Development of hydraulic fracture zone in heterogeneous material based on smeared crack method

•Modification of K is an effective way to simulate the complex HF problems.•The damage parameter ξ dramatically influences the hydraulic conductivity history.•The fracture fronts become constrained between the unpenetrable strong layers.•The tensile strength has an important impact on the features of the fracture zone.

This paper presents a hydraulic fracture model based on a fully coupled, pore pressure-effective stress formulation. The stress-strain behavior of the solid phase is modeled using an elasto-plastic, Mohr-Coulomb description. Hydraulic conductivity is related to the difference between mean effective stress and tensile strength via a hyperbolic tangent function that takes into account the relative permeability using the Corey correlation. The effect of the damage coefficient ξ on fracture propagation is studied via the hyperbolic function and the sensitivity of the solution to the aspect ratio of the elements is checked. Three types of material distributions are considered: homogeneous domain in which the material properties are constant; heterogeneous domain where multi-layered materials with strong and weak layers are included; and multi-layered material in which the values of the material properties for each layer are randomly generated using a PYTHON script. The propagation mechanisms and fracture features are discussed. Finally the propagation process, the extent of the fracture zone and pore pressure changes from a series of numerical simulations using ABAQUS are presented.