基于二次场方法的并行三维大地电磁正反演研究  

Parallel three-dimensional forward modeling and inversion of magnetotelluric based on a secondary field approach

作　　者：秦策[1] 王绪本[1] 赵宁[2] 

机构地区：[1]成都理工大学地球物理学院,成都610059 [2]河南理工大学物理与电子信息学院,河南焦作454000

出　　处：《地球物理学报》2017年第6期2456-2468,共13页Chinese Journal of Geophysics

基　　金：国家自然科学基金项目(41674078);国家自然科学基金青年基金(41204112)联合赞助

摘　　要：快速且高精度的三维大地电磁法正反演是目前研究的热点.由于大地电磁法场源的平面波特性,以往的正演方法大多采用直接求解总场的方法,在边界强加二维边界条件.本文提出了一种基于二次场方法的三维大地电磁法正演算法,将平面波在层状背景模型中的响应作为场源项,得到二次场满足的偏微分方程,并利用交错网格有限差分法求取二次场.与其他学者的基于总场方法的结果的对比证明了本文采用方法的正确性.在基于二次场的正演算法基础上,实现了基于L-BFGS的三维反演方法,并对公开的数据集进行了反演.另外,针对大地电磁法的多频率观测特性,采用了基于MPI的分频并行策略对程序进行并行化,可达到接近线性的加速比.Efficient and accurate three dimensional magnetotelluric forward modeling method has attracted increasing attention in recent years. Due to that the source of magnetotelluric is plane wave, the approach that most forward modeling method used is solving the total field directly and imposing two dimensional boundary conditions. In this work, we propose a secondary field approach for three dimensional magnetotelluric forward modeling. We use the response of plane wave of a layered background model as the source term, then we get the partial difference equation that the secondary field satisfied, staggered grid finite difference method is used to solve this equation. Comparison with others result proves the correctness of our method. Based on our forward method, we implemented a three dimensional L-BFGS inversion method and inverted two public datasets. Besides, to utilize the multi-frequency characteristic of magnetotelluric, our code has been parallelized over frequencies using MPI, this approach can achieve near linear accelerate rate.

关 键 词：大地电磁测深法 并行 三维正演 二次场方法 三维反演 

分 类 号：P631[天文地球—地质矿产勘探]