Abstract
Hydraulic fracturing is a widely used stimulation method to enhance the productivity of unconventional resources and it has become an indispensable part of well completion in shale oil and gas field development. The complex hydraulic fracture network is strongly influenced by the interaction between the hydraulic fracture (HF) and the bedding plane (BP). A criterion based on classical mechanics and fracture mechanics has been developed to determine whether a fracture will dilate, slip, or penetrate a weak structural interface (pre-existing BP). Two curves are plotted according to the criterion, dividing a graph with confining pressure difference and interaction angle as variables into three regions: dilation, shear slip, and penetration regions. This provides a straightforward assessment of the interaction between HF and BP. The validation of the criterion using numerical simulations for various confining pressure differences and interaction angles is described and discussed. When applied to numerical simulations, good agreement between the criterion and simulations is observed. The dependence of interaction on the confining pressure difference and the interaction angle is shown quantitatively using the criterion. A small confining pressure difference and interaction angle indicate that the BP is more prone to dilation, while a large confining pressure difference and interaction angle suggest that the BP is more likely to be penetrated. The shear slip interaction is more conducive to the formation of complex fracture networks. The criterion has reference significance for the optimization of fracturing scheme and reservoir reconstruction in layered shale.