The importance of the degree of cataclasis in shear bands for fluid flow in porous sandstone, Provence, France - Archive ouverte HAL Access content directly
Journal Articles AAPG Bulletin Year : 2012

The importance of the degree of cataclasis in shear bands for fluid flow in porous sandstone, Provence, France

Gregory Ballas
  • Function : Author
  • PersonId : 934352
Roger Soliva
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  • PersonId : 862793
Jean-Pierre Sizun
Antonio Benedict
  • Function : Author
Thibault Cavailhes
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  • PersonId : 934353
Suzanne Raynaud
  • Function : Author
  • PersonId : 862798

Abstract

Determination of the membrane seal capacity of deformation bands is critical for managing geologic reservoirs in porous sandstones. In this study, we have analyzed a cataclastic shear-band network developed in uncemented porous sandstone in Provence, France. Geometrical analyses of the bands show significant differences between three types of bands (single strand, multistrand, and band cluster), sorted by their number of strands, their amount of shear displacement, and their thicknesses. At the microscopic scale, the image-analysis porosities and the grain-size distributions allow definition of three different types of microstructural deformation: damage zone, protocataclastic, and cataclastic. Whereas damage zone and protocataclastic deformations are observed in each type of band, cataclastic strands are observed in clusters and, sometimes, in multistrands. Cataclastic strands are characterized by a porosity reduction of 10 to 25% and a permeability reduction of three to five orders of magnitude compared to the host rock. Field observations of iron hydroxide precipitations around the bands suggest that cataclastic strands were membrane seals to water flow under vadose condition. This study therefore highlights the importance of the degree of cataclasis in shear bands as membrane seals to subsurface fluid flows in sandstone reservoirs.
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hal-00766557 , version 1 (18-12-2012)

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Gregory Ballas, Roger Soliva, Jean-Pierre Sizun, Antonio Benedict, Thibault Cavailhes, et al.. The importance of the degree of cataclasis in shear bands for fluid flow in porous sandstone, Provence, France. AAPG Bulletin, 2012, 96 (11), pp.2167-2186. ⟨10.1306/04051211097⟩. ⟨hal-00766557⟩
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