Abstract Investigations of void distributions and formation mechanisms of proppant particles in closure fractures have extremely major significance for improving the production of coalbed methane. In this study, a numerical method was developed to simulate compaction processes of a proppant-filled fracture under different closure stresses. The particle trajectories, force chains and coordination numbers of proppants were extracted to analyze and investigate void ratio distributions and associated formation mechanisms. The results showed that during fracture closures from the top to bottom, some particles in the top layer of the proppant-filled fracture moved into the middle layer, which made the middle layer particles formed solid force-bearing structures. The greatest force was transmitted between particles in the middle layer. This was followed by particles in the top layer and finally, the bottom layer. In addition, the proportions of large coordination numbers, and average coordination numbers of the middle layer were the largest, followed by those of the top and bottom layers, which reflected that the particles of the middle layer were denser than those of the other two layers. The above factors caused the void ratios of the middle layer to be the lowest, followed by those of the top and bottom layer, respectively.

中文翻译：

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支撑剂颗粒孔隙分布形成机理的数值模拟研究

摘要 研究闭合裂缝中支撑剂颗粒的孔隙分布及形成机制，对于提高煤层气产量具有极其重要的意义。在这项研究中，开发了一种数值方法来模拟不同闭合应力下支撑剂填充裂缝的压实过程。提取了支撑剂的粒子轨迹、力链和配位数，以分析和研究空隙率分布和相关的形成机制。结果表明，在裂缝自上而下闭合过程中，支撑剂填充裂缝顶层的一些颗粒向中层移动，使中层颗粒形成坚固的受力结构。最大的力在中间层的粒子之间传递。紧随其后的是顶层中的颗粒，最后是底层。此外，中间层的大配位数和平均配位数的比例最大，其次是顶层和底层，这反映了中间层的颗粒比其他两层的颗粒更密集。 . 以上因素导致中间层的空隙率最低，其次是顶层和底层。