Simulation of Hydraulic Fracture Propagation in Fractured Coal ‎Seams with Continuum-discontinuum Elements

Abstract

Creating new fracture networks in coal seams with natural fractures through hydraulic fracturing techniques is an effective method for exploiting coal-bed methane. In this paper, a continuum-discontinuum element method (CDEM) is developed for simulating and assessing hydraulic fracture propagation in coal seams. An elastic-damage-fracture model is proposed for capturing the deformation and cracking processes of fractured coal. A stress-fracture percolation relation is implemented to simulate the hydro-mechanical coupling processes. The influence of X-direction angles, mechanical strengths, distances and lengths of natural fractures are analyzed in detail. The results are potentially useful to optimize the fracturing design.

Keywords

• continuum-discontinuum element method (cdem)
• hydraulic fracturing
• fractured coal
• hydro-mechanical coupling