【作者】 肖晓；

【导师】 汤井田；

【作者基本信息】 中南大学 ， 地球探测与信息技术， 2010， 博士

【摘要】 被动源电磁测深法以其特有的优势,已经越来越多地被应用于实际工作中。然而,其反演解释技术相对落后,限制了其资料解释的水平。本文在国家高技术研究发展计划(863计划)“被动源电磁测深的多尺度自适应双模联合反演研究(2006AA06Z105)”的资助下,进行了基于背景分离的被动源电磁测深双模联合反演研究,具有重要的理论和实际意义。本文基于最小构造的思想,对被动源电磁测深法双模联合快速反演展开研究,重点研究了灵敏度矩阵的快速计算和基于多分辨小波分解理论的背景分离反演方法。论文通过理论分析、数值模拟、模型试验以及实际应用等手段,研究了如何有效地利用被动源电磁测深两种模式的数据联合反演提高反演的精度,同时在加快反演速度方面做了一定的研究工作。首先,论文研究了带模型约束的被动源电磁测深双模联合反演的目标函数,对模型参数和各种数据残差进行不同的权重的单独约束,能有效地利用各种数据相互约束反演获得光滑的地电模型；针对被动源电磁测深反演的实际情况,设计了正演与反演的双重网格方案,在保证正演精度的同时,提高了反演速度,且实际操作简单,管理方便。在此基础上,编程实现了被动源电磁测深TE与TM双模联合最小构造反演,并针对七种典型电磁模型,系统分析了视电阻率与相位差四种观测数据及其联合反演的效果,总结出具有指导意义的规律,并应用于内蒙某矿区的实际数据反演。接着,论文在进行一维大地电磁灵敏度分析的基础上,以高频大地电磁测深法为例,利用数值模拟方法,分析了二维情况下各种观测资料的灵敏度随模型电阻率、频率以及空间坐标的变化和衰减规律,得出了二维灵敏度在趋肤深度一定的情况下随空间坐标迅速衰减的结论；在此基础上,提出了利用趋肤深度限定范围进行快速灵敏度矩阵计算,并应用于被动源电磁测深双模联合反演中,进行了模型试验,结果表明,该方法大大加快了反演的速度。然后,论文利用Mallat小波多分辨分析,分离出被动源电磁测深法地表电磁响应中的背景电磁响应信息和异常电磁响应信息,并进行模型试验验证了方法的应用效果。在此基础上,提出了基于背景分离的二维被动源电磁测深反演方案,对背景电磁响应进行快速反演,并用该反演结果约束异常区域的反演,达到了背景分离反演的目的。模型试验表明,基于背景分离的被动源电磁测深双模联合反演的结果,冗余构造少,反演速度快。最后,总结了全文的主要内容和创新工作,并指出了研究工作的不足之处和今后工作的建议。更多还原

【Abstract】 Passive source electromagnetic sounding method has increasingly been used in practical work for its unique advantages. However, the inversion method is lag behind which restricts the level of data interpretation results. With the support of National High Technology Development "863" Project-"Multi-scale Self-adapting Two-mode Joint Inversion of Passive Source Electromagnetic Sounding", This article researched a two-mode joint inversion method of the passive source electromagnetic sounding data based on background subtraction.This paper studied a rapid two-mode joint inversion of the passive source electromagnetic sounding data based on the idea of minimum structure. The main focus is the fast computing of the sensitivity matrix and the background subtraction inversion method based on the theory of wavelet multi-resolution decomposition. By theoretical analysis, numerical simulation, model test and practical application, the method of improving the inversion accuracy with making effective use of joint two-mode data is researched; meanwhile, speed is also discussed.Firstly, the objective function of the joint inversion of the two-mode passive source sounding with model constraints is built. Model parameters and data residual errors are restricted individually with different weights which can use various kinds of data effectively to get a smoother model. For the practical situation of the passive source sounding, a double grid of forward and inversion is designed which accelerate the inversion speed without loss of forward significance, moreover, it’s easy for operation and management. On this basis, the two-mode joint inversion of passive source electromagnetic sounding data based on minimum structure is implemented by programming. The effects of individual and joint inversion with four kind of sounding data is analysed by inversion test to seven typical geoelectricity model, which lead to some significative conclusions. The inversion method is applied to real data of a mining area in Inner Mongolia in the following part. Secondly, on the basis of the analysis of one-dimensional magnetotelluric sensitivity function, by using numerical simulation method, high-frequency magnetotelluric sounding on two-dimensional model is taken for example to show the relationships between the sensitivity of various observational data and model resistivities, frequency and spatial coordinates, and the conclusion summarized is that the sensitivity will decay fast when spatial coordinates changed in the condition of a constant skin depth. With this conclusion, a method of fast computing the sensitivity matrix by limiting the rang with skin depth is presented and applied to the passive source electromagnetic sounding two-mode joint inversion and proved by model test that it can greatly accelerated the inversion speed.Thirdly, based on the theory of Mallat wavelet multi-resolution decomposition, a discussion and computing formula of obtaining background information from the surface electromagnetic response of the passive source electromagnetic sounding method is provided and verified by test. On this Basis a two-mode joint inversion method of passive source sounding based on the background subtraction is presented. The inversion of the background electromagnetic response is done individually while the result resistivity is imposed on the background outside the abnormal regions of the model for restricting the inversion, only the abnormal regions changes will be calculated. Model tests show that this method can effectively reduce the redundant structure and the elapsed time.Finally, the main work and innovations involved and some limitations in current research are pointed out and recommendations for future research are given in the conclusion part.更多还原