Fracture re-initiation as a possible branching mechanism during hydraulic fracturing

Hydraulic fracturing in naturally fractured reservoirs can be significantly different from that in non-fractured reservoirs. New diagnostic tools have verified complicated network of stimulated fractures in naturally fractured reservoirs. Here, we are trying to give a physical explanation of erratic changes in the orientation of hydraulic fracture growth. When hydraulic fractures intersect sealed natural fractures, a kink is formed in the fracture path. These kinks are the locations of stress singularity which makes them a secondary choice for fracture propagation. Results demonstrate that fracture pattern complexity is strongly controlled by the magnitude of anisotropy of in situ stresses, rock toughness, fracture cement strength as well as geometry of natural fractures.