地球物理学进展 ›› 2018, Vol. 33 ›› Issue (4): 1461-1468.doi: 10.6038/pg2018BB0518

• 应用地球物理学Ⅰ(油气及金属矿产地球物理勘探) • 上一篇    下一篇

基于MATLAB语言的二维大地电磁OCCAM快速反演

陈润滋1,2,3,安志国1,2,3,*(),杨良勇1,2,3   

  1. 1. 中国科学院地质与地球物理研究所,页岩气与地质工程重点实验室,北京 100029
    2. 中国科学院地球科学研究院,北京 100029
    3. 中国科学院大学,北京 100049;
  • 收稿日期:2017-11-07 修回日期:2018-05-19 出版日期:2018-08-20 发布日期:2018-09-13
  • 通讯作者: 安志国 E-mail:zgancas@mail.iggcas.ac.cn
  • 作者简介:陈润滋,男,硕士研究生,主要从事地球电磁正反演研究.(E-mail: chenrunzi15@mails.ucas.edu.cn)
  • 基金资助:
    中国科学院A类战略性先导科技专项《智能导钻技术装备体系与相关理论研究》项目五“智能导钻系统集成与试验”(XDA1405)

Fast OCCAM inversion for two-dimensional magnetotelluric based on MATLAB language

CHEN Run-zi1,2,3,AN Zhi-guo1,2,3,*(),YANG Liang-yong1,2,3   

  1. 1. Key Laboratory of Shale Gas and Geoengineering, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
    2. Institutions of Earth Science, Chinese Academy of Sciences, Beijing 100029, China
    3. University of Chinese Academy of Sciences, Beijing 100049, China;
  • Received:2017-11-07 Revised:2018-05-19 Online:2018-08-20 Published:2018-09-13
  • Contact: Zhi-guo AN E-mail:zgancas@mail.iggcas.ac.cn

摘要:

以TM模式为例,基于MATLAB语言对二维大地电磁快速正反演算法进行了研究.针对有限元正演计算中多次矩阵赋值和多频率计算的特点,引入了矢量化编程和并行计算两种策略,编制了实现快速正演的MATLAB程序.以此为基础,开展了基于OCCAM理论的反演算法研究.首先,使用拟正演手段对偏导数矩阵进行快速求取.其次,为平衡模型参数与拟合误差的关系,采用了固定步长减小的拉格朗日乘子,简化了拉格朗日乘子的求解过程,提高了反演计算的效率.最后,对模型数据进行反演,结果显示反演算法收敛快速、稳定性好.

关键词: 大地电磁, TM模式, 有限元正演, OCCAM反演

Abstract:

Based on MATLAB language with the example of TM polarization mode,the fast modeling and inversion algorithm of two-dimensional magnetotelluric was studied. During the forward modeling,vectorization programming and parallel computing were introduced to improve the speed of matrix assignment and multifrequency calculation. Then,the OCCAM inversion algorithm was described. Firstly,quasi forward method was carried out to calculate the partial derivative matrix rapidly. Secondly,as for Lagrange multiplier, a reducing fixed step size was adopted to balance the difference between model parameters and fitting errors, which could simplify the solving process of the Lagrange multiplier, and improve the calculation efficiency. Therefore, the inversion algorithm could converge fast, and the result is stable.

Key words: magnetotelluric, TM mode, finite element method modeling, OCCAM inversion

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