Streaming potential in porous media 1. Theory of the zeta potential
Streaming potential in porous media 1. Theory of the zeta potential
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DOI：
10.1029/1999jb900089
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发表时间：
1999-09-10
影响因子：
3.9
通讯作者：
Glover, PWJ
中科院分区：
文献类型：
--
作者：
Revil, A;Pezard, PA;Glover, PWJ
动电现象是流体饱和多孔材料的多种电性能的原因。这些现象的地球物理应用可能包括使用流动势来绘制地下流体流动图、研究地热区的热液活动以及地震预测和火山活动预测等。电动现象的关键参数是 zeta 电位，它大致代表矿物/水界面处的电位。我们考虑以二氧化硅为主的多孔材料，填充二元对称 1:1 电解质（例如 NaCl）。当与这种电解质接触时，二氧化硅/水界面通过化学反应获得过量的电荷。从这些化学反应开始，我们推导出 zeta 电位和比表面电导的解析方程。这些方程可用于预测这些参数随孔隙流体盐度、温度和pH（pH范围6-8）的变化。这些方程的输入参数分为两类：(1) 矿物/流体相互作用地球化学（包括矿物表面位点密度和矿物/流体反应的表面平衡常数），以及 (2) 孔隙流体 pH 值、盐度和温度。 Zeta 电位随着温度和 pH 值的增加而增加，并随着盐度的增加而减少。所提出的模型与现有的实验数据一致。配套论文探讨了该模型在多孔介质中由流体流动产生的电势的应用。
Electrokinetic phenomena are responsible for several electrical properties of fluid-saturated porous materials. Geophysical applications of these phenomena could include the use of streaming potentials for mapping subsurface fluid flow, the study of hydrothermal activity of geothermal areas, and in the context of earthquake prediction and volcanic activity forecasting, for example. The key parameter of electrokinetic phenomena is the zeta potential, which represents roughly the electrical potential at the mineral/water interface. We consider silica-dominated porous materials filled with a binary symmetric 1:1 electrolyte such as NaCl. When in contact with this electrolyte, the silica/water interface gets an excess of charge through chemical reactions. Starting with these chemical reactions, we derive analytical equations for the zeta potential End the specific surface conductance. These equations can be used to predict the variations of these parameters with the pore fluid salinity, temperature, and pH (within a pH range of 6-8). The input parameters to these equations fall into two categories: (1) mineral/fluid interaction geochemistry (including mineral surface site density and surface equilibrium constants of mineral/fluid reactions), and (2) pore fluid pH, salinity, and temperature. The zeta potential is shown to increase with increasing temperature and pH and to decrease with increasing salinity. The proposed model is in agreement with available experimental data. The application of this model to electric potentials generated in porous media by fluid flow is explored in the companion paper.