磁异常和梯度的频率域三维成像方法

三维反演在磁数据定量解释中具有重要作用。常用的空间域三维反演方法通常需要大量的正演和反演计算,因此对大规模数据的反演效率较低。三维成像是另一种定性和定量解释磁数据的重要方法。文中给出了一种磁异常与梯度三维成像的频率域迭代方法,该方法可以提高成像效率,适用于大规模数据的快速成像。笔者推导了磁总场异常和异常梯度频率域正演公式和成像公式,并将一种深度尺度因子引入成像公式中,提高了深度精度;笔者采用了迭代优化算法,减小了拟合误差,进一步提高了成像精度。通过理论模型数据试验和中国新疆某金属矿床实测数据,验证了本文方法的有效性、可行性。

3-D imaging of magnetic anomalies and gradients in the frequency domain

3-D inversion plays an important role in the quantitative interpretation of magnetic data. However, the commonly used space-domain 3-D inversion algorithms usually require a large number of forward modeling and inversion calculations. Hence, the inversion based on a large-scale data is usually inefficient. 3-D imaging is another significant algorithm for the qualitative and quantitative interpretation of magnetic data. This paper implements a frequency-domain iterative approach for 3-D imaging of magnetic anomalies and gradients, which can improve imaging efficiency and is suitable for rapid imaging of large-scale data. The frequency-domain forward formulae and imaging formulae of magnetic total field anomaly and magnetic gradients are derived in this paper. A depth scaling factor is added to the imaging formulae to significantly improve the depth resolution. In order to reduce the fitting error and improve the imaging accuracy, this paper adopts an iterative optimization algorithm. The effectiveness and feasibility of the presented approach were verified by the synthetic data and real data from a metallic deposit area in Xinjiang.