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| 直升机航空瞬变电磁正反演方法研究 | |
| 其他题名 | Forward Modeling and Inversion Method for Helicopter Transient Electromagnetic Data |
| 郭睿 | |
| 出版年 | 2017 |
| 学位类型 | 硕士 |
| 导师 | 张立新 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 直升机航空瞬变电磁法(Helicopter Transient Electromagnetic Method, HTEM)是利用直升机作为飞行平台，搭载瞬变电磁(Transient Electromagnetic, TEM) 系统进行探测的地球物理勘查技术。它具有成本低、速度快、通用性好的特点，对于地表植被、沙漠等覆盖区的靶区圈定与快速评价，以及大面积的国土资源普查具有重要的意义。在国家重大科研装备研制项目“深部资源探测核心装备研发”子项目“航空瞬变电磁勘探仪”的支持下，本文开展了航空瞬变电磁的正反演方法研究工作，实现了一维正演及其数值计算方法，推导了正演函数对电阻率偏导数矩阵的解析解，实现了一维Marquardt和拟二维Marquardt反演。围绕Marquardt反演对地层先验信息依赖程度高这一问题，开展了正则化反演方法，实现了Occam反演方法，提出了适用于低阻薄层的反演方法，反映地层锐边界的反演方法及考虑横向连续性的拟二维正则化反演方法，并开发瞬变电磁反演软件。本文所做工作以提高反演分辨力为主要目的，兼顾地电特征的多样性和反演算法的适用性，主要工作和创新点如下：（1）层状大地一维模型正演。推导任意类型场源瞬变电磁响应的通解，并以垂直磁偶极子发射源和圆形回线发射源为例给出正演公式，计算并讨论了不同发射波形对瞬变电磁场的影响，系统地完成了航空瞬变电磁的正演工作。（2）实现了同时反演电阻率和厚度的Marquardt反演。通过选取不同初始模型的算例分析了Marquardt反演的迭代稳定性，针对单测点反演无法保证横向连续的局限性，本文介绍并实现了拟二维Marquardt反演。（3）实现了多种正则化反演方法。首先论述了正则化反演的稳定性，阐述了正则化反演与Marquardt反演相比的优势。此外，实践了经典算法Occam反演，提出了适用于低阻薄层反演的平滑加权一维Occam反演、适用于刻画成层性大地电性界面的锐边界反演以及适用于航空瞬变电磁法的拟二维正则化反演。（4）自主开发的瞬变电磁数据反演软件（Occam反演）。 |
| 英文摘要 | Helicopter Transient Electromagnetic Method (HTEM) is a kind of geophysical exploration and prospecting method which uses helicopters as the platforms to carry Transient Electromagnetic (TEM) systems. This method possesses the advantage of low cost, high efficiency and strong generality. It can be applied not only for quick determination and evaluation of mineral bodies located under the forests and desserts, but also for large area resource survey.Supported by R&D of Key Instruments and Technologies for Deep Resources Prospecting (the National R&D Projects for Key Scientific Instruments), this dissertation focuses on the HTEM forward modeling and inversion method. In this work, the 1D forward modeling and numerical calculation is accomplished, and the partial derivative of the forward modeling function is derived.1D and quasi-2D Marquardt inversion is achieved. To solve Marquardt inversion’s reliance of a prior information about layer interfaces, regularized inversion method including Occam inversion is developed. In addition, this work proposes Smoothness new inversion method suitable for thin layer low resistivity inversion, Sharp Boundary inversion suitable for reflecting geo-electrical interface, quasi-2D regularized inversion suitable for HTEM data inversion, and developed HTEM inversion software.This paper’s research is based on the practical engineering, aiming at improving inversion’s resolution and keeping the algorithm’s generality while taking different geo-electrical characteristics into consideration. The main work and contributions of this dissertation can be summarized as follows:1) 1D layered earth forward modeling. The general solution of arbitrary types of transmitting sources is given. The forward modeling formulas of vertical magnetic dipole and circular loop as transmitting sources are presented as examples. In addition, this paper calculates and discusses the influence of different transmitting current waves to the secondary magnetic responses.2) the Marquardt inversion scheme, which invert resistivity and thickness at the same time, is introduced. By the compassion of the results using different starting models, Marquardt inversion’s stability is analyzed. At last, the quasi-2D Marquardt inversion is presented to overcome the shortage of discontinuity.3) The regularized inversion method is introduced and the stability of regularized inversion is discussed, compared with Marquardt inversion. This work completes the classical Occam inversion, and proposes Smoothness Weighted Occam inversion suitable for thin layer low resistivity inversion, Sharp Boundary inversion suitable for reflecting geo-electrical interface, quasi-2D regularized inversion suitable for HTEM data inversion.4) The software for TEM data Occam inversion is developed. |
| 中文关键词 | 直升机航空瞬变电磁 ; 正演 ; 反演 ; 拟二维 ; 横向连续 |
| 英文关键词 | Helicopter airborne transient electromagnetic method forward modeling inversion quasi-2D laterally continuous |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 电磁场与微波技术 |
| 来源机构 | 中国科学院电子学研究所 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/287879 |
| 推荐引用方式 GB/T 7714 | 郭睿. 直升机航空瞬变电磁正反演方法研究[D]. 中国科学院大学,2017. |
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