Abstract: In this paper, a set of fracture-matrix models were designed, and three kinds of quartz sand with different particle sizes were selected to fill the matrix region of the fracture-matrix system, and the influence of quartz sand with different particle sizes on the water flow characteristics in the fracture-matrix model was studied. The results show that the decision coefficients of the Forchheimer equation are higher than those of Darcy's law, and the Forchheimer equation fits the nonlinear fluid flow in the fracture-matrix system better than Darcy's law. The simulation results of the Kozeny-Carman model show that there is a linear relationship between the matrix permeability coefficient and the characteristic particle size in the fracture-matrix system across all three matrix particle sizes. The larger the hydraulic opening in the fracture-matrix system, the weaker the fracture permeability, the greater the non-Darcy seepage coefficient, and the more obvious the non-Darcy seepage phenomenon.
Keywords: matrix particle size; fracture-matrix system; permeability coefficient; non-Darcy coefficient; hydraulic opening