Permeability, compressibility, and friction coefficient measurements under confining pressure and strain, Leg 190, Nankai Trough.

Sylvain Bourlange (1) , Laurence Jouniaux (2) , Pierre Henry (3)

1 GOCAD - GOCAD
2 GE
3 Collège de France - Chaire Géodynamique

Permeability measured on three samples in a triaxial cell under effective confining pressure from 0.2 to 2.5 MPa ranges from 10E-18 to 10E-19m2. Overall, results indicate that permeability decreases with effective confining pressure up to 1.5 MPa; however, measurements at low effec-tive pressure are too dispersed to yield a precise general relationship between permeability and pressure. When the effective pressure is increased from 1.5 to 2.5 MPa, permeability is roughly constant (~1-4 x 10E-19 m2). Samples deformed in the triaxial cell developed slickenlined fractures, and permeability measurements were performed before and after failure. A permeability increase is observed when the sample fails under low effective confining pressure (0.2 MPa), but not under effective pressure corresponding to the overburden stress. Under isotropic stress conditions, permeability decrease related to fracture closure occurs at a relatively high effective pressure of ~1.5 MPa. Coefficients of friction on the fractures formed in the triaxial cell are ~0.4.

Mots clés: Géodynamique; Géomateriaux; Géosciences marines; Milieux poreux; Tectonique; tectonophysique; nankai; permeability; accretionary wedge; compressibility; friction; fluid flow; clay

Domaines: Géophysique [physics.geo-ph]; Géophysique [physics.geo-ph]; Tectonique; Milieux et Changements globaux

Sylvain Bourlange, Laurence Jouniaux, Pierre Henry. Permeability, compressibility, and friction coefficient measurements under confining pressure and strain, Leg 190, Nankai Trough.. Proceedings of the Ocean Drilling Program. Scientific results, 2004, 190/196, p.1-16. ⟨hal-00108311⟩