Variation in the Permeability of Intact and Fractured Rocks due to Transient Disturbances in Axial Stress or Pore Pressure

Table 4

Experimental conditions for the Kushiro Cretaceous sandstone.

Axial stress disturbances							Pore pressure disturbances
Samples	Constant hydrostatic stress			Transient axial stress			Constant hydrostatic stress			Transient pore pressure
	Pp	PC	σA	ΔσA	σA-min	σA-max	Samples	Pp	PC	ΔPP	PP-min	PP-max	f
AS-KCS1		3	3	1	2	4	Pp-KCS1	1	10	0.2	0.9	1.1	0.15
AS-KCS2	1	10	10	0	10	10	Pp-KCS2			0.6	0.7	1.3	0.09
AS-KCS3				1	9.5	10.5	Pp-KCS3			0.8	0.9	1.7	0.05
AS-KCS4				3	8.5	11.5	Pp-KCS4			1	0.5	1.5	0.18
AS-KCS5				4	8	12	Pp-KCS5			1.4	0.3	1.7	0.09
AS-KCS6				5	7.5	12.5	Pp-KCS6			1.8	0.1	1.9	0.1
AS-KCS7				7	6.5	13.5	Pp-KCS7			1.8	0.1	1.9	0.1
AS-KCS8				9	5.5	14.5	Pp-KCS8			1.86	0.07	1.93	0.12
AS-KCS9				11	4.5	15.5	Pp-KCS9			1.88	0.07	1.95	0.1
AS-KCS10		15	15	1	14.5	15.5
AS-KCS11				5	12.5	17.5

P_C: confining pressure; P_P: pore pressure; Δσ_A: axial stress disturbance amplitude; ΔP_P: pore pressure disturbance amplitude; P_P-min: minimum pore pressure; P_P-max: maximum pore pressure; f: frequency. Unit of stresses is in mega Pascal (MPa) and frequency is in hertz (Hz).