Downhole EM / MMR

High-powered, deep search technology produces highest quality downhole data.

Gap GeoPhysics’ Downhole systems combine Gap GeoPak High Powered EM Transmitters and EMIT DigiAtlantis Probes, resulting in the most powerful downhole EM systems currently available. They are ideally suited to the detection of subtle or deep conductors.

DigiAtlantis System

  • 3-component Fluxgate B-field sensor
  • Simultaneous acquisition of all components
  • Calculation of Downhole magnetics and Hole Trajectory
  • Real time viewing of data for improved data quality

High Powered Transmitter System

  • High currents produce better quality data
  • Rapid acquisition times and reduced survey cost
  • Increased detection radius
  • Increased depth of investigation

Downhole ElectroMagnetics (DHEM) provides greater spatial resolution of closely spaced conductors than surface or airborne geophysical surveys.


  • The DHEM technique is ideally suited for detecting conductive massive sulphide mineralisation, in particular nickel sulphide bodies.
  • The Downhole MagnetoMetric Resistivity (DHMMR) technique is ideally suited for detecting narrow ribbon shaped and/or poorly conducting mineralisation such as sphalerite rich bodies.


Sensors3-component fluxgate (EMIT DigiAtlantis) or 3-component coil (Geonics BH43-3)
WinchesAusLog 600-4 (600m), AusLog 2000-4 (2000m) or DGRT Laminar (2000m)
Tx SynchronisationGPS 1PPS pulse or clock
TransmittersGap GeoPak HPTX-80/80 Transmitters
Base FrequencyTypically 0.125Hz to 2.0Hz
Current200A for a 600m x 600m loop
140A for a 1000m x 1000m loop,
using 35 sq mm wire
ReceiverEMIT DigiAtlantis