Mount Sopris Instruments

40GRP

Gamma + Short/Long Resistivity + SP/SPR

Standalone combination probe utilizing isolation bridle

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Description

The 40GRP-1000 standalone probe is ideal for slimline, one-pass hydrogeological studies, lithology work, uranium exploration, and general borehole formation data. This totally digital probe measures 16, 64 inch (0.4, 1.6 meter) normal resistivity, single point resistance (SPR), spontaneous potential (SP), and natural gamma. It operates with the newest LoggerSuite digital logging system and software.

The normal resistivity measurements, single point resistance, and spontaneous potential measurements are designed for surveying open (uncased) and fluid-filled boreholes. Gamma measurements can be measure in any borehole environment.

Applications

  • 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

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40GRP — Gamma + Short/Long Resistivity + SP/SPR — Standalone combination probe utilizing isolation bridle

Technical Specifications

Accessories

  • Isolation bridles
    • QL40-ISQL (QuickLink connection)
    • QL40-IS4 (GO4 probe top)
  • Calibration box (P.N. 17 202 096/TB001)
    • Normal Resistivity
    • Spontaneous Potential
    • Induced Polarization

Tool

  • Diameter: 43mm (1.7”)
  • Length: 2.21m (87”)
  • Weight: 8.8kg (19.5 lbs)
  • Temp: 0 - 70°C (32 - 158°F)
  • Max. Pressure: 200bar (2900psi)

Resistivity sensor

  • Sensor: stainless steel electrode
  • Resistivity range: 0,1 to 100.000 Ohm.m.
  • Resistivity accuracy: depends on measurement range
    • Below 1% of measured value from 1 to 5.000 Ohm-m
    • Below 5% of measured value from 5.000 to 50.000 Ohm-m
  • Resistivity resolution: below 0.04% of measured value
  • SPR range: 0,1 to 100.000 Ohm
  • SP range: ±18V
  • SP accuracy: ±2.5mV
  • SP Resolution: 0.5mV

Natural gamma sensor

30.875” (22.2mm) x 3” (75.6mm) NaI (Ti) scintillation crystal

  • Gamma range: 0 to 100,000 cps/API
  • Gamma accuracy: 1%
  • Gamma resolution: 0.02%

Operating conditions

  • Cable type: Mono, multi-conductor, coax
  • Compatibility: Scout Pro / Opal (Scout / Bbox / Matrix)
  • Digital data transmission
  • Telemetry: Variable baudrate telemetry according to cable length/type & surface system
  • Logging speed: 5-6 m/min recommended
  • Centralisation: Not required
  • Borehole fluid: Gamma in any conditions Resistivity in uncased, fluid-filled boreholes

Principle of measurement

An electric current is injected into the formation from the current electrode. Potentials due to this current flow are measured on various current electrodes on the probe with respect to a voltage reference electrode located at the top of the isolation bridle. The spacing between the current and individual measure electrode determines the depth of investigation of the measurement. The voltage measurements are proportional to the resistivity of the formation.

Measurement features

  • N16 : 16” normal resistivity in ohm-m (short normal)
  • N64 : 64” normal resistivity in ohm-m (long normal)
  • SPR : single point resistance in ohms
  • SP : spontaneous potential in mV
  • GR : total gamma counts in cps/API
40GRP