瞬变电磁法探测断层构造的有效性分析  

Analysis of effectiveness of transient electromagnetic method in detecting fault structures

作　　者：李丹 Li Dan(Xi′an Research Institute Co.,Ltd.,China Coal Technology & Engineering Group Corp.,Xi′an 710077,China)

机构地区：[1]中煤科工集团西安研究院有限公司,陕西西安710077

出　　处：《能源与环保》2022年第3期93-100,共8页CHINA ENERGY AND ENVIRONMENTAL PROTECTION

基　　金：国家重点基础研究发展计划(973计划)资助项目(2017YFC0804105);中国煤炭科工集团有限公司科技创新创业资金专项(2018MS006)。

摘　　要：为了研究瞬变电磁法探测断层构造的有效性,以典型的K型、H型层状模型为基础,建立了不同断距断层构造的理论模型,分析了不同断距条件下瞬变电磁的响应特征。发现当断层构造存在时,瞬变电磁晚期视电阻率断面表现为连续渐变电性变化规律:在上升盘区域,中间层层厚变大,异常幅值增强;在断层带附近,表现为层厚变薄,电阻率异常幅值减弱;在下降盘区域,电阻率异常幅值减弱,层厚变薄,且断距越大,瞬变电磁响应的幅值变化也越大。进一步对8组理论断层构造模型数据和野外实测断层构造数据进行瞬变电磁一维OCCAM反演,发现断层构造在瞬变电磁一维反演电阻率断面也呈现为连续电性变化,表现为中间电性标志层厚度的减小或者增大、幅值的增强或者减弱,与实际断层构造不是对应关系。但是通过综合分析,只要能正确认识断层构造上升盘、断层带和下降盘的电性特征,依然可以定性判断断层构造的位置。In order to study the effectiveness of transient electromagnetic method(TEM)in detecting fault structures,theoretical models of fault structures with different fault distances were established based on typical K-type and H-type layered models,and the transient electromagnetic response characteristics under different fault distances were analyzed.It was found that when the fault structure exists,the apparent resistivity section of the late-time shows a continuous gradual electrical variation law.In the rising disk area,the middle layer thickness becomes larger and the abnormal amplitude increases.In the vicinity of the fault zone,the thickness of the layer becomes thinner and the amplitude of the abnormal resistivity decreases.In the descending panel area,the amplitude of abnormal resistivity decreases,the thickness of the layer becomes thinner,and the larger the fault distance is,the greater the amplitude change of transient electromagnetic response is.Further fault structure of 8 group theory model and field data measured fault structure data for transient electromagnetic one-dimensional OCCAM inversion,found fault structure in transient electromagnetic one dimensional inversion of resistivity section also presents a continuous electrical change,show the intermediate electrical logo layer thickness decrease or increase,the amplitude of the increase or decrease,and the actual fault structure is not a one-to-one relationship.However,through comprehensive analysis,the location of the fault structure can still be determined qualitatively as long as the electrical characteristics of the uplift wall,fault zone and descending wall of the fault structure can be correctly understood.

关 键 词：瞬变电磁法 断层构造 一维反演 OCCAM 理论模型 

分 类 号：P631[天文地球—地质矿产勘探]