重力向下延拓的迭代法对比分析研究

Comparative analysis on the iterative methods for downward continuation of gravity field

向下延拓是位场数据处理和解释的基本方法,但其不适定性导致计算结果稳定性差。近年来,迭代法在提高向下延拓计算稳定性和计算精度方面上的优势备受重视。为比较各种迭代法的优缺点,对积分迭代法、泰勒级数迭代法和补偿法进行了对比分析研究。在模型试算的基础上,将三种方法应用到了江西相山铀矿田重力数据处理之中。研究表明,三种迭代法的迭代通式具有较强的相似性,只是选取的初始滤波算子不同,但初值滤波算子选取的合理性直接决定着迭代法对低频成分的转换能力和高频成分的压制能力。补偿法在向下延拓计算中具有更高的计算精度和更强的计算稳定性,因此选择补偿法具有更好的实际应用价值。

Downward continuation is a basic method for data processing and interpretation,but its ill-posedness makes the calculation unstable.In the aspect of improving the computational stability and accuracy of downward continuation,the iterative methods have been highly regarded due to their good application effect in recent years.This paper focuses on basic principles and filter characteristics of integral-iteration method,Taylor series iteration method and compensation method,and comparative analysis on continuation effect of different iterative methods using model test and application of gravity anomaly over Xiangshan orefield in order to compare the advantages and disadvantages of various iterative methods.The results showed that the general formulas of different iterative methods are very similar,but the initial filter operators are different and the rationality of the initial filter operator directly determine the transformative capacity of low frequency useful signal and the ability of suppressing high frequency interference.The model test and application indicate that the compensation method has higher accuracy and better computational stability for downward continuation.Therefore,selecting the compensation method can obtain better results in the real data processing.