摘要
本文以实例结合数值模拟说明CSAMT中非平面波效应对资料解释的重要影响。实际数据测量于河南卢氏县,在同一条测线测量,发射源长度1.3 km,收发距离分别为4.5 km和7 km。通过对数据进行必要的校正后进行了光滑模型反演,为了对比反演结果,整个处理过程的参数都保持一致。反演的电阻率断面显示,两种收发距离反演的电阻率断面其异常形态基本一致;但在电阻率的数值上,4.5 km的收发距离反演的电阻率较7 km的大。分析发现上述现象主要是源的非平面波效应造成的,并通过三维正演数值模拟得到了验证。由于在有限收发距离时,计算卡尼亚视电阻率靠近源受非平面波效应影响偏大,远离源后,该视电阻率趋于平面波视电阻率。因此,为了采用目前的可控源音频大地电磁测深解释理论,要求收发距离尽可能大。否则,必须采用带源效应的真正可控源电磁反演技术完成数据分析。
In this paper,we illustrate the important influence of non-plane wave effect in controlled source audio frequency magnetotelluric( CSAMT)survey combining the numerical simulation of a real example. The data was measured in the Lushi county,Henan Province. In the same measuring line,the length of source was 1. 3km and the two receiving distances were 4. 5 km and 7 km,respectively. After the necessary correction on the data,we performed the smooth model inversion. For comparing the inversion results,all the processing parameters were consistent. The resistivity section shows the two receiving distances share the basically same morphology,while compared with the receiving distance 7. 5 km,the apparent resistivity of 4. 5 km is larger. Through the analysis we found the phenomena above is owing to the effect of non-plane waves,and verified it with 3-D forward numerical modeling.Because of the limited receiving distance,the influence on the Cagniard apparent resistivity is larger when close to the source,and the apparent resistivity tends to the plane wave apparent resistivity. Therefore,in order to use current theory of CSAMT sounding,the receiving distance should be as large as possible. Otherwise,we must use the true controlled source electromagnetic inversion to finish the data analysis with consideration of the source effect.
出处
《地质与勘探》
CAS
CSCD
北大核心
2015年第1期151-156,共6页
Geology and Exploration
基金
国家重大科研仪器专项(NO.2011YQ05006010)资助
关键词
可控源音频大地电磁法
三维
数值模拟
阻抗视电阻率
非平面波效应
controlled source audio magetotelluric(CSAMT),3-D,numerical simulation,impedance apparent resistivity,effect of non-plane wave
