Numerical simulation study on seepage evolution law of coal seam water injection based on UDF

Abstract

In order to reveal the seepage evolution law of high-pressure water injection and improve the effect of water injection and dust suppression in coal, based on triaxial compression and coal mining practices, this paper obtains the matching relationship between coal deformation and pore water pressure through coal-rock permeability test. The user-defined function module is used to compile the relationship into Fluent to simulate the fluid pressure field, velocity field and water distribution in the process of drilling water injection, and analyze the wetting range and seepage velocity in coal around the radial direction of drilling hole under different water injection pressures. The results show that the seepage field pressure increases with the increase of pore water pressure, and the rate of pressure change gradually decreases with the increase of time, and the variation of seepage field velocity shows a similar change law. With the continuous increase of pore water pressure, the porosity of coal increases, and the water content of coal increases gradually, and the distribution range is gradually expanded from around the borehole to both sides. The wetting process around the borehole of coal seam increases rapidly and then decreases slowly to reach a stable state.

Keywords

• coal seam water injection
• numerical simulation
• udf
• porosity
• seepage
• wetting distribution