Unconventional petroleum resources occur in formations that are layered and or contain natural fractures posing challenges to modeling of reservoir stimulation. In this paper, we use a 3D fully coupled hydro-mechanical model to analyze hydraulic fracturing propagation in a layered rock and consider the impact of different layer rock properties and interface conditions on hydraulic fracture growth. The 3D fully coupled hydro-mechanical simulator, which can model elastic as well as poroelastic formations, is implanted based on the finite element method using a parallel computation framework. A special zero-thickness interface element is developed to simulate the fracture propagation and the fluid flow in the created hydraulic fracture. A standard local traction-separation law with strain-softening is used to capture the main characteristics of tensile cracking. Numerical examples are used to verify the hydro-mechanical model through comparison with analytical asymptotic solutions. Good agreement has been achieved with respect to fluid pressure, fracture height, half-length and width distributions. The influences of rock properties and in-situ stresses on fracture propagation are also analyzed. Numerical results indicates that, for hydraulic fracturing in multiple-layered formations with different minimum horizontal stresses, the propagation of hydraulic fracture tends to be confined to the formation with lower minimum horizontal stresses. For multiple-layered formations with different Young’s modulus, the hydraulic fracture tends to propagate in the formation with lower Young’s modulus. The aperture size in the formation with the lowest Young’s modulus is larger than those in other formations.
Parallel Finite Element Simulations of 3D Hydraulic Fracture Propagation Using a Coupled Hydro-Mechanical Interface Element
Gao, Q., and A. Ghassemi. "Parallel Finite Element Simulations of 3D Hydraulic Fracture Propagation Using a Coupled Hydro-Mechanical Interface Element." Paper presented at the 52nd U.S. Rock Mechanics/Geomechanics Symposium, Seattle, Washington, June 2018.
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