Effects of geomechanical changes on the validity of a discrete fracture network representation of a realistic two-dimensional fractured rock
File(s)AFNDFN_Revised.docx (5.85 MB)
Accepted version
Author(s)
Type
Journal Article
Abstract
This paper aims to examine the validity of the discrete fracture network (DFN) method in representing a realistic two-dimensional fractured rock in terms of their geomechanical response to in-situ stresses and hydraulic behaviour in a steady state fluid field. First, a real fracture network is extracted from the geological map of an actual rock outcrop, which is termed the analogue fracture network (AFN). Multiple DFN realisations are created using the statistics of the analogue pattern. A conductivity parameter that was found to have a linear relationship with the conductivity of 2D fracture networks is included to further enhance network similarity. A series of numerical experiments are designed with far-field stresses applied at a range of angles to the rock domains and their geomechanical response is modelled using the combined finite-discrete element method (FEMDEM). A geomechanical comparison between the AFN and its DFN equivalents is made based on phenomena such as heterogeneity of fracture-dependent stress contours, sliding between pre-existing fracture walls, coalescence of propagating fractures and variability of aperture distribution. Furthermore, an indirect hydro-mechanical (HM) coupling is applied and the hydraulic behaviour of the porous rock models is investigated using the hybrid finite element-finite volume method (FEFVM). A further comparison is conducted focusing on the hydraulic behaviour of the AFN and DFNs under the effects of geomechanical changes. The results show that although DFNs may represent an AFN quite well for fixed mechanical conditions, such a representation may not be dependable if mechanical changes occur.
Date Issued
2014-09-01
Date Acceptance
2014-06-12
Citation
International Journal of Rock Mechanics and Mining Sciences, 2014, 70 (1), pp.507-523
ISSN
0020-7624
Publisher
Elsevier
Start Page
507
End Page
523
Journal / Book Title
International Journal of Rock Mechanics and Mining Sciences
Volume
70
Issue
1
Copyright Statement
© 2014 Elsevier Ltd. All rights reserved. NOTICE: this is the author’s version of a work that was accepted for publication in International Journal of Rock Mechanics and Mining Sciences . Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES, Vol.: 70, (2014) DOI: 10.1016/j.ijrmms.2014.06.001
Sponsor
Engineering & Physical Science Research Council (EPSRC)
Identifier
https://www.sciencedirect.com/science/article/pii/S1365160914001439
Grant Number
GR/S42699/01
Subjects
Science & Technology
Technology
Physical Sciences
Engineering, Geological
Mining & Mineral Processing
Engineering
Fracture network
Geomechanical response
Hydro-mechanical coupling
Permeability
STRESS-DEPENDENT PERMEABILITY
FINITE-ELEMENT
TRACE LENGTH
NUMERICAL-SIMULATION
FLOW
MASSES
DEFORMATION
APERTURE
MODELS
JOINTS
Mining & Metallurgy
0905 Civil Engineering
0914 Resources Engineering and Extractive Metallurgy
Publication Status
Published
Date Publish Online
2014-07-15