2D inversion of frequency-domain electromagnetic data generated by line current source
首发时间:2015-11-25
Abstract:The inversion of electromagnetic data is an inherently non-unique and unstable problem due to the data noises and incomplete data coverage, which means different geo-electrical models could fit the observed data at the same level. A stable solution of an ill-posed inverse problem can be obtained by the regularization methods in which some desired structure are imposed to stabilize the inverse problem. We have developed an algorithm to invert frequency-domain electromagnetic data generated by a line current source for a 2D model of the earth. To stabilize the inversion, we adopt a smoothness-constraint approach for the model parameters and adjust the regularization parameter objectively using a adaptive regularization parameter technique. For calculating the sensitivities using any of the accurate methods will be very time-consuming, we applied the adjoint-equation approximate method. By means of the numerical examples using synthetic data, we have demonstrated that the inversion method can be effectively to reconstruct the subsurface resistivity structure.
keywords: frequency-domain electromagnetic line current source 2D inversion smoothness-constrained
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基于线源激励的频率域电磁数据二维反演
摘要:由于实测数据包含噪声和其固有的不完备性,决定了频率域电磁测深数据在数学计算上是一个非唯一解的、不稳定的问题,这就意味着不同的地电模型可以拟合在同一剖面上的观测数据。这种问题可以通过给定加权的正则化方法使得病态反演问题变为稳定。本文实现了频率域线源CSAET法剖面的二维反演计算。为了使反演过程稳定,采用了模型参数的平滑度约束的方法,并使用自适应正则化参数技术调整了反演正则化参数。并且在计算过程中利用了伴随方程近似计算方法,减少了计算灵敏度的耗时。数值计算表明,利用合成的数据可以得到精确的反演结果。
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No.4662949257813144****
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