A model for water flow through rock fractures based on friction factor

Zhenyu Zhang, Jan Nemcik, Qiuqiu Qiao, Xueyu Geng

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

Rock fracture roughness and tortuosity caused by contact asperities produce extra resistance for fluid flow in comparison with the channel consisting of two smooth parallel plates. To characterise the role of roughness and tortuosity in water flow through rock fractures, the existing studies of the effect of fracture roughness and contact area (tortuosity) on fluid flow through rock fractures were firstly reviewed. Then, an explicit flow model was derived using the friction factor predictor previously proposed according to the flow data of sandstone fractures. Regarding the introduced relative roughness of rock fracture as the correction variable, the developed flow model can be considered as a corrected form of classic cubic law, where the relative roughness is defined as the ratio of the averaged peak asperity height to equivalent hydraulic aperture. Sensitivity analysis shows that the cubic law can overestimate the flow rate by 10 % when the relative roughness increases to 70.7. With further increase in relative roughness up to 300, which usually represents tight rock fractures, the flow rate is only approximately 64 % of that predicted by cubic law. The verification of this friction factor to granite and limestone fractures shows that the used friction factor predictor is in good accordance with the experimental data.
Original languageEnglish
Pages (from-to)559–571
JournalRock Mechanics and Rock Engineering
Volume48
Issue number2
Early online date6 Mar 2014
DOIs
Publication statusPublished - Mar 2015
Externally publishedYes

Fingerprint

water flow
friction
roughness
Rocks
Friction
Surface roughness
rock
tortuosity
Water
asperity
Contacts (fluid mechanics)
fluid flow
Flow of fluids
Flow rate
Granite
Sandstone
Limestone
Sensitivity analysis
sensitivity analysis
granite

Cite this

Zhang, Zhenyu ; Nemcik, Jan ; Qiao, Qiuqiu ; Geng, Xueyu. / A model for water flow through rock fractures based on friction factor. In: Rock Mechanics and Rock Engineering. 2015 ; Vol. 48, No. 2. pp. 559–571.
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A model for water flow through rock fractures based on friction factor. / Zhang, Zhenyu; Nemcik, Jan; Qiao, Qiuqiu; Geng, Xueyu.

In: Rock Mechanics and Rock Engineering, Vol. 48, No. 2, 03.2015, p. 559–571.

Research output: Contribution to journalArticle

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AU - Zhang, Zhenyu

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AB - Rock fracture roughness and tortuosity caused by contact asperities produce extra resistance for fluid flow in comparison with the channel consisting of two smooth parallel plates. To characterise the role of roughness and tortuosity in water flow through rock fractures, the existing studies of the effect of fracture roughness and contact area (tortuosity) on fluid flow through rock fractures were firstly reviewed. Then, an explicit flow model was derived using the friction factor predictor previously proposed according to the flow data of sandstone fractures. Regarding the introduced relative roughness of rock fracture as the correction variable, the developed flow model can be considered as a corrected form of classic cubic law, where the relative roughness is defined as the ratio of the averaged peak asperity height to equivalent hydraulic aperture. Sensitivity analysis shows that the cubic law can overestimate the flow rate by 10 % when the relative roughness increases to 70.7. With further increase in relative roughness up to 300, which usually represents tight rock fractures, the flow rate is only approximately 64 % of that predicted by cubic law. The verification of this friction factor to granite and limestone fractures shows that the used friction factor predictor is in good accordance with the experimental data.

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