Effect of pore geometry and interfacial tension on water-oil displacement efficiency in oil-wet microfluidic porous media analogs
Effect of pore geometry and interfacial tension on water-oil displacement efficiency in oil-wet microfluidic porous media analogs
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DOI：
10.1063/1.4894071
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发表时间：
2014-09
影响因子：
4.6
通讯作者：
W. Xu;J. T. Ok;F. Xiao;K. Neeves;Xiaolong Yin
中科院分区：
文献类型：
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作者：
W. Xu;J. T. Ok;F. Xiao;K. Neeves;Xiaolong Yin
采用亲油聚二甲基硅氧烷（PDMS）微流控多孔介质模拟物，研究了恒定压力梯度驱动下孔隙几何形状和界面张力对水驱油效率的影响。这种情况与非均质地层注水时旁路油湿层的排油情况有关。相似物的孔隙度和渗透率分别为0.19和0.133 ~ 0.268 × 10−12 m2；每个模拟物的长度为30mm，宽度为3mm，较长的尺寸与气流方向一致。孔隙几何结构包括三个基于Voronoi图的随机网络和八个三角形、正方形、菱形和六边形的周期性网络。我们发现，在随机网络中，孔隙宽度分布和孔洞（大空腔）都降低了置换效率，在周期性网络中，置换效率随着配位数的增加而降低，均匀微流控通道宽度的随机网络与六边形网络的置换效率相似。当存在溶洞时，位移受溶洞充填顺序的控制，溶洞间结构的影响较小。表面活性剂（0.5 wt. %乙氧基醇）通过增加毛细管数量和抑制毛细管不稳定性来提高所有几何形状的驱油效率。
Using oil-wet polydimethylsiloxane (PDMS) microfluidic porous media analogs, we studied the effect of pore geometry and interfacial tension on water-oil displacement efficiency driven by a constant pressure gradient. This situation is relevant to the drainage of oil from a bypassed oil-wet zone during water flooding in a heterogeneous formation. The porosity and permeability of analogs are 0.19 and 0.133–0.268 × 10−12 m2, respectively; each analog is 30 mm in length and 3 mm in width, with the longer dimension aligned with the flow direction. The pore geometries include three random networks based on Voronoi diagrams and eight periodic networks of triangles, squares, diamonds, and hexagons. We found that among random networks both pore width distribution and vugs (large cavities) decreased the displacement efficiency, among the periodic networks the displacement efficiency decreased with increasing coordination number, and the random network with uniform microfluidic channel width was similar to the hexagon network in the displacement efficiency. When vugs were present, displacement was controlled by the sequence of vug-filling and the structure of inter-vug texture was less relevant. Surfactant (0.5 wt. % ethoxylated alcohol) increased the displacement efficiency in all geometries by increasing the capillary number and suppressing the capillary instability.