基于井中垂直磁场的可控源电磁法深部矿产探测研究  

Deep Mineral Exploration of CSEM Based on Vertical Magnetic Field in Borehole

作　　者：李棂泽 郭长安 郭俊波 王堃鹏 王向鹏 许洋 LI Lingze;GUO Chang’an;GUO Junbo;WANG Kunpeng;WANG Xiangpeng;XU Yang(China Anneng Group Third Engineering Bureau Co.,Ltd.,Chengdu,Sichuan 611130;Geophysical Survey Center of China Geological Survey,Langfang,Hebei 065000;Key Laboratory of Earth Exploration and Information Technology of Ministry of Education(Chengdu University of Technology),Chengdu,Sichuan 610059;Sichuan Metallurgical Geological Survey and Design Group Co.,Ltd.,Chengdu,Sichuan 610021)

机构地区：[1]中国安能集团第三工程局有限公司,四川成都611130 [2]中国地质调查局地球物理调查中心,河北廊坊065000 [3]地球勘探与信息技术教育部重点实验室(成都理工大学),四川成都610059 [4]四川省冶勘设计集团有限公司,四川成都610021

出　　处：《地质与勘探》2023年第6期1293-1303,共11页Geology and Exploration

基　　金：中国地质调查局“北山及邻区区域地球物理调查”项目(编号:DD20230254);国家自然科学基金项目(编号:42004057)联合资助。

摘　　要：我国浅部可用矿产资源量日益枯竭,如何提高深部矿产探测效果是亟待解决的重要问题。然而对于深部资源的探测,受限于地面地球物理勘探技术的探测精度、深度以及抗干扰能力,传统的电磁法难以在地表准确探测到深部隐伏矿的有用信息。为提高可控源电磁法(CSEM)的分辨率,本文利用矿井作为接收电磁总场响应的测点位置,采集井中垂直磁场数据BZ,获取地下电导体三维空间分布信息。采用有限差分法正演研究不同矿井位置对异常体的正演响应,结果表明矿井越靠近地下异常体边界,响应越大。基于有限内存拟牛顿法(LBFGS)所实现的快速三维反演,进一步证实井中磁场数据可以有效提升对深部空间信息的识别。最后,井中磁场数据与地面磁场数据结合起来实施的联合反演,实现了从浅到深的高精度成像,为实际深部矿产勘探提供了理论支撑。The available shallow mineral resources in China are increasingly depleted,and how to improve the effectiveness of deep mineral exploration is an important issue urgently to be solved.However,for the exploration of deep resources,limited by the detection accuracy,depth,and anti-interference ability of surface geophysical exploration technology,traditional electromagnetic methods are difficult to accurately detect useful information of deep hidden mines on the surface.In order to improve the resolution of controllable source electromagnetic method,this work used a borehole as the measuring point location for receiving the total electromagnetic field response,collected vertical magnetic field data BZ in the borehole,and obtained three-dimensional spatial distribution of underground electrical conductors.The finite difference method was used to study the forward response of different borehole locations to abnormal bodies.The results show that the closer the borehole is to the boundary of the underground abnormal body,the greater the response is.The fast 3D inversion based on the limited-memory-Broyden-Fletcher-Goldfarb-Shanno(LBFGS)method further proves that the borehole magnetic field data can effectively improve the recognition of deep spatial information.Finally,the joint inversion of borehole magnetic field data and surface magnetic field data has achieved high-precision imaging from shallow to deep,providing theoretical support for practical deep mineral exploration.

关 键 词：可控源电磁法 深部探矿 井中 垂直磁场 有限内存拟牛顿法 

分 类 号：P631[天文地球—地质矿产勘探]