Abstract The appearing of clay (conductive) layer(s) at different depths of the lithological succession has been widely observed in the Upper Egypt district. This phenomenon has dramatic effects on the resultant depth of investigation of any geoelectrical survey of such environment. Study the effect of such layers on estimating Depth of Investigation (DOI) is the main goal of this article. Because the reliability of the Two Dimensional Electrical Resistivity Imaging (2DERI) models alters rapidly with changing conductive layers depths as well as noisy data ratios, an accurate estimation of DOI is critical to help geophysists determining the optimum hydrogeophysical survey design in clayey environments. The modified depth of investigation method which mainly depends on the statistical method is applied to estimate the DOI. In this article, the study is based on synthetic and field data sets. Wenner (W), Wenner Schlumberger (WSC) and Dipole-Dipole (DD) electrode arrays were chosen to clarify which electrode gives larger DOI in the conceptual models (presence conductive layer at 0, 50 and 100 m depths) from the ground surface. Moreover, this study includes a test for the effect of adding 10% noise to synthetic data sets on DOI estimation. It is well known that Wenner array better matches with layer-like targets, DD with 3D horizontally limited ones. Based on these results, there is a relationship between DOI and depth of the conductive layer [larger DOI is recorded when conductive layer exists at deeper depths and vice versa]. This could be related to the existence of a conductive layer in the lithology succession that can limit the current to flow vertically and subsequently, affects DOI estimation. 2D ERI field data from West Bani Mazar, El Minia is used to support the supposed first conceptual model on DOI estimation.

中文翻译：

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导电层对二维地电成像中调查深度估计的影响：以埃及 El Minia 的 West Bani Mazar 为例

摘要 在上埃及地区广泛观察到在岩性序列不同深度处出现粘土（导电）层。这种现象对此类环境的任何地电勘测的最终勘测深度具有显着影响。研究此类图层对估计调查深度 (DOI) 的影响是本文的主要目标。由于二维电阻率成像 (2DERI) 模型的可靠性随着导电层深度的变化以及噪声数据比率的变化而迅速变化，因此准确估计 DOI 对于帮助地球物理学家确定粘土环境中的最佳水文地球物理勘测设计至关重要。主要依靠统计方法的改进的调查深度方法被应用于估计DOI。在本文中，该研究基于合成和实地数据集。选择 Wenner (W)、Wenner Schlumberger (WSC) 和 Dipole-Dipole (DD) 电极阵列来阐明在概念模型中哪个电极提供更大的 DOI（在 0、50 和 100 m 深度存在导电层）离地表。此外，这项研究还包括对合成数据集添加 10% 噪声对 DOI 估计的影响的测试。众所周知，Wenner 阵列更好地匹配层状目标，DD 与 3D 水平有限的目标匹配。基于这些结果，DOI 和导电层的深度之间存在关系[当导电层存在于更深的深度时记录更大的 DOI，反之亦然]。这可能与岩性序列中存在导电层有关，该导电层可以限制电流垂直和随后流动，影响 DOI 估计。来自 El Minia 的 West Bani Mazar 的 2D ERI 现场数据用于支持假设的第一个 DOI 估计概念模型。