【作者】 席振铢；

【导师】 汤井田；

【作者基本信息】 中南大学 ， 地质资源与地质工程， 2013， 博士

【摘要】 针对目前天然场源倾子张量测量信噪比低,数据不可靠以及只能发现横向不均匀地质体,不便纵向电性测深的缺点,本文在“十一五”国家科技支撑计划项目(2007CB8416608)的支持下开展了人工源频率倾子测深法(Artificial Source Frequency Tipper Sounding Method,简称,ASFTSM)的研究,试图解决高精度倾子张量测深的科学问题,为精确地球物理探测提供一种途径。本文从人工源的电磁测深理论出发,推导了人工源均匀半空间倾子张量的表达式,构建了频率倾子参数与大地介质电性参数的函数,从理论上论证了人工源倾子张量测深的可行性,并且采用正交复合源和频率倾子转化视电阻率的技术,有效解决场源扇区对测点布置的限制和测量结果的影响,拓宽了单个源的工作区域,实现频率倾子远区全方位测量。为了论证频率倾子测深的可行性,论文推导单源和正交复合人工源均匀水平层状介质的倾子张量递推公式,采用自适应数值滤波技术计算了单个电偶源、单个水平磁偶源、正交电偶源、正交水平磁偶源的典型层状模型的频率倾子响应,结果表明频率倾子能够有效反映并区分层状介质的电性特征,从而论证了人工源频率倾子张量的可行性,通过比对单源和正交复合源测深曲线,证明多源极化能够有效解决场源对测量结果的影响。为了研究人工源倾子张量对复杂地质体的响应规律,论文采用ASFTSM2.5维有限单元法数值计算方法,模拟计算了ASFTSM典型二维地质倾子张量各参数响应规律,研究结果表明频率倾子可以有效反映地下复杂地质体的电阻率电性纵横向变化；同时,倾子振幅、倾子椭圆率以及实感应矢量等倾子张量辅助参数,能够提取异常体的维数、边界、倾向、空间位置等地质体几何信息,为精确定位地质体提供一种途径；论文通过数值计算比对了人工源频率倾子与天然场卡尼亚电阻率对近地表二维低阻体的响应,结果表明人工源频率倾子测深法基本消除了基于卡尼亚电阻率测深的近地表的局部不均匀地质体引起的静态效应。论文通过理论和数值计算研究ASFTSM的纵横向探测能力,结果表明ASFTSM不仅具有探测横向不均匀地质体的能力而且也具有纵向电性分辨力,特别是对低阻异常灵敏度高；并且,从场源、测量方式、测区范围、观测方案、分辨率问题、地形影响、适用条件等方面,研究总结了ASFTSM的工作方法技术,提出了补强天然场人工源方案、倾子张量测量、远区全方位观测等技术方案。通过组装的ASFTSM发射和接收系统,在长沙月亮岛和山东招远金属找矿野外试验,论证ASFTSM在金属矿的勘探的有效性和应用前景。通过本文的研究,奠定了ASFTSM法的理论基础、工作方法技术和数据处理解释的原则,提供了一种地球物理勘探新方法,为地球物理精确勘探提供了一种途径。更多还原

【Abstract】 The natural source tipper tensor survey exists disadvantages, on one hand, the limited signal-to-noise ratio makes the field data unreliable; on the other hand, the vertical electrical sounding is more difficult than the lateral prospecting.Therefore, this paper presents the Artificial Source Frequency Tipper Sounding Method (ASFTSM), with the support of11th Five-Year project (2007CB8416608) from Department of Science and Technology, to solve the problem of high-precision tipper tensor sounding and to provide a way for precise geophysical exploration.Based on the sounding theory of artificial source, the expressions of tipper tensor of artificial source in homogeneous half space is deduced, the function of frequency tipper parameter and electrical parameter of the earth is built, the feasibility of artificial source tipper tensor sounding is theoretically proved, the restriction of arrangement of measuring points and the affect of measurement result which caused by field source sector is solved, the work area of single source is broadened, full measurement of frequency tipper in the far zone is achieved.In order to demonstrate the feasibility of frequency tipper sounding, and to derive the recurrence formula of tipper tensor of the single source and compound orthogonal artificial source in homogeneous layered media, adaptive numerical filtering technique is applied to calculate the frequency tipper response of single electric dipole source, single horizontal magnetic dipole source, orthogonal electric dipole source and horizontal orthogonal source in typical layered models, the results show that frequency tipper can effectively reflect and distinguish the electrical characteristics of layered media. The feasibility of frequency tipper tensor of artificial source is demonstrated. By comparing the sounding curves of single source and orthogonal source, the affect of field source to measurement results can be solved by multi-source polarization is proved.In order to study the response of artificial source tipper tensor to complex geological target, the ASFTSM2.5-dimensional finite element numerical method is used to simulate the response pattern of tipper tensor parameters to ASFTSM typical two-dimensional geological models. The study shows that frequency tipper can effectively reflect the vertical and horizontal change of electrical properties of complex geological body. Meanwhile, with the aid of tipper amplitude, tipper elasticity and the real induction vector and tensor tipper, geometric information such as dimension, border, tendency and spatial location of the target can be extracted to precisely position the geological body. Through numerical calculation, the responses of artificial frequency tipper and natural field Cagniard resistivity to near-surface2-dimensional low resistivity body are compared; the result shows that the static shift caused by near-surface uneven geological body based on Cagniard resistivity sounding is basically eliminated by artificial source frequency tipper sounding method.The vertical and horizontal detective ability of ASFTSM is studied through theoretical and numerical calculation, the result shows that ASFTSM not only has the ability of detecting lateral heterogeneous geological body but also has longitudinal electrical resolution, it is especially sensitive to low resistivity geological body. Also, the field source, measurement, survey scope, observing program, resolution, topographic effect and applicable condition of ASFTSM are studied and summarized, technical programs such as reinforcing the natural field through adding artificial source, tipper tensor measurement, full observation in the far zone are proposed. Field tests using the assembled ASFTSM transmit and receive system at Moon Island of Changsha and Zhaoyuan Shandong show the validity and prospects of ASFTSM in metal ore exploration.Through a series of research in the paper, the theoretical foundation, techniques, data processing and interpretation of ASFTSM are established. ASFTSM is a new method of geophysical exploration, providing a way for accurate geophysical prospecting.更多还原