Mineral precipitation-induced porosity reduction and its effect on transport parameters in diffusion-controlled porous media

Geochemical Transactions
Aurélie ChagneauThorsten Schäfer

Abstract

In geochemically perturbed systems where porewater and mineral assemblages are unequilibrated the processes of mineral precipitation and dissolution may change important transport properties such as porosity and pore diffusion coefficients. These reactions might alter the sealing capabilities of the rock by complete pore-scale precipitation (cementation) of the system or by opening new migration pathways through mineral dissolution. In actual 1D continuum reactive transport codes the coupling of transport and porosity is generally accomplished through the empirical Archie's law. There is very little reported data on systems with changing porosity under well controlled conditions to constrain model input parameters. In this study celestite (SrSO4) was precipitated in the pore space of a compacted sand column under diffusion controlled conditions and the effect on the fluid migration properties was investigated by means of three complementary experimental approaches: (1) tritiated water (HTO) tracer through diffusion, (2) computed micro-tomography (µ-CT) imaging and (3) post-mortem analysis of the precipitate (selective dissolution, SEM/EDX). The through-diffusion experiments reached steady state after 15 days, at which point cel...Continue Reading

References

Jan 31, 2002·Journal of Contaminant Hydrology·T B Boving, P Grathwohl
Feb 25, 2003·Journal of Contaminant Hydrology·L R Van LoonM H Bradbury
Nov 30, 1945·Annals of the New York Academy of Sciences·L ONSAGER
Mar 20, 2013·Environmental Science and Pollution Research International·Carlos AyoraJose-Miguel Nieto
Oct 10, 2013·Journal of Environmental Management·Costantino Masciopinto
May 29, 2014·Environmental Science & Technology·Sergi MolinsCarl I Steefel

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