Impact of Wettability and Gravity on Fluid Displacement and Trapping in Representative 2D Micromodels of Porous Media (2D Sand Analogs)
Impact of Wettability and Gravity on Fluid Displacement and Trapping in Representative 2D Micromodels of Porous Media (2D Sand Analogs)
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DOI：
10.1029/2021wr029908
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发表时间：
2021-10-01
影响因子：
5.4
通讯作者：
Geistlinger, Helmut
中科院分区：
文献类型：
--
作者：
Golmohammadi, Saeed;Ding, Yi;Geistlinger, Helmut
重力和润湿性对位移和捕获的综合影响以前没有在现实的2D多孔介质中进行过实验研究。在这里，我们报告的第一次使用的代表性的二维微观模型，准确地再现特征的几何，形态和拓扑特性的三维填砂。我们使用这些有代表性的微观模型，比较润湿性的位移前形态和捕获过程中使用选定的流体对毛细管数在10（-6）和10（-5）之间的依赖。研究的接触角范围为30度（正常吸胀）至150度（强排水）。重力的影响是戏剧性的：在水平流动的情况下，只有一个手指的发展，这是纵向位移总是有利的，而重力创建一个更紧凑的位移前沿与广泛的横向延伸，这种横向运动创建环路，导致旁路捕获。结果，捕集效率从7%提高到29%。我们观察到的集群大小分布的普遍缩放表明，我们的微观模型是统计上的代表性。得到了2.05的普适二维标度指数，误差小于5%。我们通过荧光显微镜获得的实验结果显示（a）在θ = 51度处弱吸胀的前体角流，即高于α（c）= 45度的临界接触角（Zhao等人，2016，），和（B）在中性润湿性条件下，即在θ（c）接近90度时，从角流到全管道流的新润湿转变;和（c）在该第二临界接触角以上，即在强排水条件下，我们再次观察到角流（具体地，芯-环形流）。
The combined effects of gravitational forces and wettability on displacement and trapping have not previously been investigated experimentally in realistic 2D porous media. Here we report the first use of representative 2D micromodels that accurately reproduce characteristic geometric, morphological, and topological properties of 3D sand packs. We use these representative micromodels to compare the wettability dependence of displacement front morphology and trapping processes using selected fluid pairs at capillary numbers between 10(-6) and 10(-5). The contact angles studied ranged from 30 degrees (normal imbibition) to 150 degrees (strong drainage). The impact of gravity was dramatic: In the horizontal flow case, only one finger developed, that is longitudinal displacement was always favored, whereas gravity created a more compact displacement front with broad lateral extension, and this lateral movement created loops, leading to by-pass trapping. As a result, the trapping efficiency rose from 7% to 29%. We observed universal scaling of the cluster size distribution demonstrating that our micromodels are statistically representative. The universal 2D-scaling exponent of 2.05 was obtained with an acceptable error smaller than 5%. Our experimental results obtained by fluorescence microscopy showed (a) precursor corner flow for weak imbibition at theta = 51 degrees, that is above the critical contact angle of alpha(c) = 45 degrees (Zhao et al., 2016, ), and (b) a new wetting transition from corner flow to full duct flow under neutral wettability conditions, that is at theta(c) approximate to 90 degrees; and (c) above this second critical contact angle, that is under strong drainage conditions, we again observed corner flow (specifically, core-annular flow).