The Effect of Slickwater on Shale Properties and Main Influencing Factors in Hydraulic Fracturing

Table 4

Correlation coefficients of the influencing factors with shale permeability.

		Permeability decline rate	Shut-in time	Backflow outlet pressures	Backflow differential pressure
Pearson correlation	Permeability decline rate	1.000	-0.128	0.050	-0.019
	Shut-in time	-0.128	1.000	-0.152	-0.097
	Backflow outlet pressure	0.050	-0.152	1.000	0.069
	Differential pressure during backflow	0.019	-0.097	0.069	1.000
Significance; (single tail)	Permeability decline rate	/	0.262	0.402	0.463
	Shut-in time	0.262	/	0.225	0.315
	Backflow outlet pressure	0.402	0.225	/	0.366
	Backflow differential pressure	0.463	0.315	0.366	/
Number of cases	Permeability decline rate	27	27	27	27
	Shut-in time	27	27	27	27
	Backflow outlet pressure	27	27	27	27
	Backflow differential pressure	27	27	27	27