An Improved Helicopter Time-domain EM System for Near Surface Applications

Summary As part of a continued system design strategy aimed at expanding its early-time data, VTEM ET (Early Time) focuses on further improving the system’s capabilities for near surface applications, such as groundwater and environmental. The VTEM ET system improvements include: a) increased receiver bandwidth, b) microsecond resolution of early time channel measurements, and c) shorter transmitter current waveform turn-off. Each of these improvements contributes to an overall increase in the system’s sensitivity to subtle changes in the near-surface geology and improves the accuracy of data models. This is initially demonstrated using 1D synthetic forward and inversion modelling of VTEM ET data compared to the standard VTEM system. To further demonstrate increased sensitivity, inversion results are presented from the Spiritwood aquifer region of North Dakota and are compared against well log lithology.