Capacitive conductivity logging and electrical stratigraphy in a high-resistivity aquifer, Boise Hydrogeophysical Research Site
Capacitive conductivity logging and electrical stratigraphy in a high-resistivity aquifer, Boise Hydrogeophysical Research Site
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高电阻率含水层中的电容电导率测井和电地层学，博伊西水文地球物理研究站
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发表时间：
2009
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影响因子：
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通讯作者：
M. Knoll
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作者：
J. Mwenifumbo;W. Barrash;M. Knoll
我们在博伊西水文地球物理研究基地BHRS的一个浅的、非承压含水层中测试了一个原型电容-电导率钻孔工具，该含水层含有粗的、松散的沉积物和极低电导率的水。检查这样的高电阻率系统为电容-电导率测井仪提供了一个很好的测试，因为已知在高电阻率系统中有效性有限的传统感应-电导率测井仪在BHRS上不能产生有表现力的测井曲线。电容-电导率测井仪表现出高度可重复性、低噪声特性，但在地层的低电导率部分与感应测井仪相关性较差，在该部分感应测井仪相对无响应。对电容-电导率测井曲线的奇异谱分析表明，BHRS的构造-孔隙度测井曲线在纵向上具有相似的长度尺度，同时，在电容-电导率测井曲线中，孔隙度测井曲线所识别的主要地层单元也很明显。然而，在一个主要地层单元的上部，一个以前未被认识到的细分部分可以被一致地确定为相对低传导性的主体，即，上覆地层单元和电导率相对较高的下部之间的电地层单元-尽管相邻单元的孔隙度和岩性相似。电容-电导率测井仪的高重复性、高分辨率和宽动态范围在这里被证明可以扩展到高电阻率、未固结沉积物的测井。
We tested a prototype capacitive-conductivity borehole tool in a shallow, unconfined aquifer with coarse, unconsolidated sediments and very-low-conductivity water at the Boise Hydrogeophysical Research Site BHRS. Examining suchahigh-resistivitysystemprovidesagoodtestforthecapacitive-conductivity tool because the conventional induction-conductivity tool known to have limited effectiveness in high-resistivity systems did not generate expressive well logs at the BHRS. The capacitive-conductivity tool demonstrated highly repeatable, low-noise behavior but poor correlation with the induction tool in the lower-conductivity portions of the stratigraphy where the induction tool was relatively unresponsive. Singular spectrum analysis of capacitive-conductivity logs reveals similar vertical-length scales ofstructurestoporositylogsattheBHRS.Also,majorstratigraphic units identified with porosity logs are evident in the capacitive-conductivity logs. However, a previously unrecognized subdivision in the upper portion of one of the major stratigraphicunitscanbeidentifiedconsistentlyasarelatively low-conductivity body i.e., an electrostratigraphic unit between the overlying stratigraphic unit and the relatively high-conductivity lower portion — despite similar porosity and lithology in adjacent units. The high repeatability and resolutionandthewidedynamicrangeofthecapacitive-conductivity tool are demonstrated here to extend to high-resistivity,unconsolidatedsedimentaryaquiferenvironments.