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Laboratory observations of permeability enhancement by fluid pressure oscillation of in situ fractured rock

Elkhoury, Jean E. and Niemeijer, André and Brodsky, Emily E. and Marone, Chris (2011) Laboratory observations of permeability enhancement by fluid pressure oscillation of in situ fractured rock. Journal of Geophysical Research B, 116 (B2). Art. No. B02311 . ISSN 0148-0227.

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We report on laboratory experiments designed to investigate the influence of pore pressure oscillations on the effective permeability of fractured rock. Berea sandstone samples were fractured in situ under triaxial stresses of tens of megapascals, and deionized water was forced through the incipient fracture under conditions of steady and oscillating pore pressure. We find that short-term pore pressure oscillations induce long-term transient increases in effective permeability of the fractured samples. The magnitude of the effective permeability enhancements scales with the amplitude of pore pressure oscillations, and changes persist well after the stress perturbation. The maximum value of effective permeability enhancement is 5 × 10^(−16) m^2 with a background permeability of 1 × 10^(−15) m^2; that is, the maximum enhanced permeability is 1.5 × 10^(−15) m^2. We evaluate poroelastic effects and show that hydraulic storage release does not explain our observations. Effective permeability recovery following dynamic oscillations occurs as the inverse square root of time. The recovery indicates that a reversible mechanism, such as clogging/unclogging of fractures, as opposed to an irreversible one, like microfracturing, is responsible for the transient effective permeability increase. Our work suggests the feasibility of dynamically controlling the effective permeability of fractured systems. The result has consequences for models of earthquake triggering and permeability enhancement in fault zones due to dynamic shaking from near and distant earthquakes.

Item Type:Article
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URLURL TypeDescription DOIArticle
Brodsky, Emily E.0000-0002-6855-6860
Additional Information:© 2011 American Geophysical Union. Received 5 June 2010; revised 5 November 2010; accepted 22 December 2010; published 24 February 2011. We gratefully acknowledge experimental support by I. Faoro and J. Samuelson and comments from H. Kanamori and D. Elsworth. This work was supported in part by NSF grants OCE‐ 0648331 and EAR‐0545702. A.R.N. was supported by NWO (Dutch Science Foundation) grant 825.06.003.
Funding AgencyGrant Number
Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO)825.06.003
Subject Keywords:permeability enhancement; in situ fractured rock; dynamic stressing; laboratory observations
Issue or Number:B2
Record Number:CaltechAUTHORS:20110314-132429467
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Official Citation:Elkhoury, J. E., A. Niemeijer, E. E. Brodsky, and C. Marone (2011), Laboratory observations of permeability enhancement by fluid pressure oscillation of in situ fractured rock, J. Geophys. Res., 116, B02311, doi:10.1029/2010JB007759.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:22862
Deposited By: Tony Diaz
Deposited On:15 Mar 2011 21:38
Last Modified:03 Oct 2019 02:41

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