Distinguishing capability of SOTEM and CSAMT for low resistivity layer
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摘要: 克服低阻覆盖层的屏蔽以及实现对地下低阻层的有效探测,一直是勘探电磁法面临的重要问题. 电性源短偏移瞬变电磁法( SOTEM)采用近源观测,受到越来越多关注. 为了分析SOTEM的探测能力,开展了与目前普遍使用的电性源频率域装置——可控源音频大地电磁法( CSAMT)的对比性研究. 首先分析了SOTEM 和CSAMT在一维层状介质下的理论响应特征,然后,分别设计了不同情况下低阻覆盖层和地下低阻夹层两组地电模型,通过计算相对异常误差,分析了二者的探测能力. 研究结果表明:SOTEM比CSAMT对低阻覆盖层更加敏感,对低阻夹层的探测能力更强,更有利于探测地下导电夹层.
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关键词:
- 电性源短偏移瞬变电磁法(SOTEM) /
- 可控源音频大地电磁法(CSAMT) /
- 低阻层 /
- 分辨能力
Abstract: Overcoming the shielding effect of conductor covered layer and realizing the effective detection of low resistivity layer under-ground constitute an important problem in electromagnetic exploration.Short offset transient electromagnetic (SOTEM) is receiving more and more attention because of its near source observation method.In order to analyze its detection capability,the authors made a compar-ison with a grounded electric source frequency device-(CSAMT),which is generally used nowadays.In this paper,the response charac-teristics of SOTEM and CSAMT in 1-D layered media are studied.In addition,two groups of electric models of low resistivity covered layer and low resistivity interbbed with different electrical characteristics are designed.Then detection capability is comparatively studied by calculating relative anomaly error. It is concluded by analysis that SOTEM is more sensitive to low resistivity covered layer than CSAMT and hence it is more favorable for detecting underground conductor layer.-
Key words:
- SOTEM /
- CSAMT /
- low resistivity layer /
- distinguishing capability
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