Hysteresis in the electrical resistivity of partially saturated sandstones
Hysteresis in the electrical resistivity of partially saturated sandstones
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DOI：
10.1190/1.1443028
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发表时间：
1991-12
期刊：
影响因子：
3.3
通讯作者：
R. Knight
中科院分区：
文献类型：
--
作者：
R. Knight
对在吸吸（增加 Sw）和排水（减少 Sw）过程中收集的三个砂岩样品的电阻率进行的实验室测量表明，在大部分饱和范围内，电阻率存在明显的滞后现象。电阻率的变化可能与饱和度历史变化引起的孔隙尺度流体分布的变化有关。滞后的形式使得在吸吸过程中测得的电阻率始终小于在相同饱和度下在排水过程中测得的电阻率。这可以归因于部分饱和样品中空气/水界面处存在传导；与吸入过程相关的流体几何形状增强了这种效果。这项研究的结果表明，在解释非饱和带数据时，应考虑地球物理数据对饱和历史的依赖性。
Laboratory measurements of the resistivity of three sandstone samples collected during imbibition (increasing Sw) and drainage (decreasing Sw) show pronounced hysteresis in resistivity throughout much of the saturation range. The variation in resistivity can be related to changes in pore-scale fluid distribution caused by changes in saturation history. The form of the hysteresis is such that resistivity measured during imbibition is consistently less than that measured, at the same saturation, during drainage. This can be attributed to the presence of conduction at the air/ water interface in partially saturated samples; an effect that is enhanced by fluid geometries associated with the imbibition process. The results of this study suggest that the dependence of geophysical data on saturation history should be considered when interpreting data from the unsaturated zone.