基于UDF的煤层注水渗流演化规律的数值模拟研究

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

    • 摘要: 为了更好地揭示煤体高压注水渗流演化规律,提高煤层注水抑尘效果;基于三轴压缩和煤矿生产实际,通过煤岩渗透性试验得到煤岩变形与孔隙水压匹配关系;利用用户自定义函数UDF模块将其编译到Fluent中对钻孔注水过程中的流体压力场、速度场及水量分布情况进行模拟,分析不同注水压力下钻孔径向周围煤体内润湿范围以及渗流速度等因素。结果表明:渗流场压力随着孔隙水压的增大而增大,压力变化率随着时间段的增长逐渐降低并趋至稳定,渗流场速度变化展现出相似的变化规律;随着孔隙水压的不断增大,煤体孔隙率随之增大,煤体内部含水率逐渐升高,分布范围从钻孔周围逐渐向两侧扩大,煤层钻孔周围的润湿过程是一个快速增长后缓慢降低达到稳定的状态。

       

      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.

       

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