DEM simulation of confining pressure effects on crack opening displacement in hydraulic fracturing

Hydraulic fracture is one of the key methods in well stimulation to increase production of oil and gas. Crack Opening Displacement (COD) is of great importance in this method since it is in direct relation with permeability and production rate. In this paper COD is measured by a distinct element model which has been validated by an exact solution. A comprehensive study has been performed on confining pressure effect on COD which is neglected in the analytical solution. Numerical results showed that confining pressure considerably affects COD. A multi-parameter regression (considering effect of confining pressure, rock mass properties and fluid pressure) was performed on numerical results which resulted in an equation. The proposed equation considers the effect of confining pressure and its results are in good agreement with numerical results. (C) 2016 Published by Elsevier B.V. on behalf of China University of Mining & Technology.