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Probes

RG Focussed Induction Probe

Focussed Induction Probe

The focussed induction probe produces accurate formation conductivity logs even in dry or plastic-lined boreholes. The probe coil spacings are optimised to achieve high vertical resolution and a deep radius of investigation, with minimal borehole influence when logging in conductive-fluid-filled holes.

PRINCIPLE OF MEASUREMENT
An oscillating high-frequency magnetic field from a transmitter coil in the probe induces an alternating electrical current within the surrounding formation proportional to its electrical conductivity. This current, in turn, induces voltages within the receiver coils. These are phase discriminated and measured. These voltages are proportional to the formation conductivity. Additional focussing coils minimise the contribution of the borehole signal.

   
FEATURES
Formation conductivity measurement in wet/dry boreholes or through plastic casing
Focussed measurements almost eliminates borehole signal
PSD (phase-sensitive detector) discriminates between magnetic susceptibility and conductivity signals
Highly stable measurement is almost independent of temperature
Option of natural gamma for correlation
MEASUREMENTS
Formation conductivity
Natural gamma (optional)
APPLICATIONS
Water Indicator of permeable zones and porosity
Formation-water salinity
Long-term well monitoring
Engineering
Minerals
Ore identification and quality
Correlation
Other Indication of hydrocarbons
OPERATING CONDITIONS
Borehole type open/ plastic or grp cased, air/water filled
Centralisation none; fin standoff recommended
SPECIFICATIONS
Diameter 38mm
Length 2.15m
Weight 9kg
Max. temperature 70ºC (extended range available)
Max. pressure 20MPa (extended range available)
Number of coils 4
Operating frequency 39kHz
Effective TX-RX spacing 500mm (20in)
Resolution 1mS/m
Conductivity range 2 to 3000 mS/m
Natural-gamma detector 50mm x 25mm NaI(Tl) scintillation crystal (larger sizes available)
SALES INFORMATION
Probe
25 060 000 Focussed Induction probe with calibration ring
25 061 000 includes natural gamma
Accessories
23 001 000 Fin stand-off
20 070 000 Natural-gamma API calibrator without source
30 010 000 3.7MBq 137Cs source for natural gamma calibrator

 

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  Robertson Geologging Ltd, Deganwy, Conwy, LL31 9PX
Robertson Geologging (USA) Inc, 11115 Mills Road, Suite 117, Cypress, Texas 77429, USA