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Summary The hydraulic fracturing propagation regimes in the plane strain model are uniformly investigated using a numerical method based on the finite element method. The regimes range from toughness‐dominated cases to viscosity‐dominated cases, covering zero leak‐off situations and small leak‐off situations. Unlike the asymptotic solutions, the numerical method is independent of the energy dissipation regimes and fluid storage regimes. The numerical method pays no special attention to the fracture tip, and it simulates fracture tip behaviors by increasing the number of functions in a natural and uniform manner. The numerical method is verified by comparing its results with the asymptotic solutions. The effect of the model sizes on the numerical method is discussed along with the robustness of the numerical method. Copyright © 2014 John Wiley & Sons, Ltd.

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Hydraulic fracturing with and without fluid lag have different flow boundary conditions at the fluid front, which always results in different simulation methods. In this paper, we extend a finite element method [1] to simulate hydraulic fracturing with and without fluid lag in a unified manner. A unified numerical boundary condition is imposed on the fluid front independent of fluid lag situations. No effort is needed to track the fluid front explicitly, and the burden of model re-meshing induced by fluid front advancement is avoided. The method is verified by comparing numerical simulations with some analytical solutions. The simulations cover hydraulic fracturing with constant fluid lag fraction, without fluid lag, and with vanishing fluid lag. Some factors governing the simulations are discussed.

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Multiple hydraulic fracturing is a proven stimulation technique to improve hydrocarbon production especially in tight, unconventional hydrocarbon bearing reservoirs. A two dimensional (2D) plane strain model, based on linear elastic fracture mechanics (LEFM), has been developed to study multiple fracture propagation and their impact on reactivation of underground discontinuities such as faults. New model solves coupled non-local relationship between fracture width and net pressure in the fracture and non-linear dependence of fluid flow on fracture width and its linear dependence on pressure gradient using finite element method.In this paper, multiple hydraulic fracturing with different number of fractures, fracture spacing and reservoir rock properties are considered. It is found that the number of hydraulic fractures and their spacing significantly impacts fractures geometry and ultimately production performance. The impact found to be more pronounced in heterogeneous reservoir with multiple layers. Slip-tendency analysis performed to investigate the possibility of fault reactivation and discontinuities failure in surrounding areas. Simulation results clearly show dynamics of stable and unstable zones around the hydraulic fracturing area. Discontinuities failure in reactivation zones leads to increase the permeability of formation therefore improving hydraulic fracturing performance. This study is a unique approach for our further understanding of multiple hydraulic fracturing, and it is important for the development of sound numerical hydraulic fracturing optimization models.