In this study, a novel triple pore network model (T-PNM) is introduced which is composed of a single pore network model (PNM) coupled to fractures and micro-porosities. We use two stages of the watershed segmentation algorithm to extract the required data from semi-real micro-tomography images of porous material and build a structural network composed of three conductive elements: meso-pores, micro-pores, and fractures. Gas and liquid flow are simulated on the extracted networks and the calculated permeabilities are compared with dual pore network models (D-PNM) as well as the analytical solutions. It is found that the processes which are more sensitive to the surface features of material, should be simulated using a T-PNM that considers the effect of micro-porosities on overall process of flow in tight pores. We found that, for gas flow in tight pores where the close contact of gas with the surface of solid walls makes Knudsen diffusion and gas slippage significant, T-PNM provides more accurate solution compared to D-PNM. Within the tested range of operational conditions, we recorded between 10 and 50% relative error in gas permeabilities of carbonate porous rocks if micro-porosities are dismissed in the presence of fractures.

中文翻译：

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用于裂缝、微孔和中孔介质中气体流动模拟的三孔网络模型 (T-PNM)

在这项研究中，引入了一种新的三重孔隙网络模型 (T-PNM)，它由与裂缝和微孔隙度耦合的单孔隙网络模型 (PNM) 组成。我们使用分水岭分割算法的两个阶段从多孔材料的半真实显微断层扫描图像中提取所需的数据，并构建由三个导电元素组成的结构网络：中孔、微孔和裂缝。在提取的网络上模拟气体和液体流动，并将计算出的渗透率与双孔网络模型 (D-PNM) 以及解析解进行比较。发现对材料表面特征更敏感的过程应使用 T-PNM 进行模拟，该 T-PNM 考虑了微孔隙度对致密孔隙中流动的整体过程的影响。我们发现，对于气体在致密孔隙中的流动，气体与固体壁表面的紧密接触使得 Knudsen 扩散和气体滑移显着，与 D-PNM 相比，T-PNM 提供了更准确的解决方案。在测试的操作条件范围内，如果在存在裂缝的情况下消除微孔隙，我们记录到碳酸盐多孔岩石的气体渗透率的相对误差在 10% 到 50% 之间。