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Crack band approach to complex 3D hydraulic fracturing of gas shale

The advances in hydraulic fracturing of oil and gas bearing rocks, aka "fracking”, have been nothing less than astonishing. These advances have made the US self-sufficient in energy for the first time in decades.
A fundamental understanding of the failure and flow phenomena occurring in the shale formation at several length scales is required to improve the current technology for both efficiency and environment. However, modeling the three-dimensional (3D) hydraulic fracture has always been one of the most challenging issues in oil and gas industry.
This contribution proposes a multi-physics approach to model 3D fluid-driven fracture propagating in low permeable shale. The complex nonlinear and anisotropic mechanical behavior of shale is captured by means of a microplane model. The fracture of the solid is modeled by using the crack bank model, treating the cracks in a smeared way whereas the 3D nonlinear fluid-flow governing equation is constructed by combining the fluid mass balance equation with the Poiseuille flow equation.
Preliminary numerical simulations of hydraulic fracturing starting from a horizontal borehole show that the proposed approach provides a very realistic picture of the fracturing process.

Author(s):

Zdenek P. Bažant    
Northwestern University
United States

Viet T. Chau    
Northwestern University
United States

Yewang Su    
Northwestern University
United States

Marco Salviato    
Northwestern University
United States