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Probes

RG Dual Focussed Induction Probe

Dual Focussed Induction Probe

A seven-coil focussed electromagnetic probe that provides two simultaneous conductivity logs, corresponding to "medium" and "deep" radii of investigation into the formation. The probe offers more information than the single-spaced induction probe in porous, permeable formations where displacement of formation fluids by drilling mud creates an "invasion zone" with different electrical properties.

PRINCIPLE OF MEASUREMENT
An oscillating high-frequency magnetic field from a transmitter coil within the probe induces an alternating electrical current within the surrounding conductive formation. This current, in turn, induces voltages within receiver coils in the probe proportional to the formation conductivity. The transmitter-receiver spacings determine the depth of investigation of the measurements. Additional focussing coils minimise the contribution of the borehole signal.

   
FEATURES
Formation conductivity measurement in wet/dry boreholes or through plastic casing
Separate deep and medium penetrating measurements give information on invaded zone
Seven-coil focussed measurements almost eliminates borehole signal
PSD (phase-sensitive detector) discriminates between magnetic susceptibility and conductivity signals
Option of natural gamma for correlation
MEASUREMENTS
Deep formation conductivity
Shallow 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 between wells
Other Indication of hydrocarbons
OPERATING CONDITIONS
Borehole type open or plastic/grp cased, air/water-filled
Centralisation Fin stand-off recommended
SPECIFICATIONS
Diameter 38mm
Length 2.15m
Weight 8kg
Max. temperature 70ºC (extended range available)
Max. pressure 20MPa (extended range available)
Number of coils 7
Conductivity range 5 to 3000mS/m
Operating frequency 39kHz Effective TX-RX
Spacings ILM 50cm (20"), ILD 81cm (32")
Resolution 1mS/m
Natural-gamma detector 50mm x 25mm NaI(Tl) scintillation crystal (larger sizes available)
SALES INFORMATION
Probe
25 060 000 Dual focussed induction probe with field calibrator
25 061 000 includes natural gamma
Accessories
23 001 000 Fin stand-off
20 007 000 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