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Abstract In this paper, we investigate the effects of poroelastic properties and permeability on hydraulic fracturing in an anisotropic medium. A hybrid approach combining the EDFM (embedded discrete fracture model) and XFEM (extended finite element method) is proposed. Fractures are embedded into a nonconforming grid used to determine the fluid flow in a porous matrix by the mimetic finite difference method, accounting for an anisotropic permeability tensor. The stress-strain problem is solved by the extended finite element method with the same grid. The fluid flow and rock deformation as well as the fracture propagation are iteratively coupled. The proposed approach is validated against the analytical solutions for Mandel's problem and the KDG model. A series of calculations are performed, and the obtained results are analyzed to investigate the effects of the anisotropy of permeability, that of the elastic modulus and Biot's coefficient on the hydraulic fracturing process. It is found that the anisotropy of permeability has a significant influence on the geometrical parameter of a fracture, while the anisotropy of the elastic modulus has a dominating influence on the propagation direction of a fracture. Biot's coefficient also has an influence on the fracture propagation kinetics. [ABSTRACT FROM AUTHOR]

Fracture penetration or deflection may occur when the hydraulic fracture approaches weak interface in multi-layered formation. However, the intrinsic mechanism of fracture propagation pattern remains unclear. A model was presented to investigate hydraulic fracture propagation in multi-layered formation via the phase field method. The interface is explicitly represented by a weak thin layer. Fluid flow in the fractured media was modeled by using the indicator function of phase field. The iterative algorithm was described and validated against the benchmark cases. Simulation results show that the evolution of injection pressure is more complex when the fracture deflects than that when the fracture penetrates the interface. The fracture is prone to penetrate the softer layer the perforated layer while deflects to the interface if the adjacent layer is stiffer. Decreasing the modulus ratio of interface to layers promotes the fracture deflecting to the interface, while increasing the stress ratio contributes to the fracture penetrating the interface. The stacking mode of layers greatly affects the fracture propagation morphology in three or more layered formations. Rock heterogeneity doesn't alter the fracture propagation pattern as a whole, but it affects the local fracture morphology. The results provide a cloud chart of the relationship between fracture propagation pattern and controlling factors for the potential of field application. [ABSTRACT FROM AUTHOR]