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

Table 2

Correlation coefficients of the influencing factors with shale porosity.

		Permeability decline rate	Shut-in time	Backflow outlet pressures	Differential pressure during backflow
Pearson correlation	Rate of porosity decline	1.000	-0.069	-0.120	-0.242
	Shut-in time	-0.069	1.000	-0.152	-0.097
	Backflow outlet pressure	-0.120	-0.152	1.000	0.069
	Differential pressure during backflow	-0.242	-0.097	0.069	1.000
Significance; (single tail)	Rate of porosity decline	/	0.365	0.275	0.112
	Shut-in time	0.365	/	0.225	0.315
	Backflow outlet pressure	0.275	0.225	/	0.366
	Backflow differential pressure	0.112	0.315	0.366	/
Number of cases	Rate of porosity decline	27	27	27	27
	Shut-in time	27	27	27	27
	Backflow outlet pressure	27	27	27	27
	Differential pressure during backflow	27	27	27	27