On sensitivity detection area and analysis of influence factors for semi-airborne transient electromagnetic method
Grounded wire source semi-airborne transient electromagnetic has received much attention for its advantages of large detection depth and high efficiency.However,the theoretical research on this method is still in its preliminary stage.Studying this correlation is crucial for accurately interpreting the data obtained from ground-based transient electromagnetic surveys.This study employs the footprint technique,commonly used in airborne electromagnetics,to investigate the aforementioned issue.Initially,by employing tensor Green's integral,the contribution of discrete current elements beneath the surface to the secondary magnetic field response at the airborne receiving point is derived.Subsequently,an analysis is performed to investigate the distribution of footprint,along with the temporal and spatial evolution patterns of the semi-airborne transient electromagnetic method.Furthermore,the impact of flight altitude and offset distance on the footprint area in the context of semi-airborne transient electromagnetic surveys is examined.The research findings indicate that the temporal characteristics of the footprint are closely related to the diffusion properties of the induction current field in the subsurface,and they are influenced by the relative position of the receiving point.In the early stages,the footprint is primarily concentrated directly beneath the emission source.As the induction current field gradually diffuses towards the direction of the receiving point,the contribution from the subsurface region beneath the receiving point increases gradually.In the later stages,the highest contribution is mainly concentrated on either side of the receiving point,near the near-surface region.The discovery is valuable for semi-airborne transient electromagnetic method based on resistivity imaging.
Semi-airborne transient electromagneticFootprintMain contributing regionsInduced current field
万方数据
维普
