Matrix diffusion in northern Negev fractured chalk and its correlation to porosity

Amir Polak, Ronit Nativ, Rony Wallach*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

30 Scopus citations

Abstract

In this paper we report on vertical variations in the values of the effective diffusion coefficient determined on 19 chalk samples collected throughout most of the Eocene section (285 m) in the northern Negev desert, Israel. The dependence of the measured values on sample depth, porosity, permeability and mineralogy was also evaluated. Finally, a correlation between the measured effective diffusion coefficient and porosity is suggested for these samples. The calculated values of the diffusion coefficient ranged from 1.22 to 2.55 × 10-6 cm2/s. These values are significantly higher than those measured on consolidated rock samples, and similar to values reported for British Cretaceous chalk. Our results demonstrate that the effective diffusion coefficient values for the Eocene chalk in the northern Negev desert, Israel are exclusively dependent on the porosity of the chalk matrix by Dc = D0ε2 (m = 2 in Archie's law) and not on its mineralogy or permeability. The fitted exponent, m, falls between the two extreme values of 1.5 and 2.5 that were mentioned by [Diffusion in Natural Porous Media (1998)] for porous media. However, a linear relationship between the effective diffusion coefficient and porosity fits better the data within the range of the measured of porosities. These correlations provide an easier and less costly method of estimating the diffusion coefficient in chalk samples from the Eocene Group in the northern Negev desert, Israel.

Original languageAmerican English
Pages (from-to)203-213
Number of pages11
JournalJournal of Hydrology
Volume268
Issue number1-4
DOIs
StatePublished - 1 Nov 2002

Bibliographical note

Funding Information:
Funding for this research was provided by The Ramat Hovav Industrial Council and the EU, under contract No. ENV-CT97-0441. Many thanks go to John Bloomfield and Kate Griffith and other associates at the British Geological Survey for helping us with the analysis of porosity and pore-size distribution. We wish to thank Josep M. Soler and Vincent C. Tidwell for their helpful review comments.

Keywords

  • Chalk
  • Contaminant transport
  • Diffusion
  • Israel
  • Matrix diffusion
  • Porosity

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