磁源瞬变电磁拟大地电磁二维反演方法技术研究

发布时间：2018-03-12 09:25

本文选题：磁源瞬变电磁　切入点：拟大地电磁二维反演　出处：《长安大学》2015年硕士论文　论文类型：学位论文

【摘要】：磁源瞬变电磁方法以其独特的优点广泛的应用于矿产资源勘查和环境工程勘查等领域,进入新世纪以来,深部探矿和工程勘查都要求高精度、定量的解决地质问题。到目前为止,尚无成熟的瞬变电磁二、三维反演技术,在一定程度上制约了该方法的应用。本文旨在研究磁源瞬变电磁二维反演理论,考虑到直接利用瞬变电磁二、三维正演作最优化反演的困难,探索了另外一条实现瞬变电磁二维反演的途径,实现了其二维反演解释,本文将重点围绕磁源瞬变电磁一维正演理论、磁源瞬变电磁全区视电阻率计算、磁源瞬变电磁数据和大地电磁数据的时频转换关系以及磁源瞬变电磁数据拟大地电磁二维反演等问题进行分析和研究。基于磁源瞬变电磁一维正演理论和垂直磁感应强度分量定义的全区视电阻率,从理论上研究了瞬变电磁全区视电阻率和大地电磁卡尼亚视电阻率的相似性,选取最佳时频转换系数进行瞬变电磁全区视电阻率和卡尼亚视电阻率的时频转换。对于一维和三维理论模型,进行拟大地电磁一维和二维反演。一维层状反演结果表明:反演电阻率与实际模型电阻率相对误差均小于5.5%;反演深度与实际模型深度相对误差均小于6.7%,因此可利用该方法进行磁源瞬变电磁一维反演。三维模型回线源瞬变电磁响应拟大地电磁二维反演结果表明:主剖面和旁测线TE和TM联合反演结果与实际低阻体在纵、横向上均吻合较好,且不会带来假异常,优于TE模式反演和TM模式反演结果及异常体外测线反演结果;因此三维异常体上方测线选取拟大地电磁二维TE和TM联合反演方式,可较准确的实现瞬变电磁三维响应的二维反演。对陕西某矿区磁源瞬变电磁实测资料利用拟大地电磁反演方法进行二维反演,处理结果表明:联合反演的结果优于TE模式反演结果和TM模式反演结果;根据15、17和19线联合反演结果,并结合矿区岩(矿)石电性特征、成矿构造特征和化探异常范围,推断了反演结果中的低阻异常可能与成矿相关,取得了较好的地质效果。最后总结得出一套基于拟大地电磁二维反演方法技术的磁源瞬变电磁实测资料处理流程,使得磁源瞬变电磁数据利用拟大地电磁反演方法实现了其二维反演解释。
[Abstract]:Magnetic source transient electromagnetic method is widely used in mineral resources exploration and environmental engineering exploration with its unique advantages. Since the beginning of the new century, the deep prospecting and engineering exploration require high accuracy. Up to now, there is no mature transient electromagnetic two and three dimensional inversion technology, which restricts the application of this method to some extent. Considering the difficulty of direct use of transient electromagnetic two and three dimensional forward inversion, another way of realizing transient electromagnetic 2-D inversion is explored and its two-dimensional inversion interpretation is realized. This paper focuses on the theory of one-dimensional forward modeling of transient electromagnetic field of magnetic source and the calculation of apparent resistivity in the whole region of transient electromagnetic field of magnetic source. The time-frequency conversion relationship between magnetic source transient electromagnetic data and magnetotelluric data and the quasi-magnetotelluric inversion of magnetic source transient electromagnetic data are analyzed and studied. Based on the one-dimensional forward theory of magnetic source transient electromagnetic and vertical magnetic field. The whole area apparent resistivity defined by the induction intensity component, The similarity between the apparent resistivity of the whole transient electromagnetic region and the apparent resistivity of magnetotelluric Kania is studied theoretically. The optimum time-frequency conversion coefficient is selected for the time-frequency conversion of apparent resistivity and Kania apparent resistivity in the whole transient electromagnetic region. The inversion results show that the relative error between the inversion resistivity and the actual model resistivity is less than 5.5, and the relative error between the inversion depth and the actual model depth is less than 6.7. Using this method, the transient electromagnetic inversion of magnetic source is carried out. The results show that the inversion result of te and TM of main profile and side line is longitudinal with the actual low resistivity body, and the result of pseudomagnetotelluric inversion of transient electromagnetic response of three-dimension model loop source is longitudinal. It is superior to te model inversion, TM model inversion result and anomalous external line inversion result, so the pseudomagnetotelluric 2D te and TM joint inversion method is chosen over the 3D anomaly body. 2D inversion of 3D transient electromagnetic response can be realized more accurately. The pseudomagnetotelluric inversion method is used to invert the transient electromagnetic data from a mining area in Shaanxi province. The results show that the results of joint inversion are superior to those of te model and TM model, and according to the joint inversion results of line 1517 and 19, combined with the electrical characteristics of rock (ore) in the ore area, the metallogenic structure characteristics and geochemical anomaly range. It is inferred that the low resistivity anomaly in inversion results may be related to mineralization, and good geological effect has been obtained. Finally, a set of processing flow of magnetic source transient electromagnetic measured data based on pseudomagnetotelluric inversion technique is concluded. The magnetic source transient electromagnetic data are interpreted by pseudomagnetotelluric inversion method.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P631.325

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