Interaction between Induced Hydraulic Fracture and Pre-Existing Natural Fracture in a Poro-elastic Environment: Effect of Pore Pressure Change and the Orientation of Natural Fracture

Abstract This paper investigates the effect of pore pressure change on the interaction of induced hydraulic fracture and natural fracture and the effect of natural fracture orientation. Warpiniski and Teufel's interaction criteria were adopted to evaluate the fracture propagation that would occur after an induced fracture intersects an existing natural fracture. A fully coupled finite element based model is used to simulate hydraulic fracture propagation in a poroelastic formation with existing natural fracture. In order to study the effect of pore pressure change on interaction zone, a poro-elastic solution for the stresses in the interaction zone has been used as a basis for fracture interaction criteria. From the results of this study, the followings were observed when the induced fracture interacts with the natural fracture with changing pore pressure. ○At low angles of approach with low to high differential stress, the induced fracture is arrested by the natural fracture, then the natural fracture begins to open, diverting the fracturing fluid and preventing the induced fracture from crossing.○At medium (60 deg and above) angles of approach fracture opening and crossing both was observed depending on the differential stress. In low differential stress opening occurred and in high differential stress (more than 600 psi) induced hydraulic fracture cross the natural fracture.○At high angles of approach crossing occurred at all differential stresses.○Pore pressure change does not have any direct impact on interaction type but it accelerates the reinnitiation pressure needed to cross the natural fracture. The pressure build up rate inside the natural fracture is influenced by the pore pressure change. This paper depicts that the effect of pore pressure change and the orientation of the natural fracture is of immense significance in hydraulic fracture propagation when it interacts with natural fracture. The study includes small to large natural fracture and low permeable formation.