论文部分内容阅读
为改善CSAMT一维反演的实用性,本文以电磁场数值模拟为基础,推导出偶极源激发下频率域电磁反演中的偏导数公式.并以三层水平层状地电模型为例,针对同线装置和赤道装置两种形式,利用扰动法对本文的半解析算法结果进行验证.对比结果表明无论同线还是赤道装置,本文半解析结果和扰动法计算结果拟合程度非常好,验证了偏导数公式推导及程序代码的正确性.进而,分析了CSAMT观测数据对中间薄层参数的灵敏度.灵敏度特征分析表明:CSAMT观测资料对中间低阻薄层比较敏感,对高阻薄层的分辨率较低,但对层厚度,即便是高阻薄层,仍存在较高的灵敏度.频率对层参数的灵敏度有重要影响.实际应用中,应同时考虑资料和参数加权,以提高中间层参数的求解能力.本文的算法不仅有助于CSAMT资料反演解释,同时为地下薄目标层的有效识别提供理论依据.
In order to improve the practicability of one-dimensional inversion of CSAMT, this paper derives the partial derivative formula of electromagnetic inversion in frequency domain under the excitation of dipole source based on the electromagnetic field numerical simulation. Taking the three layered stratiform geoelectric model as an example, The results of the semi-analytical method in this paper are validated by the perturbation method for both the equatorial device and the equatorial device, and the comparison results show that the fitting results of the semi-analytical results and the perturbation methods are very good, The derivation of the partial derivative formula and the correctness of the program code were carried out.Furthermore, the sensitivity of the CSAMT observation data to the intermediate thin-layer parameters was analyzed.The sensitivity analysis showed that the CSAMT data were sensitive to the middle low- The resolution is low, but the layer thickness, even high-resistance thin layer, there is still a high sensitivity.The frequency of the sensitivity of the layer parameters have an important influence.In practice, should also consider the data and parameter weights to improve the middle layer Parameter solving ability.The algorithm in this paper not only contributes to the CSAMT data inversion and interpretation, but also provides a theoretical basis for the effective identification of the target layer of thin underground.