瞬变电磁三分量响应规律研究

发布时间：2019-03-10 20:42

【摘要】：瞬变电磁探测是地球物理探测的主要手段之一，传统的瞬变电磁探测方法仅利用了采集到的垂直分量信息，在复杂地质构造探测中受到了限制，不仅探测精度低，且易产生解释错误。水平分量响应中包含大量的异常体信息，综合分析水平与垂直分量响应可以更准确的对地下异常体进行判定，极大提高了瞬变电磁资料的解释精度。目前，瞬变电磁探测针对于垂直分量已经形成了一套比较完善的测量技术、处理手段和解释方法，而针对水平分量的研究工作却稍显落后。以往对瞬变电磁探测的理论研究、仪器研制和野外实际测量中都只关注于垂直分量的研究，水平分量往往被忽视。水平分量响应幅度小，响应数据复杂，导致了瞬变电磁水平分量的研究利用对瞬变电磁仪器的性能和瞬变电磁响应的解释理论都提出了很高的要求。针对这一问题，本文根据三分量瞬变电磁法的研究和应用现状，简要说明了三分量瞬变电磁探测相比于单一垂直分量瞬变电磁的优越性，建立以导电回线为目标体的瞬变电磁系统响应模型，推导出单一Z分量激发下X、Y、Z三分量响应的表达式，计算并分析了不同条件下三分量响应特征。同时，本文计算分析了大地响应、大地与线圈间非期望互感响应对TEM系统三分量导电回线响应的影响。研究结果表明：X、Y、Z三个分量响应具有各自特征：Z分量与目标体耦合强度大，，响应表现为峰值异常，适用于对目标体的探测与定位；X分量响应为过零点异常，对目标体的边沿、中心等位置以及目标体的倾向反应灵敏；Y分量响应为峰值异常且幅度较小，反映了测线穿过目标体的位置，测线越偏离目标体中心，Y分量响应越强。吊舱高度的改变对响应的幅值影响较大，而对响应曲线形态影响较小。吊舱倾角的改变对响应曲线形态影响较大。发射电流幅值的改变只影响响应幅度，对响应曲线形态无影响。在大地对系统响应的影响中，TER响应衰减速度较快，对TLR响应的影响在早期影响较大，在晚期影响较小。TELR三分量响应与TLER三分量响应相似，都为过零点响应，在响应前期小于零，会减小TLR响应幅度，响应后期大于零，会增加TLR响应幅度。本文的研究成果为瞬变电磁三分量数据的解释应用和瞬变电磁三分量系统标定提供了理论依据。
[Abstract]:Transient electromagnetic detection is one of the main means of geophysical exploration. The traditional transient electromagnetic detection method only utilizes the information of the vertical component collected, which is limited in the exploration of complex geological structure, and the detection accuracy is not only low. And easy to produce interpretation errors. The horizontal component response contains a large amount of abnormal body information. Comprehensive analysis of the horizontal and vertical component response can more accurately determine the underground abnormal body, which greatly improves the interpretation accuracy of the transient electromagnetic data. At present, the transient electromagnetic probe has formed a set of perfect measurement techniques, processing methods and interpretation methods for the vertical component, but the research work on the horizontal component is a little behind. In the past, the theoretical research of transient electromagnetic detection, the development of instruments and the field measurement only focus on the study of vertical component, while the horizontal component is often ignored. The response amplitude of the horizontal component is small and the response data are complex, so the research on the horizontal component of the transient electromagnetic has put forward a high demand for the performance of the transient electromagnetic instrument and the interpretation theory of the transient electromagnetic response. In order to solve this problem, according to the research and application status of three-component transient electromagnetic method, this paper briefly explains the superiority of three-component transient electromagnetic detection compared with single vertical component transient electromagnetic method. The response model of transient electromagnetic system with conductive loop as target body is established. The expression of three-component response of X, Y and Z under single Z-component excitation is derived. The response characteristics of three-component response under different conditions are calculated and analyzed. At the same time, the influence of geodetic response, undesired mutual inductance response between earth and coil on the three-component conductive loop response of TEM system is calculated and analyzed in this paper. The results show that the response of X, Y and Z components has their own characteristics: the coupling intensity between Z component and target body is large, and the response is peak anomaly, which is suitable for detecting and locating the target body; The X-component response is zero-crossing anomaly, and it is sensitive to the edge and center position of the target body and the tendency of the target body. The response of Y component is abnormal and the amplitude is small, which reflects the position of the line passing through the target body. The more the line deviates from the center of the target body, the stronger the response of the Y component is. The change of pod height has great influence on the amplitude of the response, but has little effect on the shape of the response curve. The change of pods inclination has a great influence on the shape of response curve. The change of emission current amplitude only affects the response amplitude, but has no effect on the shape of response curve. Among the effects of the earth on the response of the system, the attenuation of TER response is faster, and the influence on TLR response is greater in the early stage than in the later stage. The TELR three-component response is similar to the TLER three-component response, all of which are zero-crossing response. When the initial response is less than zero, the TLR response amplitude will be reduced, and the later response will be greater than zero, which will increase the TLR response amplitude. The results of this paper provide a theoretical basis for the interpretation and application of the transient electromagnetic three-component data and the calibration of the transient electromagnetic three-component system.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P631.325

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