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ELTG-LU (Logging tool)

Model id: Robertson Geologging Electric Logging Probe with natural gamma and temperature


  • electric rock resistivity, shallow penetration
  • electric rock resistivity, deep penetration
  • spontaneous/self potential
  • temperature
  • total natural gamma

Purpose: shallow, medium and deep penetrating resistivity measurements with self-potential (SP) and natural gamma

Description: The electric log is the classic water-well combination probe combining shallow, medium and deep penetrating resistivity measurements with self-potential (SP) and natural gamma. The down-hole probe is equipped with electrodes, measurement electronics and an insulated bridle. A low-frequency bi-directional electric current from a source electrode on the probe returns through the formation to the cable armour above the bridle. Potentials due to this current flow are measured on various sense electrodes on the probe with respect to a voltage-reference ‘fish’ normally located at the surface. The spacing between the source and individual sense electrode determines the depth of investigation of the measurement. These measurements are converted to apparent formation resistivities within the probe and digitally transmitted to the surface. The SP is a voltage measurement between a non-polarising down-hole electrode and a reference ‘fish’ at the surface. Our probe is also fitted with a temperature sensor.

Characteristics: 16” Normal resistivity; 64” Normal resistivity; Single-point resistance; Self-potential SP; Temperature; Natural-gamma detector: 50 mm x 25 mm NaI(Tl) scintillation crystal


Vertical resolution:0.010 m
Typical logging speed:5.00 m/min
Maximum pressure:33.0 MPa
Maximum temperature:125℃
Required boreholefluid:
conductive liquidThe borehole has to be filled with a conductive liquid.
Type of datatransfer:
cableData are transferred in real time via a cable.
Required type of logging cable:
4 conductorA logging cable with 4 conductors.
Required cablehead:
GO4Connector according to GO 4 standard (4 conductors).
Implement search on winches with this cable head.
Type of signal:
digitalDigital signal transmission.
Acquisitionsystem (recommended):RG-LU
Length:2.70 m
Maximum diameter:0.044 m
Weight:9.8 kg
Belongs to toolstring:
standaloneA stand alone tool that cannot be integrated in a tool string.
Usage conditons:Commercial usage allowed/welcome.
Additional usage conditions:Logging as service by Lund University

Operator and contact:

Operator:Lund University, Engineering Geology
Contact person:Per-Gunnar Alm
Telephone:+46 462228992
Address: John Ericssons väg 1
223 63 Lund, Sweden

End of I-EDDA database record