Research On Reduction Of Aeromagnetic Anomalies By Means Of Equivalent Source Technology

Magnetic data is needed to be at a certain plane or arbitrary for further processingand interpretation. But in aeromagnetic surveying, because of the limitations of aircraftperformance and the measuring equipment, the observed surface is probably not the idealsurface wanted, so the altitude correction must be carried out before further processingand interpretation.There are two main ways to do altitude corrections, based on discrete data (flightline) and grid data. According to the particularities of the data, errors are unavoidablewhile gridding discrete data, so the altitude correction methods based on grid data (witherrors) are not accurate enough. Besides, most of the altitude correction methods based ondiscrete data are presently just mathematical ones and not specific to the particularities ofaeromagnetic data, which could cause great errors in the results and make the methodsnot very satisfactory algorithms, especially for the data obtained from very mountainousareas where the flying surface is generally variable.To address the above problems, we present a new approach for altitude correction asan inversion for the distribution of equivalent sources which can achieve high precisionaltitude corrections based on discrete aeromagnetic data.The main work and achievements in this graduation design are as follows:(1) We have taken deep researches on the popular and widely used continuationtechnology, such as interpolation–iteration method, single layer method and dipole layermethod. Based on deep researches on the placement of the equivalent sources anddesigned multi-layer dynamic placement, which can make the altitude correction resultachieve high precision.(2) To improve the efficiency and save memory space, we have designedoverlapping of the sliding data window to solve the efficiency and the memory spaceproblems by avoiding the calculation of large amount of data. And we have taken deepresearches on the affection of different equivalent source models.(3) Model data is used to test the quality of the methods we presented in this paper,according the comparison with the results of other widely used reduction methods, theresult has shown the high precision.(4) Based on the researches and the achievements, reduction software is developed.Multi-Thread technology is used to improve the efficiency. According to theparticularities of aeromagnetic data, an algorithm is designed to extract and separate thesurvey lines.