Evidence of electrical anisotropy in limestone formations using the RMT technique
Evidence of electrical anisotropy in limestone formations using the RMT technique
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DOI：
10.1190/1.1778234
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发表时间：
2004-07
期刊：
影响因子：
3.3
通讯作者：
N. Linde;L. Pedersen
中科院分区：
文献类型：
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作者：
N. Linde;L. Pedersen
在抽水试验中，方位电阻率测量常常被用来补充水文信息或改善观测孔的位置。对称电极配置不能区分各向异性与横向变化或倾斜层，但非对称阵列(例如，偏移温纳阵列)可以区分各向异性。张量大地电磁法(RMT)是研究浅层地下电性各向异性的一种新方法。电磁和地磁传递函数提供有关数据维度的信息。这些传递函数也可以用来确定各向异性的方向。对于一维(1D)方位各向异性模型，可以对具有各向异性签名的数据进行反转。该方法比方位角电阻率法速度快，并用瑞典哥特兰岛上覆石灰岩的380米长的张量RMT资料(12.7-243 kHz)验证了该方法的优越性。数据具有明显的各向异性特征。
Azimuthal resistivity surveys are often applied to complement hydrological information or to improve the location of observation boreholes in pump tests. Symmetric electrode configurations cannot distinguish anisotropy from lateral changes or dipping layers, but asymmetric arrays (e.g., the offset Wenner array) can. Tensor radiomagnetotellurics (RMT) is presented as an alternative method in studies of electrical anisotropy in the shallow subsurface. The electromagnetic and geomagnetic transfer functions provide information about the dimensionality of the data. These transfer functions can also be used to find the directions of anisotropy. Data with an anisotropic signature can be inverted for a one‐dimensional (1D) azimuthal anisotropy model. The method is faster than the azimuthal resistivity method.A 380‐m‐long profile of tensor RMT data (12.7–243 kHz) from limestones that overlie shale on the island of Gotland, Sweden, is used to show the merits of the method. The data have a clear anisotropic signatur...