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Porosity and permeability development in compacting chalks during flooding of nonequilibrium brines: Insights from long‐term experiment
Author(s) -
Nermoen Anders,
Korsnes Reidar I.,
Hiorth Aksel,
Madland Merete V.
Publication year - 2015
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.983
H-Index - 232
eISSN - 2169-9356
pISSN - 2169-9313
DOI - 10.1002/2014jb011631
Subject(s) - porosity , permeability (electromagnetism) , compaction , characterisation of pore space in soil , dissolution , volume (thermodynamics) , mineralogy , geology , outcrop , geotechnical engineering , materials science , thermodynamics , chemical engineering , chemistry , geochemistry , biochemistry , physics , membrane , engineering
We report the complete chemical alteration of a Liège outcrop chalk core resulting from a 1072 flow‐through experiment performed during mechanical compaction at 130°C. Chemical rock‐fluid interactions alter the volumetric strain, porosity, and permeability in a nontrivial way. The porosity reduced only from 41.32% to 40.14%, even though the plug compacted more than 25%. We present a novel analysis of the experimental data, which demonstrates that the geochemical alteration does not conserve the volume of the solids, and therefore, the strain is partitioned additively into a pore volume and solid volume component. At stresses beyond yield, the observed deformation can be explained by grain reorganization reducing the pore space between grains and solid volume changes from the rock‐fluid interactions. The mechanical and chemical effects are discussed in relation to the observed permeability development.