The electrical field in a borehole with a casing
The electrical field in a borehole with a casing
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DOI：
10.1190/1.1442769
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发表时间：
1990
期刊：
影响因子：
3.3
通讯作者：
A. Kaufman
中科院分区：
文献类型：
--
作者：
A. Kaufman
套管存在时井眼轴线上的电场可分为近区、中区和远区。在中间带内，通过确定电位的二阶导数，可以确定地层电阻率。在套管外部，在离井眼很远的距离处，电场具有径向方向，该径向方向在该方向上提供足够的调查深度。测量需要了解套管电导。传输线理论的应用是基于这样的事实，即地层中的电场在中间区域内是径向的，从而得出这样的结论：这种测量的垂直分辨率将仅取决于估计电势的二阶导数所需的电极的间距。
The electric field on the borehole axis in the presence of a casing can be divided into three zones: the near, intermediate, and far zones. Within the intermediate zone, determination of the second derivative of the potential allows me to define the formation resistivity. Outside the casing, the electric field, at large distances from the borehole, has a radial direction that provides a sufficient depth of investigation in this direction. The measurement requires knowledge of the casing conductance. Application of transmission line theory is based on the fact that the electric field in the formation is radial within the intermediate zone, resulting in the conclusion that the vertical resolution of such a measurement would depend only upon the spacing of the electrodes required to estimate the second derivative of the potential.