Calculation of equivalent permeability of different fracture intersections in fracutred porous media

Abstract

This paper reports a case study of calculation of equivalent permeability in Hot Dry Rock (HDR) system using an approach based on finite volume Computational Fluid Dynamics (CFD) method. In this case study, mass flow rates of water in two fractures crossing in a 300 mm x 300 mm two-dimensional (2D) block are predicted by CFD method for different pressure drops. The predicted mass flow rates are then used to calculate the equivalent permeability, Kx at x direction and Ky at y direction. A series of angles between these two fractures, α, are investigated and the results of α= 90, 60 and 50 degrees are reported in the paper. It is found that Kx slightly increases (by about 2%) when the angle of fractures decreases from 90 to 50 degrees. The values of Ky reduce by about 21% when the angle of fractures decreases, indicating the permeability is dependent on the heterogeneous property of the block. The developed approach is used to investigate the effects of pressure drops on the equivalent permeability. It is found the values of the equivalent permeability are slightly influenced by the pressure drop values in the investigated ranges.