Table 2 Argon gas permeability was measured by the pore pressure oscillation technique through an open fracture parallel to lamination of sample 4.

From: Quantifying the anisotropy and tortuosity of permeable pathways in clay-rich mudstones using models based on X-ray tomography

Effective pressure (MPa) 5 15 25 35 45
test 1 (m2) 1.4 × 10−18 7.8 × 10−19    
test 2 (m2) 1.9 × 10−18 6.3 × 10−19 2.5 × 10−19
test 3 (m2)   4.7 × 10−19 2.2 × 10−19 7.4 × 10−20 1.6 × 10−20
test 4 (m2) 1.1 × 10−19 4.4 × 10−20 1.8 × 10−20 4.0 × 10−21
  1. Measurements were taken continuously while the confining pressure was increased at 10 MPa increments from 10 MPa to 50 MPa. Pore pressure was set at 5 MPa with a 1 MPa oscillation amplitude at 1 hour wavelengths. The sample was left in the apparatus overnight at 5 MPa effective pressure between tests 1, 2 and 3. The sample was extracted from the apparatus after test 3 and reloaded for a 4th test.