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Permeability of gypsum samples dehydrated in air
Author(s) -
Milsch Harald,
Priegnitz Mike,
Blöcher Guido
Publication year - 2011
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2011gl048797
Subject(s) - porosity , dehydration , permeability (electromagnetism) , gypsum , anhydrite , mineralogy , materials science , chemistry , composite material , membrane , biochemistry
We report on changes in rock permeability induced by devolatilization reactions using gypsum as a reference analog material. Cylindrical samples of natural alabaster were dehydrated in air (dry) for up to 800 h at ambient pressure and temperatures between 378 and 423 K. Subsequently, the reaction kinetics, so induced changes in porosity, and the concurrent evolution of sample permeability were constrained. Weighing the heated samples in predefined time intervals yielded the reaction progress where the stoichiometric mass balance indicated an ultimate and complete dehydration to anhydrite regardless of temperature. Porosity showed to continuously increase with reaction progress from approximately 2% to 30%, whilst the initial bulk volume remained unchanged. Within these limits permeability significantly increased with porosity by almost three orders of magnitude from approximately 7 × 10 −19 m 2 to 3 × 10 −16 m 2 . We show that ‐ when mechanical and hydraulic feedbacks can be excluded ‐ permeability, reaction progress, and porosity are related unequivocally.