GEOTHERMAL TECHNOLOGIES LEGACY COLLECTION - Bibliographic Citation


Bibliographic Citation


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Title: Simulated evolution of fractures and fracture networks subject to thermal cooling: A coupled discrete element and heat conduction model
Creator/Author: Huang, Hai ; Plummer, Mitchell ; Podgorney, Robert
Publication Date:2013 Feb 01
OSTI Identifier:OSTI 1072397
Report Number(s):INL/CON-12-27584
DOE Contract Number:DE-AC07-05ID14517
Document Type:Conference
Specific Type:
Coverage:
Resource Relation:Conference: Stanford Geothermal Workshop,Palo Alto, CA,02/11/2013,02/13/2013
Other Number(s):
Research Org:Idaho National Laboratory (INL)
Sponsoring Org:DOE - EE
Subject:15 GEOTHERMAL ENERGY
Keywords:fracture propagation; geothermal stimulation simulation; rock deformation
Description/Abstract:Advancement of EGS requires improved prediction of fracture development and growth during reservoir stimulation and long-term operation. This, in turn, requires better understanding of the dynamics of the strongly coupled thermo-hydro-mechanical (THM) processes within fractured rocks. We have developed a physically based rock deformation and fracture propagation simulator by using a quasi-static discrete element model (DEM) to model mechanical rock deformation and fracture propagation induced by thermal stress and fluid pressure changes. We also developed a network model to simulate fluid flow and heat transport in both fractures and porous rock. In this paper, we describe results of simulations in which the DEM model and network flow & heat transport model are coupled together to provide realistic simulation of the changes of apertures and permeability of fractures and fracture networks induced by thermal cooling and fluid pressure changes within fractures. Various processes, such as Stokes flow in low velocity pores, convection-dominated heat transport in fractures, heat exchange between fluid-filled fractures and solid rock, heat conduction through low-permeability matrices and associated mechanical deformations are all incorporated into the coupled model. The effects of confining stresses, developing thermal stress and injection pressure on the permeability evolution of fracture and fracture networks are systematically investigated. Results are summarized in terms of implications for the development and evolution of fracture distribution during hydrofracturing and thermal stimulation for EGS.
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Country of Publication:US
Language:English
Size/Format:Medium: ED
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System Entry Date:2013 Apr 04
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