三维跨孔电阻率CT观测电极序列优化及必然伪影分布规律总结  

Optimization of the observation electrode array and summary of the distribution law of inevitable artifacts for 3D cross-hole resistivity CT

作　　者：付强 李士强[2,3,4] 闫孝姮 张文伟[2] 李艳红 FU Qiang;LI ShiQiang;YAN XiaoHeng;ZHANG WenWei;LI YanHong(Faculty of Electrical and Control Engineering,Liaoning Technology University,Huludao 125000,China;Institute of Electrical Engineering Chinese Academy of Sciences,Beijing 100190,China;University of the Chinese Academy of Sciences,Beijing 100049,China;Institute of Electrical Engineering and Advanced Electromagnetic Drive Technology,Qilu Zhongke,Jinan 250000,China)

机构地区：[1]辽宁工程技术大学电气与控制工程学院,葫芦岛125000 [2]中国科学院电工研究所,北京100190 [3]中国科学院大学,北京100049 [4]齐鲁中科电工先进电磁驱动技术研究院,济南250000

出　　处：《地球物理学进展》2023年第5期2263-2275,共13页Progress in Geophysics

基　　金：国家自然科学基金项目(52077210);中国科学院科研仪器设备研制项目(YJKYYQ20190005)联合资助。

摘　　要：目前,跨孔电阻率层析成像(Cross-hole Electrical Resistivity Tomography,CHERT)最为常用的观测阵列为三种四电极阵列:AB-MN,AM-BN和AMN-B(A,B为激励电极,M,N为检测电极).三种阵列的探测效果在二维CHERT中已被详细讨论,但缺乏三种阵列在三维CHERT中探测效果的比较分析.本文首先使用Bellmunt提出的跑极方式生成了三种四极观测阵列的电极序列,分析和比较了反应三种序列探测能力的两个参数:灵敏度和模型分辨率分布,从灵敏度分布图中发现了AMN-B序列存在对探测区域底部分辨力不佳的缺陷,结合其灵敏度分布特点提出了一种消除该缺陷的优化AMN-B跑极方式,并由此生成了优化AMN-B序列.然后构建了异常体分布于探测区域8个有代表性位置的三维地电模型,通过数值模拟,对比了AB-MN,AM-BN和优化AMN-B序列对各模型的探测效果,在反演耗时和反演效果两个方面,优化AMN-B序列均具有最优越的性能.同时,定性地分析并总结了各模型反演图像中必然伪影的存在和分布规律,为三维CHERT探测的解释提供了指导.Currently,the most common detection configurations in Cross-Hole Electrical Resistivity Tomography(CHERT)are three four-electrode configurations:AB-MN,AM-BN,and AMN-B(where A and B are exciting electrodes,and C and D are detection electrodes).The comparison of the detection effects of the three configurations has been discussed in detail in two-dimensional(2D)CHERT,but a comparative analysis of the detection effects of the three arrays in three-dimensional(3D)CHERT has not been adequately studied.In this study,first,the electrode arrays of three four-electrode configurations were generated using the method of electrodes moving proposed by Bellmunt.Then,two parameters,sensitivity distribution and model resolution distribution,which reflect the detection ability of the three arrays,are analyzed and compared.The defect of the poor resolution of AMN-B at the bottom of the detection area was found from the sensitivity distribution diagram.Based on its sensitivity distribution characteristics,we propose an optimized way of electrodes moving of AMN-B that can eliminate the defect,and the optimized AMN-B array is generated from this.Next,eight 3D geoelectric models,in which anomalies were distributed in eight representative locations in the detection area,were constructed.The detection effects of AB-MN,AM-BN and the proposed optimized AMN-B arrays on each model are compared through numerical simulations.In terms of both the calculation time and image quality of inversion,the optimized AMN-B array exhibited the best performance.Finally,the laws of existence and distribution of inevitable artifacts in the inversion images of all models were qualitatively analyzed and summarized,which will provide guidance for the interpretation of 3D CHERT.

关 键 词：三维CHERT 跑极方式 四电极序列 灵敏度 探测效果 必然伪影 

分 类 号：P631[天文地球—地质矿产勘探]