高频大地电磁在地下水勘查中的应用研究

发布时间：2018-08-30 15:53

【摘要】：大地电磁测深是以吉洪诺夫(A.N.Tikhonov,1950)和卡尼亚(L.Cagnird,1953)所提出的经典理论为基础。大地电磁测深法在勘查隐伏金属矿产、预测地震、研究火山深部构造、研究地壳岩石圈结构、研究隐伏岩溶水结构、调查地热田等方面都发挥着重要作用。大地电磁正演计算是我们了解地下地质体对电磁场响应的重要手段。大地电磁反演是根据已有的大地电磁响应还原大地介质的电性分布。因此,对大地介质进行正反演模拟计算,进一步把握大地介质的大地电磁响应和影响规律。为了更加真实的反映地下不良地质体的分布情况,本文基于正演模拟指导反演解释。论文的主要内容包括以下几方面:1)分析MT正反演的研究现状、概述本文研究的主要内容和结构安排。2)研究MT测深基本原理。从Maxwell方程组出发,推导电磁场波动方程和边界方程。分析均匀半空间和二层介质条件下大地电磁场的表达形式。3)研究MT正演基本原理。着重分析利用有限单元法求解大地电磁正演问题。对一维、二维模型有限元正演的数值模拟、有限单元的剖分、边值问题、变分问题进行详细的推导。4)研究MT反演基本原理。研究基于先验约束条件的正则化反演、最小二乘光滑约束反演,以及几种常用二维反演方法目标函数的构造过程。5)研究EH4电磁测深系统的原理和EH4系统野外工作方法技术,将其应用于宁夏某地区地下水资源勘查项目。在分析区域水文地质条件和地球物理特征的基础上,结合前人的研究成果,对实测资料进行快速松弛二维处理,并进行地质解释,为勘查区域的地下水水质做出评价。6)总结本文主要的研究成果、存在的问题以及进一步的研究方向。
[Abstract]:The magnetotelluric sounding is based on the classical theory put forward by Tikhonov (A.N. Tikhonovi 1950) and Kania (L. Cagnirdl 1953). Magnetotelluric sounding (MT) plays an important role in prospecting hidden metallic minerals, predicting earthquakes, studying deep volcanic structures, studying crustal lithospheric structures, studying concealed karst water structures, and investigating geothermal fields. Magnetotelluric forward modeling is an important means for us to understand the response of underground geological bodies to electromagnetic fields. Magnetotelluric inversion is based on the existing magnetotelluric response to reduce the electrical distribution of magnetotelluric media. Therefore, the magnetotelluric response and the influence law of the earth medium are further grasped by the forward and inverse simulation calculation of the earth medium. In order to reflect the distribution of underground bad geological bodies more realistically, the inversion interpretation is guided by forward modeling. The main contents of this paper are as follows: 1) analyzing the present situation of MT forward and inverse modeling, summarizing the main contents and structure of this paper) studying the basic principle of MT sounding. The electromagnetic wave equation and boundary equation are derived from Maxwell equations. The basic principle of MT forward modeling is studied by analyzing the expression form of magnetotelluric field in homogeneous half-space and two-layer medium. The finite element method is used to solve the forward magnetotelluric problem. The basic principle of MT inversion is studied by deducing the numerical simulation of finite element forward modeling, finite element dissection, boundary value problem and variational problem in detail. The regularization inversion based on a priori constraint condition, the least square smoothing constrained inversion, and the construction process of objective function of several commonly used two-dimensional inversion methods are studied.) the principle of EH4 electromagnetic sounding system and the field work method of EH4 system are studied. It is applied to the exploration project of groundwater resources in a certain area of Ningxia. Based on the analysis of the regional hydrogeological conditions and geophysical characteristics, combined with the previous research results, the measured data were processed rapidly by two dimensional relaxation, and the geological interpretation was carried out. In this paper, the main research results, existing problems and further research directions are summarized.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P631.325;P641.7

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