层状全空间瞬变电磁响应理论研究  

Research on layered whole-space response of underground transient electromagnetic method

作　　者：刘建鹏 杨海燕[2] 焦俊俊[3] 陈静 黄刚 彭峰 LIU JianPeng;YANG HaiYan;JIAO JunJun;CHEN Jing;HUANG Gang;PENG Feng(Institute 290 of Nuclear Industry,Shaoguan 512029,China;School of Resources and Geosciences,China University of Mining and Technology,Xuzhou 221116,China;State Key Laboratory Breeding Base of Nuclear Resources and Environment,East China University of Technology,Nanchang 330013,China)

机构地区：[1]核工业二九〇研究所,韶关512029 [2]中国矿业大学资源与地球科学学院,徐州221116 [3]东华理工大学省部共建核资源与环境国家重点实验室培育基地,南昌330013

出　　处：《地球物理学进展》2021年第1期202-210,共9页Progress in Geophysics

基　　金：国家自然科学基金资助项目(41974086);国家自然科学基金资助项目(41564001)联合资助。

摘　　要：研究全空间效应的影响因素及变化规律,可以有效地丰富地下瞬变电磁法的正、反演理论体系.为此,首先建立层状全空间模型,推导了全空间的瞬变电磁响应公式,采用快速汉克尔变换和余弦变换求出了回线中心处的感应电动势,对比分析了叠加方法得到的全空间响应,并引入全区视电阻率来分析瞬变电磁场扩散规律和全空间效应影响因素,最后通过实测模型来验证模型的计算效果.结果表明,层状全空间模型计算出的响应值相对误差低于3%,精度较高;叠加方法计算的瞬变电磁响应不是真正的全空间,且全空间响应均大于半空间响应的值;在低阻层存在时,全空间响应早期受电阻率和厚度的影响较强烈,由此发现在全空间条件下减少巷道内低电阻率干扰体是减小盲区的重要手段;在超高阻层存在时,半空间响应仅仅是全空间条件下观测点以上的地层电阻率为无穷大的特殊情况;低阻目标层的视电阻率受目标层埋深与层厚差异的影响,若埋深与厚度相差小则分层效果越好;实测数据的建模结果显示计算方法有一定的正确性.本研究填补了矿井瞬变电磁一维全空间响应研究内容,为实际应用提供了验算基础.Studying the influencing factors and changing laws of the whole-space effect can effectively enrich the forward and inverse theoretical system of the underground Transient Electromagnetic Method(TEM). In this paper, the layered whole-space model is established firstly, and the transient electromagnetic response formula in the whole-space is derived. The induced electromotive force at the center of the loop is calculated by using the Fast Hankel transform and cosine transform. The whole-space response obtained by the superposition method is compared and analyzed, and uses all-time apparent resistivity to analyze the diffusion rule of the transient electromagnetic field and the influence factors of the whole-space effect. Finally, the calculation effect of the model is verified by measuring the model. The results show that the relative error of the response value calculated by the layered whole-space model is less than 3%, and the accuracy is high;the transient electromagnetic response calculated by the superposition method is not the real whole-space, and the whole-space response is greater than the value of the half space response;When the low-resistivity layer exists, the effect of resistivity and thickness on the whole-space response is strong at the early stage. It is found that reducing the low-resistivity interference body in the roadway under the whole-space condition is an important means to reduce the blind area;when the ultra-high resistivity layer exists, the half space response is only the special case that the formation resistivity above the observation point is infinite under the whole-space condition;the apparent resistivity of the low resistivity target layer is affected by the difference between the buried depth and the thickness of the target layer, if the difference between the buried depth and the thickness is small, the stratification effect is better;the modeling results of the measured data show that The calculation method is correct. This study fills in the research content of one-dimension

关 键 词：矿井瞬变电磁法 层状介质 全空间效应 全区视电阻率 

分 类 号：P631[天文地球—地质矿产勘探]