摘要
大地电磁(Magnetotelluric,MT)正演是其资料解释的基础,也是认识地球介质响应特征的重要手段.磁化率和电阻率是影响MT响应的两个主要物性参数,真实固体地球介质电阻率各向异性现象普遍存在且铁磁性等物质的磁化率显著.而当前成熟的MT资料解释技术仍局限于各向同性介质、电阻率单一参数.本文从Maxwell方程组出发,推导了磁化率、电阻率主轴各向异性均匀半空间和层状介质的视电阻率及相位的解析表达式.然后,通过两个不同类型模型的计算对比,验证了算法的正确性.最后,对典型模型进行计算,结果表明某些情况下磁化率的影响不可忽略,对于低阻地层,当其电阻率与相对磁导率的乘积大于围岩的电阻率时,其视电阻率将表现为高阻.本文开发的正演算法,有助于认识磁化率、电阻率主轴各向异性时的MT响应特征,也可为后期二维、三维正演提供参考对比.
The Magnetotelluric(MT)method is an important geophysical method that has been widely used in many areas such as mineral resources survey,exploration of oil&gas and the investigation of deep Earth.MT forward modeling is the basis of data interpretation,and it is also an important method to understand the response characteristics of the earth.On the one hand,magnetic susceptibility and resistivity are the two main physical parameters that affect the MT’s response.On the other hand,the earth is anisotropic and the ferromagnetic materials’susceptibility is obvious which cannot be ignored.Therefore,it is important to understand how MT modeling be performed in resistive anisotropic and magnetic medium.However,mature MT data interpretation technology is still limited to isotropic resistive medium.For magnetic and axial resistive anisotropic half-space and layered-medium,we therefore obtained the analytical solutions of the apparent resistivity and phase based on Maxwell’s equations.Then,this method’s correctness is verified by an resistive&magnetic model and an axial anisotropic resistive model,respectively.Then,four different typical models are computed,and the results show that the susceptibility’s influence cannot be ignored in some cases.Especially,for a magnetic layer with a lower resistivity,its apparent resistivity may even behave as high resistivity due to the influence of a high susceptibility.The method developed in this paper can help to understand the MT’s responses of the magnetic and axial resistive anisotropic medium,and can also provide a reference for 2 D or 3 D modeling algorithms.
作者
陈琳
肖调杰
刘剑
郑翾宇
刘杰
王赟
CHEN Lin;XIAO TiaoJie;LIU Jian;ZHENG XuanYu;LIU Jie;WANG Yun(Parallel and Distributed Processing Laboratory,National University of Defense Technology,Changsha 410073,China;Laboratory of Software Engineering for Complex Systems,National University of Defense Technology,Changsha 410073,China;School of Geophysics and Information Technology,China University of Geosciences,Beijing 100083,China)
出处
《地球物理学进展》
CSCD
北大核心
2022年第6期2373-2380,共8页
Progress in Geophysics
基金
国家自然科学基金“超大规模多层级并行大地电磁三维磁化率、电导率各向异性正演”(42104078)
国家重点研发计划“E级计算可扩展高效能并行算法及算法库”(2017YFB0202104)联合资助。
关键词
大地电磁
一维正演
解析解
磁化率
各向异性
Magnetotelluric(MT)
1D modeling
Analytical solutions
Magnetic susceptibility
Anisotropy
