Visualized experimental study on initial seepage characteristics of liquid under micro-equivalent tube bundle

Research on the micro-seepage characteristics of low-permeability coal bodies is of great value to coal seam water injection and gas disaster prevention. Physical model simulation experiments are one of the important ways to carry out this research. In order to study the initial seepage characteristics of the liquid at the microscopic scale of coal pores, this paper uses microfluidic technology as the basis to make an equivalent capillary bundle model to replace coal pores, and build a microscopic seepage visualization experimental platform. We carried out seepage model experiments with different pore sizes and different fluids, and analyzed the influence of multiple parameters such as seepage flow rate, seepage pressure, pore size, wettability, etc. on seepage characteristics. The research results show that: ① The activity of pore seepage at different positions in the seepage process is quite different, and the seepage at the middle of the model is more active; the larger the initial flow of seepage, the more the number of channels participating in seepage. The initial flow of seepage is proportional to the volume of fluid in the capillary; ② When the initial flow is constant, the relationship between seepage pressure and time in different apertures is the same, that is, seepage pressure increases with time. The larger the initial seepage flow rate, the higher the system seepage pressure; the seepage flow in the capillary bundle shows obvious nonlinear seepage characteristics;③ The relationship between seepage flow and seepage pressure is very close under different model pore sizes; The flow and pressure of deionized water in the tube bundle model show different degrees of non-linear characteristics, and the smaller the pore size, the stronger the degree of non-linearity; ④ In terms of the influence of fluid wettability, the experimental results of different model pores are all It shows that the fluid with good wettability has lower seepage pressure in the capillary pore model. Compared with the pore size, the initial flow rate of seepage has a greater influence on fluid seepage pressure.