大回线源瞬变电磁响应理论研究回顾及展望  

Review and perspective of theoretical study on Large-loop TEM response

作　　者：闫述[1] 薛国强[2] 陈明生[3] 

机构地区：[1]江苏大学计算机科学与通信工程学院,镇江212013 [2]中国科学院地质与地球物理研究所,北京100029 [3]煤炭科学研究总院西安研究院,西安710054

出　　处：《地球物理学进展》2011年第3期941-947,共7页Progress in Geophysics

基　　金：国家自然科学基金项目(40674060)资助

摘　　要：解析公式的求解是电磁探测方法基础理论研究的重要内容.以往用于大回线瞬变电磁法的理论公式,有圆形重叠回线表达式、中心回线表达式.为了更接近勘探工程中使用的矩形回线源,和为提高效率在回线中心1/3区域观测的实际情况,采用了大定源回线的解析公式.由此定义的视电阻率,克服了偏离中心点观测引起的边缘效应,提高了解释精度,也将大定源回线和大回线装置的理论公式统一了起来.基于偶极子微元的大定源回线解析解在瞬变电磁法理论研究中起到了重要作用,但还不能很好地反映近、中区场的响应特征.可以将静电场点电荷直接比拟到时域场中,在回线上对时变点电荷微元进行积分,以获得适合全场区、全期的更精确的理论公式.Solution of analytic expression is important for basic theoretical investigation in the electromagnetic method. The theoretical equations applied in the large-loop transient electromagnetic method used to be expressions of circle coincide-loop and central-loop. In order to fit the rectangular loop used in practical explorations, and consideiing that measurements could be carried out in midis 1/3 area of the loop for higher efficiency, the expression of large rectangular-loop source is adopted. The edged effect could be eliminated by the defined resistivty thereof that the interpretation accuracy, which integrates the rectangular-loop formula with the large-loop formula. Though this analytic solution based on dipole infinitesimal takes an important part in theoretical study on transient electromagnetic method, the response characteristics of the field measured in near or middle-zone could not be expressed sufficiently. The point charge of the electrostatic field could be directly analogized into time-domain field, and the integration would be carried out with the respect of this time variant point charge infinitesimal so as to obtain more exact theoretic formula proper for the whole zone and whole time.

关 键 词：大回线源瞬变电磁法 重叠回线 中心回线 大定源回线 偶极微元 点电荷微元 

分 类 号：P631[天文地球—地质矿产勘探]