1. Key Laboratory of Mineral Resources, Chinese Academy of Sciences, Beijing 100029;
2. Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029;
3. Key Laboratory of Coal Resources Exploration and comprehensive Utilization, Ministry of land and resource, Xi'an 710054
Overcoming the shielding effect of conductor covered layer and realizing the effective detection of low resistivity layer underground 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 comparison with a grounded electric source frequency device-(CSAMT),which is generally used nowadays.In this paper,the response characteristics 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.
[1] 李貅.瞬变电磁测深的理论与应用[M].西安:陕西科学技术出版社,2002.[2] Newman G A.Deep transient electromagnetic soundings with a grounded source over near-surface conductors[J].Geophysical Journal International,1989,98(3):587-601.[3] 严良俊,胡文宝.长偏移距瞬变电磁测深的全区视电阻率求取及快速反演方法[J].石油地球物理勘探,1999,34(5):532-538.[4] 周楠楠,薛国强,李海.回线源瞬变电磁水平分量对薄层的分辨能力[J].地球物理学进展,2014,29(5):2347-2355.[5] 薛国强,邓湘.瞬变电磁法对薄层的探测能力[J].石油地球物理勘探,2008,42(6):709-713.[6] 牛之琏.瞬变电磁测深法对导电层的探测能力[J].地质与勘探,1992,28(7):37-40.[7] 薛国强,李貅,底青云.瞬变电磁法理论与应用研究进展[J].地球物理学进展,2007,22(4):1195-1200.[8] 王战军,朱自强,李建慧,等.瞬变电磁法对低阻薄层的分辨能力研究[J].物探化探计算技术,2012,34(6):646-651.[9] 武军杰,杨毅,张杰,等.TEM对于深部低阻层的分辨能力模拟分析[J].物探化探计算技术,2014,36(5):547-554.[10] 殷长春.可控源音频磁大地电流法一维正演及精度评价[J].长春地质学院学报,1994,24(4):438-443.[11] 龚飞,底青云.某煤矿典型CSAMT法视电阻率曲线的一维模拟[J].地球物理学进展,2004,19(3):631-634.[12] 安志国,底青云.CSAMT法对低阻薄层结构分辨能力的探讨[J].地震地磁观测与研究,2006,27(2):32-38.[13] 汤井田,周聪,邓晓红.CSAMT视电阻率曲线对水平层状大地的识别与分辨[J].地质与勘探,2010,46(6):1079-1086.[14] 王若,殷长春,王妙月,等.CSAMT法一维层状介质灵敏度分析[J].地球物理学进展,2014,29(3):1284-1291.[15] 薛国强,陈卫营,周楠楠,等.接地源瞬变电磁短偏移深部探测技术[J].地球物理学报,2013,56(1):255-261.[16] Zhou N N,Xue G Q,Chen W,et al.Large-depth hydrogeological detection in the North China-type coalfield through short-offset grounded-wire TEM[J].Environmental Earth Sciences,2015:1-12.[17] Chen W Y,Xue G Q,Muhammad Y K,et al.Application of Short-Offset TEM (SOTEM) technique in mapping water-enriched zones of coal stratum,an example from east China[J].Pure and Applied Geophysics,2015,172(6):1643-1651.[18] 陈卫营,薛国强.电性源瞬变电磁对薄层的探测能力[J].物探与化探,2015,39(4):775-779.[19] 曹昌祺.水平电偶极变频测深的低频特性和对高阻层的穿透问题[J].地球物理学报,1982,25(6):516-537.[20] 汤井田,周聪,肖晓.复杂介质条件下CSAMT最小发收距的选择[J].中国有色金属学报,2013,23(6):1681-1693.[21] 王显祥,底青云,许诚.CSAMT的多偶极子源特征与张量测量[J].地球物理学报,2014,57(2):651-661.[22] 陈明生,闫述.CSAMT勘探中场区,记录规则,阴影及场源复印效应的解析研究[J].地球物理学报,2005,48(4):951-958.[23] 米萨克N纳比吉安.勘查地球物理:电磁法(第一卷)[M].赵经祥,王艳君,译.北京:地质出版社,1992.[24] 牛之琏.时间域电磁法原理[M].长沙:中南工业大学出版社,1992.
