X-ray imaging of water motion during capillary imbibition: A study on how compaction bands impact fluid flow in Bentheim sandstone

Autor: Jérôme Fortin, J. M. Mengus, Adeline Pons, Beatriz Menéndez, Christian David, Sergei Stanchits
Přispěvatelé: 3.2 Geomechanics and Rheology, 3.0 Geodynamics and Geomaterials, Departments, GFZ Publication Database, Deutsches GeoForschungsZentrum, Laboratoire Géosciences et Environnement Cergy (GEC), Fédération INSTITUT DES MATÉRIAUX DE CERGY-PONTOISE (I-MAT), CY Cergy Paris Université (CY)-CY Cergy Paris Université (CY), Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine
Rok vydání: 2011
Předmět:
Zdroj: Journal of Geophysical Research
Journal of Geophysical Research, American Geophysical Union, 2011, 116 (B3), ⟨10.1029/2010JB007973⟩
ISSN: 0148-0227
2156-2202
DOI: 10.1029/2010JB007973⟩
Popis: [1] To investigate the effect of compaction bands (CB) on fluid flow, capillary imbibition experiments were performed on Bentheim sandstone specimens (initial porosity ∼22.7%) using an industrial X-ray scanner. We used a three-step procedure combining (1) X-ray imaging of capillary rise in intact Bentheim sandstone, (2) formation of compaction band under triaxial tests, at 185 MPa effective pressure, with acoustic emissions (AE) recording for localization of the induced damage, and (3) again X-ray imaging of capillary rise in the damaged specimens after the unloading. The experiments were performed on intact cylindrical specimens, 5 cm in diameter and 10.5 cm in length, cored in different orientations (parallel or perpendicular to the bedding). Analysis of the images obtained at different stages of the capillary imbibition shows that the presence of CB slows down the imbibition and disturbs the geometry of water flow. In addition, we show that the CB geometry derived from X-ray density maps analysis is well correlated with the AE location obtained during triaxial test. The analysis of the water front kinetics was conducted using a simple theoretical model, which allowed us to confirm that compaction bands act as a barrier for fluid flow, not fully impermeable though. We estimate a contrast of permeability of a factor of ∼3 between the host rock and the compaction bands. This estimation of the permeability inside the compaction band is consistent with estimations done in similar sandstones from field studies but differs by 1 order of magnitude from estimations from previous laboratory measurements.
Databáze: OpenAIRE
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