回线源瞬变电磁法的一维Occam反演

One-dimensional Occam’s inversion for transient electromagnetic data excited by a loop source

基于Dipole 1D一维正演程序和Occam算法开发了回线源瞬变电磁法一维反演程序,并以四层介质模型验证了其正确性。对于倾斜界面模型,待反演数据由时域矢量有限单元法三维正演计算,通过对比实际模型和等效模型的反演结果,说明了一维反演可直接应用于此类情形。最后,开展了那仁宝力格煤田玄武岩深部探测案例研究。在反演电阻率断面图中,玄武岩整体形态呈"锅底状",与多个钻孔资料吻合良好,进一步验证了该反演程序的正确性。

A 1 D inversion code is developed for the loop-source transient electromagnetic method(TEM)based on the open-source code Dipole1 D and Occam’s algorithm.This code is tested by a four-layer stratified model.Then,the model with a tilted earth-air interface is considered,for which the synthetic data are calculated by 3 D finite-element method.The inversion results show that 1 D inversion can be directly used for the scenario with tilted interface.Finally,this 1 D inversion code is used for a field case,in which TEM is employed to delineate the 3 D distributed domains of a basalt which intruded into shale and sandstone.The inversion result shows that the thickness of the basalt coincides with the drilling data,and the shape of the basalt like a pot bottom.