Experimental study on the effects of pre-cracks, fracturing fluid, and rock mechanical characteristics on directional hydraulic fracturing with axial pre-cracks

Directional hydraulic fracturing by prefabricating longitudinal (axial) cracks on the sides of boreholes is an effective technique to control hard roof and ensure mining safety. In the present work, a true triaxial hydraulic fracturing experimental device was used to study the influence of prefabricated crack (pre-crack) parameters (including inclination angle and crack length), fracturing fluid viscosity, and mechanical characteristics of rocks...