| 并矢格林函数等效源法在钻孔电磁波法中的应用 |
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| 摘 要： | 针对双孔电波法的实际情况,研究无限有耗媒质中,在半波偶极天线激励下,存在导电异常体的散射问题。理论上是根据等效源定理在散射体内引入等效电流,利用并失格林函数建立电场的积分方程并将其化为矩阵方程。在数值计算中,精心设计计算机程序,为提高计算精度,采取小圆柱体作为剖分单元。从物理角度对积分方程奇异点做巧妙的处理。经多次试算,结果令人满意。从而证明本文提出的理论和计算方法的有效性和适用性。
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| 关 键 词： | 钻孔电磁波法 并矢格林函数 积分方程 等效源法 |
APPLICATION OF DYAD GREEN'S FUNCTION EQUIVALENT SOURCE METHOD IN BOREHOLE ELECTROMAGNETIC METHOD |
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| Authors: | Li Chunxiang Chen Zhen Li Shouchun |
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| Institution: | Li Chunxiang Chen Zhen Li Shouchun |
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| Abstract: | The throughboreh-ole electromagnetic method has been proved to be effective for the prospecting of the underground objects. In order to spread the application of this method, and raise efficiency, it is necessary to make further investigation of the relations between the observed electromegnetic data and the characteristics of the scatterers, end to improve the capability of the interpretation for measuring data.The theoritical research of the numerical models using ccmputer will help us to determine which method is the mcst suitable cne end how to improve the existed methods. The aim of this paper is to investigate the scattering problem of a conducting circular cylinder in the unbounded dissipating medium excited by the half-wave dipole antennas of the frequency range from 0.5 to 30M Hz. We introduce the concept of effective electrical current density, from the Maxwell's equation,and construct the integral equations within and outside the Sca-tterer by using the dyadic Green's function, and then convert integral equations into maxtrix equations with dyadic Green's function.The effective current density which produce the out-of-scatterer field is determined from the integral equation of the electrical field within the scatterer. The out-of-scatterer seatering field (in the measuring borehole) is obtained on the basis of the current density. The measured data should be the superposition of the scattering and incident fields (i.e.the total frields). In the numerical calculation, we designed painstakingly the computer program, the circular cylinder is divided into 63 elements arranged in layers according to the consideration of minimum error. The treatment of the strange point of Green's function has our own distinguishing feature. The coincidence of the result of calculation with the practical data shows the effectivity and applicability of the met hod adopted in this paper. |
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| Keywords: | borehole electromagnetic method dyad Green's function integral equation equivalent source method |
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