物理学报2017，Vol.66Issue(13)：311-325,15.DOI:10.7498/aps.66.139102
用数值模式匹配算法高效仿真轴对称型散射体海洋可控源电磁响应
Efficient simulation of marine controlled source electromagnetic responses for axisymmetric scatter by using numerical mode matching approach
摘要
Abstract
Horizontal disk, sphere, and spherical crown are a very important type of scatter in geophysics research. In the marine environment, a disk-like scatter can be used to describe several resistive targets, e.g., basaltic sills and stratigraphic hydrocarbon reservoirs while spherical crown can be used to approximately depict the topography of interface for basement rock. This type of scatter has characteristics of axisymmetrical distribution of the conductivity. If some approaches can be established to efficiently simulate the marine controlled source electromagnetic (MCSEM) response to this scatter, it will be meaningful to investigate the nature of MCSEM responses in complex formation and to build appropriate method of processing and explaining MCSEM data. In this paper, the resistive scatters are approximated by one or several horizontal concentric disks with different radii and thickness values, based on the axially symmetrical spatial distribution of conductivity. Then, a combination of these concentric disks with air, sea water and surrounding beds will construct a horizontally stratified inhomogeneous formation with common axis-center, whose spatial distribution of conductivity is layered in the vertical direction and axisymmetric in the horizontal direction. Based on the approximations mentioned above, the computation of MCSEM response excited by horizontal electrical dipole (HED) located at the z-axis is entirely transformed into two axially symmetrical problems for the Fourier harmonic components of the electromagnetic (EM) fields. The differential operators about the horizontal magnetic components and transformation of horizontal electrical components and other EM components from horizontal magnetic components are derived. Then, the numerical mode matching approach is extended to the simulation of the EM field and three-dimensional (3D) MCSEM responses excited by the HED in the formation. The procedure for solving the EM field is presented. The semi-analytic solution of EM field in the whole space is obtained to efficiently and numerically model MCSEM response in the complex formation. Finally, the efficiency and accuracy of the present method are demonstrated numerically. The characteristics of 3D MCSEM responses in three different cases are further investigated.关键词
海洋可控源电磁/轴对称散射体/数值模式匹配法/半解析解Key words
marine controlled-source electromagnetic method/axisymmetric scatter/numerical mode matching approach/semi-analytic solution引用本文复制引用
林蔺,焦利光,陈博,康庄庄,马玉刚,汪宏年..用数值模式匹配算法高效仿真轴对称型散射体海洋可控源电磁响应[J].物理学报,2017,66(13):311-325,15.基金项目
国家自然科学基金(批准号: 41574110)和国家高技术研究发展计划重大项目(批准号:2012AA09A20103)资助的课题. Project supported by the National Natural Science Foundation of China (Grant No. 41574110) and the National High-tech R & D Program, Major Project, China (Grant No. 2012AA09A20103). （批准号: 41574110）
