It is believed that in many cases, hydraulic fracturing in shale causes the generation of a complex fracture network. One process that has been proposed as an explanation for network complexity is the termination of a propagating fracture when it reaches a preexisting fracture. Fracture termination has been described in laboratory experiments and mine-back studies and could lead to branching of the fracture network, generating complexity. However, network branching process could lead to reduced fluid recovery. Continuous pathways for flow must pass through fractures of a variety of orientations, with different closure pressures. We studied this process using CFRAC, a hydraulic fracturing simulator that couples fluid flow with the stresses induced by fracture deformation in large, complex discrete fracture network models. Simulations were performed with two different networks: (1) a complex, branching network of both new and preexisting fractures and (2) several linear, continuous fractures. The simulations show how fluid recovery can be drastically reduced by the closure of bottleneck fractures in the complex fracture network case. These results also demonstrate that identification of fracture "closure" from pressure transients at the wellbore does not necessarily indicate that open fractures are not remaining in the formation. This could have consequences for estimation of formation permeability and consequently for estimation of drainage volumes.
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