3-D terrain effect and numerical modeling on TEM

摘要

The Transient Electromagnetic (TEM) nowadays is the situation of the lower level of the 1 dimension(l-D) interpretation in field work. When TEM is applied widely in Geo-exploration, topography problems become very important in room interpretation today. Through studies, We found that complex terrain causes artifactitious electromagnetic (EM) field great effects and noises,it also will give us some indeterminate results in interpretation work. Basing on studies of some scholars,this paper has deduced the total field formulas of the 3 dimension(3-D) boundary element method (BEM) from the EM equations, transformed EM fields from frequency domain to time domain using Guptasarma algorithm, modeled EM field of 3D TEM under the condition of complex terrain for the central/outside loop array,. The technique has high computed speed using 'pieces sources method'and equivalent method.The paper contrasted also among field components and seeked to find the change law about total abnormal field value about uneven terrains. Lastly, this paper put forward some valuable conclusions and advices for TEM practice work.