瞬变电磁法同一回线与“8”字形回线一维正反演对比研究

发布时间：2018-07-05 12:35

本文选题：瞬变电磁法同一回线 + “8”字形回线　；参考：《东华理工大学》2015年硕士论文

【摘要】：本文的主要研究内容为同一回线与“8”字形回线一维正反演。首先介绍了瞬变电磁法的国内外的发展以及研究现状,主要包括瞬变电磁法的演变、发展历程、正反演发展概况、瞬变电磁法仪器以及系统的发展现状及趋势。其次,介绍了瞬变电磁法的理论基础及工作原理。然后应用汉克尔变换和G-S变换求解出同一回线装置的一维正演问题,并根据“8”字形回线与同一回线线圈上的几何关系,采用坐标平移法求解出“8”字形回线的一维正演问题,分别作不同地电模型的一维正演曲线图,并对比之。结果表明:同一回线与“8”字形回线正演曲线衰减形态类似,对不同视电阻率的地层都有所反应,不同之处在于“8”字形回线的正演曲线衰减比同一回线快。关于一维反演的研究,首先是视电阻率的定义研究。研究表明:早、晚期的视电阻率只适合极限条件下的视电阻率定义,多数的实际情况并不能满足。只有全区的视电阻率才能满足多数情况下的定义,因此文章在反演时采用全区视电阻率定义。其次对比了平移算法和二分搜索算法对全区视电阻率计算结果,结果表明二分搜索算法在计算晚期视电阻率时更稳定。之后阐述了反演的方法,主要说明了烟圈反演与视电导率反演理论,作者选用了常用的烟圈反演方法进行反演。最后在二分法的基础上,对不同地电模型进行反演成像,绘制出同一回线与“8”字形回线的反演结果曲线对比图,并对比二者的反演效果,结果表明:由于烟圈反演的本身性质决定,这两种装置的反演结果在地层分界面处的视电阻率计算值均会发生畸变;同一回线与“8”字形回线在和模型的拟合程度上都比较理想。不同之处在于“8”字形回线计算出的视电阻率比同一回线略大。为了验证反演结果并研究同一回线与“8”字形回线装置在实际应用上的差异,作者在同一地区进行了这两种装置的实际测量工作,对比二者所得数据的质量以及各自数据解释成果。结果表明:“8”字形回线在抗干扰能力方面优于同一回线,所计算的视电阻率也比同一回线略大,这一点验证了理论上的反演结果。
[Abstract]:The main content of this paper is one-dimensional forward and inverse analysis of the same loop and 8-shaped loop. Firstly, the development and research status of transient electromagnetic method at home and abroad are introduced, including the evolution of transient electromagnetic method, the development course, the general situation of forward and inverse development, the present situation and trend of the instrument and system of transient electromagnetic method. Secondly, the theory and working principle of transient electromagnetic method are introduced. Then using Hankel transform and G-S transform to solve the one-dimensional forward problem of the same loop device, and according to the geometric relation between the "8" shape loop and the same loop coil, The one-dimensional forward modeling problem of "8" zigzag loop is solved by coordinate translation method, and the one-dimensional forward curves of different geoelectric models are made and compared. The results show that the attenuation form of the forward curve of the same loop is similar to that of the "8" curve, and the attenuation of the forward curve of the "8" curve is faster than that of the same loop. The definition of apparent resistivity is the first step in the study of one-dimensional inversion. The results show that the early and late apparent resistivity is only suitable for the definition of apparent resistivity under the limit condition, and most of the actual conditions are not satisfied. Only the apparent resistivity of the whole region can satisfy the definition in most cases, so the definition of apparent resistivity in the whole region is used in inversion. Secondly, the results of translational algorithm and dichotomous search algorithm are compared. The results show that the binary search algorithm is more stable in the calculation of late apparent resistivity. After that, the inversion method is expounded, which mainly explains the theory of smoke ring inversion and apparent conductivity inversion, and the author chooses the commonly used smoke ring inversion method to carry on the inversion. Finally, on the basis of dichotomy, the inversion imaging of different geoelectric models is carried out, and the inversion result curves of the same loop and "8" are drawn, and the inversion results of the two are compared. The results show that the inversion results of these two devices will be distorted at the interface of the formation due to the nature of the smoke ring inversion. Both the same loop and the "8" loop fit well with the model. The difference is that the apparent resistivity calculated by the "8" loop is slightly larger than that of the same loop. In order to verify the inversion result and study the difference between the same loop line and the "8" type loop device in practical application, the author has carried out the actual measurement work of the two devices in the same area. Compare the quality of the two data and the results of their data interpretation. The results show that the anti-jamming ability of "8" loop is better than that of the same loop, and the apparent resistivity calculated is slightly larger than that of the same loop, which verifies the theoretical inversion results.
【学位授予单位】：东华理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P631.325

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