Experimental measurements of the streaming potential and seismoelectric conversion in Berea sandstone
Experimental measurements of the streaming potential and seismoelectric conversion in Berea sandstone
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DOI：
10.1111/j.1365-2478.2012.01110.x
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发表时间：
2013-05
影响因子：
2.6
通讯作者：
Zhenya Zhu;M. Nafi Toksöz
中科院分区：
文献类型：
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作者：
Zhenya Zhu;M. Nafi Toksöz
通过多孔介质的流势是由固体和流体之间的双电层引起的流体流动引起的。当声波通过多孔介质传播时，波压在固体和流体之间产生相对运动。流体中移动的电荷引起电场和震电转换。为了研究同一岩样中的流体电位和震电转换，我们对不同电导率NaCl溶液饱和的Berea砂岩进行了测量。我们测量了圆柱形样品在不同电导率和不同压力下的NaCl溶液中的电压（流电位），以确定直流耦合系数。我们还测量了声波在不同频率和溶液电导率下对伯里亚砂岩板产生的地震电信号。声波压力用标准水听器（br<s:1> el & 8103）在不同频率（15-120 kHz）下进行校准。我们计算了不同电导率溶液饱和样品在直流和高频下的震电转换的定量耦合系数。以电导率为0.32 mS/m的NaCl溶液饱和Berea砂岩样品为例，15 kHz时直流耦合系数为0.024 μV/Pa，震电耦合系数为0.019 μV/Pa。震电耦合系数是设计震电工具的重要参数。在100hz到15khz的频率范围内，需要进行更多的震电耦合系数的实验测量。
The streaming potential across a porous medium is induced by a fluid flow due to an electric double layer between a solid and a fluid. When an acoustic wave propagates through a porous medium, the wave pressure generates a relative movement between the solid and the fluid. The moving charge in the fluid induces an electric field and seismoelectric conversion. In order to investigate the streaming potential and the seismoelectric conversion in the same rock sample, we conduct measurements with Berea sandstone saturated by NaCl solutions with different conductivities. We measure the electric voltage (streaming potential) across a cylindrical sample in NaCl solutions with different conductivities and under different pressures to determine the DC coupling coefficients. We also measure the seismoelectric signals induced by acoustic waves with a Berea sandstone plate at different frequencies and solution conductivities. The pressures of the acoustic waves are calibrated with a standard hydrophone (Brüel & 8103) at different frequencies (15–120 kHz). We calculate the quantitative coupling coefficients of the seismoelectric conversion at DC and at high frequencies with samples saturated by solutions with different conductivities. When the Berea sandstone sample is saturated by the NaCl solution with 0.32 mS/m in conductivity, for example, the DC and seismoelectric coupling coefficients at 15 kHz are 0.024 μV/Pa and 0.019 μV/Pa, respectively. The seismoelectric coupling coefficient is an important and helpful parameter for designing a seismoelectric tool. More experimental measurements of seismoelectric coupling coefficients in the frequency range of 100 Hz to 15 kHz are needed in the future.