Off-Hole Anomaly Detection
Off Hole Anomaly Detection applies to deep boreholes (> 200m) as well as small off-hole targets which cannot be easily detected from surface. These measurements can be made in vertical boreholes down to 2000m depth as well as in horizontal or upward inclined boreholes up to 800m.
For the definition of magnetic off-hole anomalies we apply magnetic vector measurements in boreholes using 3 Axis fluxgate and 3 axis inclinometer systems.
Electromagnetic off-hole anomalies, due to massive sulfide bodies for example, can be detected by using the electromagnetic probes BH43-3 (GEONICS) and the Digital Atlantis probe (EMIT). This is done by using single holes (vertical to horizontal) or a group of boreholes with transmitting loops on the surface or in an underground mine.
Different array types like gradient and pole-dipole can be applied. The results can also be modeled in combination with surface data.
terratec Geophysical Services uses customised hole-to-hole Induced Polarization methods in combination with the High Resolution Induced Polarization method (HIRIP) from the surface down to 1500m depth.