CSAMT法深部低阻分辨能力及方法研究  

Study of Resolution and Method of CSAMT for the Deep Low-Resistivity

作　　者：王艳[1] 林君[1] 周逢道[1] 张文秀[1] 

机构地区：[1]吉林大学仪器科学与电气工程学院,地球信息探测仪器教育部重点实验室,吉林长春130026

出　　处：《中国矿业大学学报》2009年第1期86-90,共5页Journal of China University of Mining & Technology

基　　金：国家自然科学基金项目(40074045);国家自然科学基金科学仪器专项(40727002)

摘　　要：基于大深度(2 000 m)3层H型模型,采用MATLAB模拟了可控源音频大地电磁法(CSAMT)中不同地质模型的电磁场响应和视电阻率曲线,根据曲线特征探讨了各地质参数对CSAMT法分辨能力的影响,研究了如何提高电磁场响应强度从而真正实现分辨深部低阻.结果表明:当覆盖层和低阻层电阻率比值大于2时可以分辨低阻,且分辨能力随覆盖层厚度的降低,低阻层厚度的增加及其电阻率的降低而增加;各地质模型均存在分辨低阻的最佳发射频率,且采用该频率作为最小发射频率进行勘探,可使电磁场幅值随该频率的1.5次幂增长,从而解决电场响应幅值微弱(nV),接收机难以分辨的问题.The controlled source audio frequency magnetotelluric（CSAMT） electromagnetic responses and apparent resistivity curves of different geologic models were simulated using a MATLAB software based on the 3-layer 2000 m depth H-type model. According to the curves characteristics, the effects of geologic parameters on CSAMT resolution were discussed, and the way how to improve the electromagnetic response was studied in order to resolve the low- resistivity layer actually. The results show that there exists an optimal transmitting frequency for each model. The low-resistivity layer can be resolved when the resistivity rate of overlay and low-resistivity layer is greater than 2. When the optimal frequency is adopted as the minimum transmitting frequency, the electromagnetic field value can be increased by 1.5 power of the frequency, which solved the problem that the electric response values are too weak （nV） to be resolved by the receiver.

关 键 词：CSAMT 深部 最佳发射频率 分辨能力 响应微弱 

分 类 号：P631[天文地球—地质矿产勘探]