Effects of grain size distribution on the permeability of compacting aggregates: Results from rock-analogue experiments and microphysical models

André Niemeijer, Chris Marone, Derek Elsworth

Research output: Chapter in Book/Report/Conference proceedingConference contributionAcademic

Abstract

We investigate the evolution of permeability with porosity and grain size in
compacting aggregates of brine-saturated salt. The porosity of aggregates with different
initial grain size distributions was reduced by a step-wise application of compactive strain,
retaining the effective normal stress steady state flow with a pore pressure differential of 0.1 MPa across two granular layers in
parallel. We found that permeability decreased with decreasing porosity according to a power
law relation, consistent with predictions from capillary models (i.e. Kozeny-Carman
Equation), but with an exponent that changes with porosity. The Kozeny-Carman model
overestimates observed permeabilities in all experiments by at least one order-of-magnitude
as a result of the assumed monodispersed distribution of grain diameters and therefore pore
throat sizes. We extend the Kozeny-Carman model using an expression for the tortuosity that
is dependent on the actual grain size. The broader grain size distributions, with abundant
small grains, returns lower permeabilities than those predicted using the average or median
grain size.
Original languageEnglish
Title of host publicationThe Mechanical Behavior of Salt X
Subtitle of host publicationProceedings of the 10th Conference on the Mechanical Behavior of Salt (SaltMech X), Utrecht, The Netherlands, 06-08 July 2022
Editors J.H.P. de Bresser, M.R. Drury, P. A. Fokker, M. Gazzani, S.J.T. Hangx, A.R. Niemeijer, C.J. Spiers
Place of PublicationLondon
PublisherCRC Press
Pages78-87
Number of pages10
Edition1
ISBN (Electronic)9781003295808
ISBN (Print)9781032282206
DOIs
Publication statusPublished - 5 Jul 2022
Event10th Conference on the Mechanical Behavior of Salt - Utrecht University, Utrecht, Netherlands
Duration: 6 Jul 20228 Jul 2022

Conference

Conference10th Conference on the Mechanical Behavior of Salt
Abbreviated titleSaltMech X
Country/TerritoryNetherlands
CityUtrecht
Period6/07/228/07/22

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