网格尺寸及边界对大地电磁有限元正演精度的影响  

EFFECTS OF GRID SIZE AND BOUNDARY ON MT FORWARD MODELING USING FINITE ELEMENT METHOD

作　　者：吴娟[1] 席振铢[1] 王鹤[1] 

机构地区：[1]中南大学地球科学与信息物理学院,湖南长沙410083

出　　处：《物探化探计算技术》2012年第1期27-32,4,共6页Computing Techniques For Geophysical and Geochemical Exploration

基　　金："十一五"国家科技支撑计划项目(2006BAB01B07)

摘　　要：大地电磁正演的精度对后续反演意义重大。决定大地电磁有限元正演精度的因素,主要有插值函数、方程组的求解误差,以及网格的剖分程度。而网格剖分的合适与否,为有限元的求解提供了先决条件。因此,从边界条件和横向网格以及纵向网格三方面,讨论了网格剖分对大地电磁正演精度的影响。经研究表明,对于一维和左右对称的二维介质,左右和下边界都无需放置在无穷远处,并且横向网格对精度影响不大。而由于纵向网格与近地表的最小趋肤深度密切相关,所以地表网格不得大于1/4个趋肤深度。The accuracy of the magnetotelluric(MT) forward modeling takes an important part in the inversion.The main factors that determine the accuracy of MT forward modeling using finite element method(FEM) are interpolation function,error of solving linear equations and grid size.However,that grid size is appropriate or not provides a prerequisite for fem simulating.According to its borders and horizontal and vertical grid length,it was discussed their effects to MT modeling.The results shows that the left,right and the lower boundary are not necessary to place at infinity and the horizontal grid has little effect on accuracy for one-dimensional or good symmetric two-dimensional media and that vertical grid is closely related to the smallest skin depth and it can not larger than 1/4 skin depth on the earth surface.

关 键 词：大地电磁 网格 边界 精度 

分 类 号：P631.325[天文地球—地质矿产勘探]