Analysis of transient electromagnetic response for the borehole to airborne survey mode

This paper proposes a novel borehole to airborne survey mode for electromagnetic method by integrating the advantages of borehole excitation and airborne observation, which is applicable to the exploration of oil and gas reservoirs. The new approach is expected to offer potential exploration benefits such as large depth penetration, wide coverage area, high precision, and efficiency. Currently, the transient electromagnetic method (TEM) in the borehole to airborne survey mode has not been implemented domestically or internationally, lacking theoretical guidance for equipment development and exploration operations. This paper focuses on the analysis of electromagnetic response characteristics of the borehole to airborne TEM using the vertical electric source in the case of the vertical well condition. The characteristics including induced current diffusion, spatial distribution of multi-component electromagnetic responses, and signal attenuation at different measuring points, are investigated. The study identifies the optimal electromagnetic field components for observation, discusses the technical challenges and feasibility of detection equipment. In summary, the findings of this paper provide essential theoretical groundwork for advancing the new method in terms of detection equipment, operational techniques, data processing, and interpretation.