Quantitative characterization of irregular microfracture network and its effect on the permeability of porous media

Abstract

Based on the comprehensive understanding on microfractures and matrix pores in reservoir rocks, numerical algorithms are used to construct fractured porous media and fracture-pore media models. Connectivity coefficient and strike factor are introduced into the models to quantitatively characterize the connectivity and strike of fracture network, respectively. The influences of fracture aperture, fracture strike and fracture connectivity on the permeability of porous media are studied by using multi-relaxation-time lattice Boltzmann model to simulate fluid flow in them. The greater the strike factor and the smaller the tortuosity of the fractured porous media, the greater the permeability of the fractured porous media. The greater the connectivity coefficient of the fracture network is, the greater the permeability of the fracture-pore media is, and the more likely dominant channel effect occurs. The fracture network connectivity has stronger influence on seepage ability of fracture-pore media than fracture aperture and fracture strike. The tortuosity and strike factor of fracture network in fractured porous media are in polynomial relation, while the permeability and fracture network connectivity coefficient of the fracture-pore media meet an exponential relation.

Keywords

• microfracture
• fracture network connectivity
• fracture network strike
• lattice Boltzmann model
• permeability