Worldwide, soil contamination due to industrial activities is a major issue. One method for remediation of contaminated sites is in situ chemical oxidation, where an oxidizing agent is injected into the contaminated soil. Normally, monitoring wells are established in the remediation area for tracking the oxidizing agent. However, wells only provide point information of the injectant spread. This issue can be addressed using cross‐borehole resistivity and induced polarization tomography, by mapping the electrical properties in the entire remediation volume and by deriving, through petrophysical relations, the hydraulic properties of the medium. Here we present a proof‐of‐concept study, performed over one year as part of a larger remediation project, where resistivity and time‐domain induced polarization data were acquired among 10 boreholes, before and after two rounds of injection of oxidizing agents. The time‐lapse resistivity models, obtained through a focusing inversion scheme that favours compact time‐lapse changes, clearly show the oxidizing agent spread as highly conductive anomalies and confirmed by water conductivity measurements in boreholes. The time‐lapse inversions also show spatial variability in the injectant spread, with some areas not reached. The induced polarization data quality decreased significantly just after the injection rounds, because of the decrease in resistivity and induced polarization signal level, so that induced polarization time‐lapse inversions were not feasible. However, the induced polarization data were used for background characterization and to estimate permeability. In particular, there is a good match between the imaged low‐permeability zones and the areas in which the injectant did not spread, identified by the time‐lapse resistivity inversions. Furthermore, geological samples confirm the presence of fine‐grained sediments in the estimated low‐permeability zones. While time‐lapse resistivity tomography may be used for documenting the injectant spread, induced polarization permeability estimates prior to injection can be used to better tailor the remediation in terms of dimension and location of injection filters.

中文翻译：

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跨孔地电时延监测通过感应极化原位化学氧化和渗透率估算

在世界范围内，由于工业活动造成的土壤污染是一个主要问题。原位修复污染场地的一种方法是化学氧化，将氧化剂注入污染的土壤中。通常，在修复区中建立监测井以跟踪氧化剂。但是，孔仅提供注入剂扩散的点信息。可以使用跨孔电阻率和感应极化层析成像技术解决此问题，方法是在整个修复体积中绘制电气特性，并通过岩石物理关系推导介质的水力特性。在这里，我们提出了一项概念验证研究，该研究是作为一个大型修复项目的一部分进行的，为期一年，其中在注入两轮氧化剂前后，在10个钻孔中采集了电阻率和时域感应极化数据。延时电阻率模型 通过有利于紧凑的时移变化的聚焦反演方案获得的结果清楚地表明，氧化剂以高导电异常的形式传播，并通过钻孔中的水电导率测量得到证实。时移反演还显示了注入剂扩散的空间变异性，某些区域未达到。由于电阻率和极化信号电平的降低，在注入回合之后，极化极化数据的质量就显着下降，因此极化极化延时反演是不可行的。但是，感应的极化数据用于背景表征和估计磁导率。特别是，在成像的低渗透率区域和注入剂未扩散的区域之间存在良好的匹配，通过延时电阻率反演确定。此外，地质样品证实了估计的低渗透带中存在细粒沉积物。尽管可以使用延时电阻率层析成像技术来记录注入剂的扩散情况，但在注入之前可以使用感应极化渗透率估算值来更好地调整注入过滤器的尺寸和位置。