A 3D approach to study the interaction between hydraulic and natural fracture

Abstract

A real 3D model is developed to study the interaction between hydraulic fracture and natural fracture. The hydraulic fracture propagation behavior and fracture geometry under impact of natural fracture are studied through a series of numerical results, different horizontal stress anisotropies, intersection angles, friction coefficients as well as hydraulic parameters. The final results demonstrate the key role of horizontal stress anisotropy on the interaction between hydraulic fracture and natural fracture. Under a higher intersection angle, it is difficult for hydraulic fracture to cross the natural fracture with low horizontal stress anisotropy. In addition, the natural fracture at a lower intersection angle has a higher probability to capture the hydraulic fracture. Normally, the natural fracture is more likely to be activated in the top branch at a low intersection angle, as the lower branch is located in the induced stress shadow of hydraulic fracture. By contrast, two different branches,+ especially two symmetrical braches at the intersection of 90°, are activated. On the other hand, a higher friction coefficient slows down the propagation in natural fracture, even prevents the activation of natural fracture. Besides, increased injection rate as well as fluid viscosity will promote the fracture propagation under the same conditions to lead to a longer and wider fracture.