This study focuses on direct numerical simulation of imbibition, displacement of the non-wetting phase by the wetting phase, through water-wet carbonate rocks. We simulate multiphase flow in a limestone and compare our results with high-resolution synchrotron X-ray images of displacement previously published in the literature by Singh et al. (Sci Rep 7:5192, 2017). We use the results to interpret the observed displacement events that cannot be described using conventional metrics such as pore-to-throat aspect ratio. We show that the complex geometry of porous media can dictate a curvature balance that prevents snap-off from happening in spite of favourable large aspect ratios. We also show that pinned fluid-fluid-solid contact lines can lead to snap-off of small ganglia on pore walls; we propose that this pinning is caused by sub-resolution roughness on scales of less than a micron. Our numerical results show that even in water-wet porous media, we need to allow pinned contacts in place to reproduce experimental results.

本研究侧重于直接数值模拟渗吸，非湿相被湿相置换，通过水湿碳酸盐岩。我们模拟石灰岩中的多相流，并将我们的结果与 Singh 等人先前在文献中发表的高分辨率同步加速器 X 射线位移图像进行比较。(Sci Rep 7:5192, 2017)。我们使用结果来解释观察到的位移事件，这些事件无法使用常规指标（例如孔喉纵横比）进行描述。我们表明，多孔介质的复杂几何形状可以决定曲率平衡，尽管具有有利的大纵横比，但仍可防止发生折断。我们还表明，固定的流体 - 流体 - 固体接触线会导致孔壁上的小神经节折断；我们认为这种钉扎是由小于微米尺度的亚分辨率粗糙度引起的。我们的数值结果表明，即使在水润湿的多孔介质中，我们也需要允许固定接触到位以重现实验结果。