2011–2021), utilising field recorded monthly production and re-injection rates. Based on the model results, the slip susceptibility of regional fracture systems was examined under reservoir conditions before and after the start of fluid re-injection across different time scales, i.e., over short (1 month), intermediate (1 year) and long-term (10 years). Two model scenarios, one with cooling contraction and one without, were considered to examine the relative contribution of cooling contraction and fluid overpressure on fracture slip susceptibility. Results have shown that fracture networks act as preferential fluid flow paths that influence fluid pressure and stress distribution and fracture slip susceptibility in geothermal reservoirs. NE-SW and N-S trending fractures at Hellisheiði are susceptible to slippage before the start of fluid re-injection. During fluid re-injection, the distribution of fractures with enhanced slip susceptibility gradually shifts from surrounding the re-injection region to forming a two-lobed pattern in the fault-normal direction around the re-injection region, indicating the dominant role of cooling contraction over fluid overpressure on the fracture slip susceptibility in the intermediate- and long-term.
Date Issued
2024-11-01
Date Acceptance
2024-10-12
Citation
International Journal of Rock Mechanics and Mining Sciences, 2024, 183
ISSN
1365-1609
Publisher
Elsevier
Journal / Book Title
International Journal of Rock Mechanics and Mining Sciences
Volume
183
Copyright Statement
© 2024 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC license (http://creativecommons.org/licenses/by-nc/4.0/).
License URL
Subjects
Cooling contraction
DEFORMATION
EARTHQUAKE
Engineering
Engineering, Geological
FAULT
FIELD
Fluid overpressure
Fracture system
Geothermal exploitation
HEAT-TRANSFER
Induced seismicity
Mining & Mineral Processing
MODEL
OKLAHOMA
PERMEABILITY
Physical Sciences
Science & Technology
Technology
Thermo-hydro-mechanical coupling
WATER INJECTION
Publication Status
Published
Article Number
105939
Date Publish Online
2024-10-28