MAPPING BURIED AQUIFERS WITH HTEM IN THE FORT MCMURRAY, ALBERTA REGION

摘要

Helibome time-domain electromagnetic (HTEM) systems have proven to be effective tools in mapping sub-surface resistivity, particularly in the realm of mineral exploration. One such HTEM system is VTEM (Versatile time-domain electromagnetic). The recent implementation of full waveform technology to VTEM expands the system's bandwidth to measure data as early as 18 microseconds after the waveform's turn-off which substantially improves the system's ability to resolve resistivity contrasts in the near-surface. This is demonstrated on the Aspen Block, near Fort McMurray, Alberta. This area provided a useful setting in mapping near-surface resistivity variations specifically the location and geometry of the Pemmican Valley aquifer. The VTEM results over the Pemmican Valley aquifer are compared to ground DC resistivity to determine the capability of full waveform VTEM in mapping the resistivity of the near surface. The VTEM results mapped the location of the Pemmican Valley aquifer within the Aspen Block accurately and identified an additional, previously unknown, aquifer located nearer to the surface. The VTEM inversion results defined the edge of the Pemmican Valley aquifer much more decisively than the ground DC resistivity result which indicates higher lateral and vertical resolution to resistivity variations.