利用积分方程法的大地电磁三维正演

Three Dimentional Magnetotelluric Forward Modeling Using Integral Equation

摘要:

利用积分方程法实现了均匀导电半空间三维大地电磁响应的数值模拟。求取张量格林函数积分时,采用二次剖分算法解决计算中奇异值问题,对于含有贝塞尔函数的积分项,利用结合连分式展开的高斯求积代替常规的快速汉克尔变换方法,确保了张量格林函数的正确计算并提高了计算精度。最后通过数值模拟结果的对比及模型试算验证了算法的正确性,所实现的三维大地电磁数值模拟算法为理论研究三维地电构造的大地电磁响应的分布规律提供了有效的工具,也为研究三维反演算法奠定了基础。

Abstract:

Using integral equation method, the numerical algorithm of 3D magnetotelluric responses in homogeneous half-space is realized. While calculating tensor Green~ functions , the algorithm of secondary division is adopted to solve the singular problem. The Gaussian quadrature and continued fraction is adopted to calculate the integral with Bessel function. This method not only can ensure the right calculation of tensor Green＇s functions but also can get high precision. The correctness of algorithm has been proved by model comparing and analyse. This efficient algorithm will help to study the distributing laws of 3D magenetotelluric responses and to setup basis for reaserch of 3D inversion.