Laboratory determination of the full electrical resistivity tensor of heterogeneous carbonate rocks at elevated pressures
Laboratory determination of the full electrical resistivity tensor of heterogeneous carbonate rocks at elevated pressures
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DOI：
10.1111/j.1365-2478.2012.01113.x
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发表时间：
2013-03
影响因子：
2.6
通讯作者：
L. North;A. Best;J. Sothcott;L. MacGregor
中科院分区：
文献类型：
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作者：
L. North;A. Best;J. Sothcott;L. MacGregor
我们描述了一种测量系统，该系统能够使用电法在升高的、具有地质代表性的压力下确定岩心样品的全电阻率张量。它适用于非均质岩石，在不受样品选择和非均质影响的情况下难以测量张电阻率。我们利用合成数据和碳酸盐岩岩心样品的测量证明了该系统的有效性。该仪器采用计算机控制的16个电极阵列，向直径5厘米的圆柱形样品注入电流并测量其边界电压。一种计算效率高的有限元算法用于从测量电压中检索全电阻率张量。该算法使用各向同性有限元代码来计算任意几何形状样本的各向异性解。侏罗纪石灰岩和三叠纪白云岩样品的初步结果显示，厘米尺度的非均质性和显著的体积各向异性与X射线计算机断层扫描图像中观察到的岩石结构一致。
We describe a measurement system capable of determining the full resistivity tensor of core samples at elevated, geologically representative, pressures using a galvanic method. It is suitable for heterogeneous rocks where it is difficult to measure tensorial resistivity without bias from sample selection and heterogeneity. We demonstrate the efficacy of the system using both synthetic data and measurements on carbonate rock core samples. The apparatus employs a computer controlled array of 16 electrodes to inject current into, and measure boundary voltages on, a 5 cm diameter cylindrical sample. A computationally efficient FE algorithm is used to retrieve the full resistivity tensor from the measured voltages. The algorithm uses isotropic Finite Element code to calculate anisotropic solutions for samples of arbitrary geometry. Initial results from Jurassic limestone and Triassic dolomite samples, reveal cm‐scale heterogeneity and significant bulk anisotropy consistent with rock fabric observed in X‐ray Computed Tomography scan images.