Relationships among air-water interfacial area, capillary pressure, and water saturation for a sandy porous medium
Relationships among air-water interfacial area, capillary pressure, and water saturation for a sandy porous medium
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DOI：
10.1029/2005wr004058
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发表时间：
2006-03-14
影响因子：
5.4
通讯作者：
Costanza-Robinson, MS
中科院分区：
文献类型：
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作者：
Brusseau, ML;Peng, S;Costanza-Robinson, MS
在砂质天然多孔介质中，研究了气-水界面面积、毛细压力和含水饱和度之间的关系。空气-水界面面积作为水饱和度的函数测量使用两种方法，气相分配示踪测试和同步加速器x射线微断层扫描。示踪剂测试方法提供了有效总（毛细血管和膜）界面面积的测量，而显微断层扫描可用于确定毛细血管相关和总面积（后者是本研究的重点）。两种方法测定的气-水界面面积随着含水饱和度的降低而不断增大。用示踪试验方法测得的面积明显大于显微断层扫描法测得的面积。示踪剂测试法测得的最大值接近于N-2/ bet法测得的固体比表面积，而微层析成像法测得的最大值接近于光滑球法计算的固体比表面积。将界面面积-饱和度数据与排水实验所得毛细压力-饱和度数据相结合，考察了气-水界面总面积与毛细压力的关系。观察到空气-水界面面积随着毛管压力的增加而单调增加，然后在与剩余水饱和度相关的区域对应的值处趋于平稳。这些结果与先前报道的基于理论和计算的总非润湿-润湿界面面积与毛细压力之间的函数关系的分析一致。
[1] The relationships among air-water interfacial area, capillary pressure, and water saturation were investigated for a sandy, natural porous medium. Air-water interfacial areas as a function of water saturation were measured using two methods, gas phase partitioning tracer tests and synchrotron X-ray microtomography. The tracer test method provides a measure of effective total ( capillary and film) interfacial area, whereas microtomography can be used to determine both capillary-associated and total areas ( the latter is the focus of this study). Air-water interfacial areas determined with both methods increased continuously with decreasing water saturation. The areas measured with the tracer test method were significantly larger than those obtained from microtomography. The maximum values measured with the tracer test method approached the N-2/BET-measured specific solid surface area, whereas the maximum values measured by microtomography approached the smooth-sphere-calculated specific solid surface area. The interfacial area-saturation data were combined with capillary pressure-saturation data obtained from water drainage experiments to examine the relationship between total air-water interfacial area and capillary pressure. Air-water interfacial area was observed to increase monotonically with increasing capillary pressure and then to plateau at values that correspond to areas associated with residual water saturation. These results are consistent with previously reported theoretically and computationally based analyses of functional relationships between total nonwetting-wetting interfacial area and capillary pressure.