Yin Chenggang, Guan Wei, Hu Hengshan
College of Intelligent Manufacture, Taizhou University, Taizhou 317000, China.
Department of Astronautics and Mechanics, Harbin Institute of Technology, Harbin 150001, China.
Sensors (Basel). 2024 May 29;24(11):3514. doi: 10.3390/s24113514.
The streaming potential effect has a wide range of applications in geophysics. The core streaming potential experiment requires that there is no external circuit at both ends of the core, but a measurement circuit must be introduced to measure the voltage between both ends of the core which will cause an external circuit. In order to analyze the effect of measurement circuits on the streaming potential experiment, this paper proposes a core current source model, i.e., the core in the streaming potential experiment is regarded as a circuit composed of a current source whose output current is equal to the seepage current and the core resistance. By changing the resistance value of the external circuit, it is found that the seepage current is not affected by the external resistance but by the excitation pressure. Experiments on the streaming potential of 20 sandstone cores under distilled water, 0.01 mol/L, 0.02 mol/L, 0.05 mol/L, 0.1 mol/L, 0.2 mol/L, 0.4 mol/L, and 0.6 mol/L sodium chloride solutions revealed that the effect of the external circuit on the streaming potential signal increased with decreasing mineralization. For distilled water-saturated sandstone cores, the effect of the external circuit was about 2%.
流动电位效应在地球物理学中有广泛应用。岩芯流动电位实验要求岩芯两端无外部电路，但必须引入测量电路来测量岩芯两端的电压，这会导致外部电路的存在。为了分析测量电路对流动电位实验的影响，本文提出了一种岩芯电流源模型，即将流动电位实验中的岩芯视为一个由输出电流等于渗流电流的电流源和岩芯电阻组成的电路。通过改变外部电路的电阻值，发现渗流电流不受外部电阻影响，而是受激发压力影响。对20个砂岩岩芯在蒸馏水、0.01mol/L、0.02mol/L、0.05mol/L、0.1mol/L、0.2mol/L、0.4mol/L和0.6mol/L氯化钠溶液中的流动电位进行实验，结果表明，外部电路对流动电位信号的影响随着矿化度降低而增大。对于蒸馏水饱和的砂岩岩芯，外部电路的影响约为2%。
