Numerical study of hydraulic fracture propagation in inherently laminated rocks accounting for bedding plane properties

Abstract

The objective of this paper is to investigate hydraulic fracture propagation in inherently laminated rocks considering different bedding plane characteristics. To this end, a layered particle-based numerical model is first established in the framework of particle flow simulation. The mechanical behavior of rock matrix is controlled by randomly distributed bond contacts while that of bedding planes by preferentially orientated smooth joint contacts. On this basis, an improved hydromechanical coupled model is then proposed by modelling of hydraulic pipes according to contact types, which can well describe the fluid flow difference of rock matrix and bedding planes. The efficiency of improved model is assessed by comparisons with the Blanton's criterion and typical experimental evidences. Numerical predictions are in good agreement with analytical solutions. The interaction modes between induced fractures and bedding planes are also captured successfully. Hydraulic fracturing simulations of laminated rocks are then conducted and quantitatively analyzed in terms of borehole pressure and fracture propagation. Some key parameters such as the elastic, strength, permeability and thickness of bedding planes effect on hydraulic fracturing process are further investigated and discussed. • Improved coupling laws between hydraulic conductivity evolution and fracture aperture in different types of broken contact surfaces are proposed. • The differences of hydraulic fracture propagation and fluid flow in rock matrix and bedding planes are well described. • Effects of some key parameters related to bedding planes on hydraulic fracturing process are investigated.