Pore seepage law based on 3D printed micro-pore model

The study of porous media seepage law is the basis for oil, gas and water resources exploitation and water disaster prevention while a physical model test is an important means to carry out the research on it.Based on the CT image of real sand sample, through the steps of shearing→binarization→boundary extraction→modeling, a two-dimensional pore model was constructed.Using a high-precision light-solid 3D printer and rigid photosensitive material, a transparent fine pore test model was constructed.With a test platform including water injection system, pressure monitoring system, observation system, pore test model and pipeline, 12 injection water flow gradients and 4 seepage directions were tested for seepage model, which realized the observation of pore seepage process and high-density real-time monitoring of water injection pressure.The study found that ① in the process of porous media seepage, diversion and confluence continue to occur.The experiment model has a large difference in the active degree of pore seepage at different positions; ② the relationship between hydraulic gradient and permeability coefficient is a power function, and the larger the hydraulic gradient, the stronger the correlation; ③ the relationship between seepage velocity and hydraulic gradient is a highly correlated quadratic function.When the plane changes the injection direction at 90°, the hydraulic gradient varies greatly, showing obvious anisotropic characteristics; and ④ the porous model is a mixed flow of "laminar flow+turbulent flow", with the increase of seepage velocity, the proportion of turbulent flow in hydraulic gradient increases, which is mainly related to the characteristics of pore structure. © 2020, Editorial Office of Journal of China Coal Society. All right reserved.