40LGR-1000 Combination Gamma SP SPR Logging Tool


The 40LGR-1000 Gamma, SP, and SPR probe is the most fundamental probe used in hydrogeological studies, lithology work, uranium exploration, and general borehole formation data.  The totally digital probe combination measures single point resistance, self-potential, and natural gamma in two borehole passes.  This probe operates with the Matrix digital logger and uses the latest LoggerSuite logging software.

The 40LGR-1000 is a standalone tool. Unless identifying screened intervals and joints, single point resistance and self-potential measurements are designed for surveying open (uncased) fluid-filled boreholes. Gamma measurements can be taken in any borehole environment.


  • Bed boundary analysis
  • Facies changes
  • Quantitative geological formation properties
  • Identification of Hydrostratigraphic units
  • Aquifer thickness and Water quality
  • Hydrocarbon intervals, Ore body zones, In-situ Uranium assay
  • Fluid contaminant monitoring, Soil horizons, Grain size estimation

Operating Conditions

Natural Gamma can be used in any borehole conditions.

For SP and SPR measurements, the following conditions apply:

Borehole Fluid
[X] Water
[X] Mud
[_] Dry

[X] Uncased
[_] PVC Borehole
[_] Steel

[_] Required
[X] Not Necessary

Isolation Bridle
[X] Required for
[_] Not Necessary

Features & Benefits

  • Can log resistance and gamma measurements with one tool.
  • Wide range of applications- from hydrogeology to mining to hydrocarbons
  • Ultra slimline and easy one-person operation
  • Fully downhole digital, functions easily on longer wirelines

Specifications – Metric/English

Specification Metric Imperial
Diameter 43 mm 1.7″
Length 1.12 m 44″
Weight 4 Kg 8.8 lbs.
Max. Temp. 70ºC 158ºF
Max. Pressure 200 bar 2900 psi


Natural Gamma Sensor: Sodium Iodide Crystal
Gamma Range: 0 to 100,000 cps/API
Gamma Accuracy: 1%
Gamma Resolution: 0.02%

Sensors: Stainless steel electrodes
SPR Range: 0 to 10,000 Ohms
SPR Accuracy: 1%
SPR Resolution: 0.02%

SP Range: ± 1,500 mVDC
SP Accuracy: 1%
SP Resolution: 0.04%


Data Sheet
User Guide

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