Table 2.

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

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

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.