Directional distance prediction model of slotting-directional hydraulic fracturing (SDHF) for coalbed methane (CBM) extraction

Slotting-directional hydraulic fracturing (SDHF) is a promising technology for extracting CBM, because it can achieve directional propagation of fractures, and solve the problem of non-uniform permeability enhancement in hydraulic fracturing. In order to provide construction basis for SDHF, directional distance prediction model of SDHF was established in this work, and obtained an analytical solution for the directional distance. Similar simulation experiments using true triaxial test system in laboratory were conducted, high-energy CT scanning documented fracture morphology, the fracture directional distance was measured, and the reliability of the model was proved. The research results indicated that as the azimuth of slotted hole and the horizontal stress difference decreased, directional distance increased exponentially. With the increase of injection pressure and size of slotted hole, the directional distance increased linearly and quadratically, respectively. The established prediction model and findings reported in the paper will provide guidance for engineering applications.