基于灵敏度加权的带地形直流电阻率布极方式及2.5D反演研究

Research on the distribution method of DC resistivity with terrain based on sensitivity weighting and 2.5D inversion

直流电阻率法是一种较常用的地球物理勘探方法,常用于浅层勘探,因此受地形影响较大。其具有较高的勘探分辨率,但不同的布极方式会对灵敏度产生不同的影响。因此,研究不同布极方式下的带地形直流电阻率法反演规律和特点具有一定的意义。这里对带地形的点源直流电阻率法采用有限体积法进行二维正演模拟,然后将该模拟结果引入正则化Tikhonov方法,对直流电阻率不同的布极方式进行反演研究。实现了灵敏度加权的2.5D反演方法,研究了偶极-偶极(dipole-dipole)、单极-偶极(pole-dipole)、偶极-单极(dipole-pole)三种不同布极方式反演效果进行了对比分析。结果表明,dipole-dipole布极方式更为有效地反映出地下异常体的形态。

The direct current(DC)resistivity method,a more commonly geophysical exploration method,is often used in shallow exploration,so it is greatly affected by topography.This method has high exploration resolution,but different layout methods will have different effects on sensitivity.Therefore,it is of certain significance to study the inversion laws and characteristics of the DC resistivity method considering the effect of topography in different layout modes.In this paper,the finite volume method is used for the two-dimensional forward simulation of the point source DC resistivity method including terrain,and then the simulation results are introduced into the regularized Tikhonov method to carry out inversion research on the arrangement of different DC resistivities.The sensitivity-weighted 2.5D inversion method has been realized,and three different pole arrangements of dipole-dipole,pole-dipole and dipole-pole have been tested and analyzed.The results show that the dipole-dipole arrangement method more effectively reflects the shape of the underground anomaly.