MODULUS INVERSION OF THREE-COMPONENT BOREHOLE MAGNETIC DATA
OU Yang1, LIU Tian-you2, GAO Wen-li1, FENG Jie1, QIU Li-quan1
1. Institute of Geophysical and Geochemical Exploration, CAGS, Langfang 065000, China;
2. Institute of Geophysics and Geomatics, China University of Geosciences, Wuhan 430074, China
It is usually necessary to consider the magnetization direction of the magnetic body in the interpretation of three-component borehole magnetic data; however, it is rather difficult to determine the magnetization direction under the strong effect of remnant magnetization or demagnetization. The modulus of magnetic anomaly is not dependent or insignificantly dependent on the magnetization direction, and modulus can be calculated directly by using three-component borehole magnetic data. The authors hence tried to inverse the model parameters with the modulus of three-component borehole magnetic data. First, the value of the modulus was calculated by using three-component borehole magnetic data. Then, the geometrical and magnetic parameters of 2D tabular body and vertical cube were inversed with the modulus data. Finally, this method was applied to the borehole magnetic data of an iron ore mine in Xinjiang. The results show that the modulus inversion result is less influenced by magnetization direction when magnetization direction is unknown or inaccurate; the modulus inversion is superior to the traditional inversion using single-component Za and receives good geological results.
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