3D Joint Inversion of Borehole, Surface, and Airborne Magnetic Anomaly

Abstract

The surface magnetic anomaly provides excellent horizontal resolution, the three-component borehole magnetic anomaly offers excellent vertical resolution, and the aeromagnetic anomaly contains valuable information about deeper and larger magnetic sources. The advantages features of the three types of data can be combined to improve inversion resolution and reduce the nonuniqueness through the joint inversion. Currently, research primarily focuses on borehole–surface joint inversion, with the aeromagnetic anomaly seldom integrated into the joint inversion system, resulting in underutilization of its rich information. Furthermore, existing research findings on borehole–surface joint inversion primarily offer qualitative insights into the improvement in vertical resolution due to borehole magnetic anomalies. However, further investigation is required to understand the varying degrees of improvement brought about by different borehole quantities, positions, and distributions. To fully exploit the advantages of the three data and achieve higher inversion resolution, we propose a 3D joint inversion algorithm incorporating borehole, surface, and airborne magnetic anomalies. Through synthetic model experiments, we initially assess the actual enhancement brought by the aeromagnetic anomaly on inversion quality and discover effective ways to leverage its advantages. Subsequently, we investigate the degree of improvement in inversion quality resulting from different combinations of boreholes, summarizing optimal borehole selection methods. Finally, we apply the algorithm to a real mining area, validating its practicality by comparing the inversion results with drilled rock cores. Our research indicates that the proposed method yields inversion results with both high horizontal and vertical resolution, faithfully representing the physical properties of shallow-small and deep-large magnetic sources.