Enhancement of fluid permeability during shear deformation of a synthetic mud
Date
2000
Authors
Zhang, Shuqing
Cox, Stephen
Journal Title
Journal ISSN
Volume Title
Publisher
Royal Asiatic Society
Abstract
This study concerns the effect of stress paths on permeability and permeability anisotropy in a synthetic mud at conditions where cataclastic flow is dominant. The synthetic mud is composed of 10 wt.% montmorillonite, 40 wt.% illite, and 50 wt.% silt-sized quartz. In the experiments where the mud was first consolidated at 90 MPa effective pressure (pe) and then also sheared at 90 MPa pe, permeability decreased continuously with increasing shear displacement; subsequent shear deformation at 30 MPa and 20 MPa effective pressure resulted in permeability increases. The permeabilities parallel to and across the mud layer are similar during shear deformation at 90 MPa pe and remain so during shear deformation at lower pe. In the experiments where shear deformation commenced at 30 MPa pe after an initial consolidation at 90 MPa, permeability increased significantly with increasing displacement. Combined effects of reducing mean effective stress and shear sliding result in permeability enhancement up to two orders of magnitude. The permeability parallel to the shear direction is one order of magnitude higher than that across the shear plane. Our shear deformation experiments at high pressures confirm the importance of stress path on the evolution of fluid permeability during shear deformation. The experimental results clearly indicate that to effectively enhance permeability and to channel fluids along shear zones in wet sediments, mean effective stress needs to be less than several tens of MPa.
Description
Keywords
Keywords: Synthetic mud; Consolidation; Mechanical permeability; Shear deformation; Shear stress; Structural geology; anisotropy; cataclasite; fluid flow; mudflow; permeability; shear; stress field
Citation
Collections
Source
Journal of the Malaysian Branch of the Royal Asiatic Society
Type
Journal article
Book Title
Entity type
Access Statement
License Rights
Restricted until
2037-12-31
Downloads
File
Description