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An Empirical Model of Intrinsic Permeability in Reactive Clay‐Bearing Sands
Author(s) -
Raffensperger Jeff P.,
Ferrell Ray E.
Publication year - 1991
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/91wr01570
Subject(s) - permeameter , porosity , permeability (electromagnetism) , scanning electron microscope , mineralogy , materials science , adsorption , sediment , soil science , geology , hydraulic conductivity , composite material , chemistry , membrane , soil water , geomorphology , biochemistry , organic chemistry
Permeameter experiments were conducted to determine the permeability response of a clay‐bearing sand to changes in fluid composition. These experiments examined the effects of varying cation type and concentration using NaCl and CaCl 2 solutions, as well as the effects of freshwater flushing of sediments equilibrated with seawater and large versus small stepwise reductions in NaCl concentration. The major goal of the study was to correlate permeability with measured parameters of the pore microstructure. Sediment samples from the tests were analyzed using Brunauer, Emmett, Teller (BET) and ethylene glycol monoethyl ether (EGME) adsorption methods to determine specific surface area. Other samples were examined using scanning electron microscopy and digital image analysis methods. For image analysis, backscattered electron images were acquired and specific measurements of pore structure parameters (porosity, pore‐size distribution) were made. Stepwise multiple regression was used to construct an empirical model of permeability, which included terms of porosity, mean pore diameter, and specific surface area. The Kozeny‐Carman model was applied to the data and led to predicted permeabilities 2 to 3 orders of magnitude lower than measured values. This was attributed to the presence of dead‐end pores and the importance of flow through large conducting channels.