|
|
|
| Two-dimensional nonlinear conjugate gradient inversion of ZTEM |
| Zhi-Bo XU1, Han-Dong TAN2 |
1. Civil and Transportation College of Beihua University, Jilin 132013, China
2. School of Geophysics and Information Technology, China University of Geoscience (Beijing), Beijing 100083, China |
|
|
|
|
Abstract The ZTEM (Z-Axis Tipper Electromagnetics) is a frequency-domain airborne electromagnetic method that results from natural sources. It has the feature that the vertical component of magnetic field is measured from a moving helicopter platform and the horizontal component of magnetic field is measured at a reference station on the ground. In addition, it has the advantages of deep exploration, fast speed, low cost and large coverage area. This paper realizes the 2D finite difference forward modeling and NLCG inversion of ZTEM. The object of the study is the tipper data. The direct calculation of Jacobian matrix is avoided by solving the "quasi-forward" problem in the inversion process. The stability and reliability of the 2D NLCG inversion of ZTEM tipper data are verified by the trial calculation of synthetic data inversion of theoretical model. A comparison with the inversion result of impedance data of magnetotelluric (MT) TE mode shows that the ZTEM tipper inversion is superior to the MT impedance inversion in the constraint of the lateral boundary of the anomalous body.
|
|
Received: 10 August 2018
Published: 10 April 2019
|
|
|
|
|
|
|
A schematic diagram of two dimensional object model
|
|
The tipper response comparison between the 2D finite difference modeling results and the 3D finite difference modeling results generated from 2D model
|
|
Schematic diagram of single abnormal body model
|
|
Convergence Curve of RMS misfit versus iteration number
|
|
The inversion results of ZTEM tipper data generated by a single abnormal body model
|
|
The inversion results of ZTEM tipper data generated by a single abnormal body model
|
|
Schematic diagram of two abnormal bodies model
|
|
Convergence Curve of RMS misfit versus iteration number
|
|
The inversion results of ZTEM tipper data generated by two abnormal bodies model
|
|
The inversion results of MT tipper data generated by two abnormal bodies model
|
| [1] |
Mackie R L, Madden T R . Three-dimensional magnetotelluric inversion using conjugate gradients[J]. Geophysics.J.Int., 1993,115:215-229.
|
| [2] |
Rodi W, Mackie R L . Nonlinear conjugate gradients algorithm for 2-D magnetotelluric inversion[J]. Geophysics, 2001,1(1):174-187.
|
| [3] |
Lin C H, Tan H D, Tong T . Three-dimensional conjugate gradient inversion of magnetotelluric sounding data[J]. Applied Geophysics (in Chinese), 2008,5(4):314-321.
|
| [4] |
Ward S H . AFMAG—airborne and ground[J]. Geophysics, 1959,24(4):761-787.
|
| [5] |
Ward S H, O’Donnell J, Rivera R ,et al.AFMAG-application and limitation[J]. Geophysics, 1966,31(3):576-605.
|
| [6] |
Lo B, Zang M. Numerical modeling of Z-TEM (airborne AFMAG) responses to guide exploration strategies [C]// 78th International Exposition and Annual Meeting, SEG, Expanded Abstracts, 2008, 1098-1102.
|
| [7] |
Labson V F, Becker A, Morrison H F , et al. Geophysical exploration with audiofrequency natural magnetic fields[J]. Geophysics, 1985,50(4):656-664
|
| [8] |
吴頔 . 二维及三维倾子响应和异常体识别[D]. 长沙:中南大学, 2012.
|
| [8] |
Wu D . 2D and 3D tipper response and abnormal body recognition[D]. Changsha: Central South University, 2012.
|
| [9] |
余年, 王绪本, 阚瑷珂 , 等. 倾子和视倾子的研究及在断裂解释中的应用[J]. 工程地物学报, 2007,4(4):275-281.
|
| [9] |
Yu N, Wang X B, Kan Y K , et al .Research on tilter and apparent tilter and its application in fracture interpretation[J]. Geophysical and Geochemical Exploration, 2007,4(4):275-281.
|
| [10] |
林昌洪, 谭捍东, 佟拓 . 倾子资料三维共轭梯度反演研究[J]. 地球物理学报, 2011,54(4):1106-1113.
|
| [10] |
Lin C H, Tan H D, Tong T . 3D conjugate gradient inversion of dipper data[J]. Applied Geophysics, 2011,54(4):1106-1113.
|
| [11] |
Holtham E, Oldenburg D W . Three-dimensional inversion of ZTEM data[J]. Geophysical Journal International, 2010,182:168-182.
|
| [12] |
Holtham E, Oldenburg D W. Three-dimensional inversion of MT and ZTEM data [C]// 80th Ann Internet Mtg, SEG,Expanded Abstracts, 2010: 655-659.
|
| [13] |
Wang T, Tan H D, Li Z Q , et al. 3D finite-difference modeling algorithm and anomaly features of ZTEM[J]. Applied Geophysics (in Chinese), 2016,13(3):553-560.
|
| [14] |
王绪本 . 二维大地电磁测深资料处理与反演解释方法研究[D]. 成都:成都理工大学, 2002.
|
| [14] |
Wang X B . Research on processing and inversion interpretation method of two-dimensional magnetotelluric sounding data[D]. Chengdu:Chengdu University of Technology, 2002.
|
| [15] |
Madden T R . Transmission systems and network analogies to geophysical forward and inverse problems[M]. ONR Technical Report, 1972: 72-3.
|
| [16] |
胡文宝, 苏朱刘, 陈清礼 , 等. 倾子资料的特征及应用[J]. 石油地球物理勘探, 1997,32(2):202-213.
|
| [16] |
Hu W B, Su Z L, Chen Q L , et al. Characteristics and application of tilter data[J]. Oil Geophysical Prospecting, 1997,32(2):202-213.
|
| [17] |
陈小斌, 赵国泽, 詹艳 , 等. 磁倾子矢量的图示分析及其应用研究[J]. 地学前缘, 2004,1(4):626-636.
|
| [17] |
Chen X B, Zhao G Z, Zhan Y , et al. Analysis of tipper visual vectors and its application[J]. Geoscience Frontiers, 2004,1(4):626-636.
|
| [18] |
陈清礼, 胡文宝, 李金铭 , 等. 埋藏球体的倾子响应特征分析[J]. 石油天然气学报, 2007,29(3):75-78.
|
| [18] |
Chen Q l, Hu W B, Li J M , et al. Analysis of tipper response characteristics of buried sphere[J]. Journal of Oil and Gas Technology, 2007,29(3):75-78.
|
| [19] |
马为 . MT 二维正演中辅助场计算新方法研究[R]. 中国地震局地质研究所, 2007.
|
| [19] |
Ma W . A new method for calculating auxiliary field in MT two-dimensional forward modeling[R].Institute of Geology, China Earthquake Administration, 2007.
|
| [20] |
陈小斌 . MT二维正演计算中地形影响的研究[J]. 石油物探, 2000,39(3):112-120.
|
| [20] |
Chen X B . Research on terrain effect in MT two-dimensional forward modeling[J]. Oil Exploration, 2000,39(3):112-120.
|
|
|
|
