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A two-dimensional BEM model has been developed to examine re-initiation or termination of a fluid-driven fracture that intersects an orthogonal frictional interface. The matrix rocks on both sides of the interface are assumed to be impermeable, and a Newtonian fluid is injected into the fracture system at a constant rate. The formation of a new crack is controlled by the critical tensile stress criterion. A fracture approaching and terminating on the interface can induce a horizontal tensile stress in the unfractured layer to facilitate fracture nucleation. As a result of the elevated tensile stress, a hydraulic fracture crossing interfaces between dissimilar layers either forms a step-like trace or propagates straight across. Its continued propagation into the interior of the unfractured layer is assisted by interface frictional sliding and pressurised fluid. Also, a fracture can be arrested by entering and extending along the interface if conditions do not lead to crack nucleation in the unfractured layer and growth of such a new fracture. In the presence of modulus contrasts across the interface, numerical results are presented for the changes in fracture trajectories and injection pressure.
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