Numerical simulations of hydraulic fracturing in large objects using an extended finite element method

Hydraulic fracturing of shale is simulated using an extended finite element method (XFEM) with an explicit user element in ABAQUS. The XFEM has extra degrees of freedom introduced into a conventional three-dimensional solid element with eight nodes to capture the arbitrary complex crack propagation during hydraulic fracturing in shale. The fluid flow inside the hydraulic fractures is simulated by solving the fluid continuity equation using the finite difference method (FDM). The extended method introduces phantom nodes to deal with a crack in the element. One point integration and hourglass control are used to improve the computational efficiency. The simulation results are in good agreement with experiments.