Cyclic Injection to Enhance Hydraulic Fracturing Efficiency: Insights from Laboratory Experiments

Table 3

Results summary for the second batch of sandstone.

Specimen no.	Injection method	Injection flowrate or injection pressure	Breakdown pressure (MPa)	Tensile strength (MPa)	Compressive strength (MPa)
1	Conventional	2.4 mL/min	18.35	2.819	47.64
2	Conventional	2.4 mL/min	26.70	2.362	48.93
5	Conventional	2.4 mL/min	36.40	2.557	46.92
3	Stepped pressure	2-4-6-8-11-13-15-17 MPa	25.36	1.785	48.76
4	Stepped pressure	2-4-6-8-11-13-15-17 MPa	26.10	1.614	44.07
6	Constant pressure	16 MPa	24.13	2.245	54.28