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Radioactivity logging memory tool APRK-3N


The tool has the following modifications by max operating temperature T max and upper value of borehole hydrostatic pressure Pmax: 
  T max =90 °C, Pmax= 80 MPa;
Designed to measure simultaneously water-filled porosity (volumetric moisture content) of formations by neutron-neutron thermal logging (NNLth) and exposure rate (ER) of natural gamma radiation. Counting rates by three channels of neutron logging, counting rates by two independent channels of gamma-ray logging and technological parameters (current real time, temperature inside the tool, supply voltage and triaxial accelerometer readings) are recorded while logging.

Used for logging of wells drilled with diameter from 120 to 350 mm, wells that have horizontal or nearly horizontal final section filled with any mud. The tool ends with Z-86 thread and is attached directly to the drilling tool.

 well section lithological identification;
 reservoir properties and rocks mineral composition identification.

The measuring equipment of compensated neutron-neutron logging, three-sonde – 3NNKt-24/43/59 (chamber for fast neutron encapsulated source (Pu+Be, with output of 5×106 up to 107 n/sec) . GR measuring equipment consists of two independent detectors (NaJ(Tl) or CsJ(Na) scintillation).


 Measured parameters Range Error
ER of natural gamma radiation 0÷250 mR/h ±15 %
Uranium equivalent mass fraction 0÷200×10-4 % ±(5+140/Ue )%
Water-filled porosity by NNLth 1÷40 % 4.2+2.3(40/phi-1)

 General specifications
Tool length, mm 3740 not more than
Tool diameter, mm 108 not more than
Tool weight, kg 120 not more than
Power supply, self-contained, V 12  
ÌMax operating temperature,0C 90 not more than
Max operating pressure, MPa 60 not more than
Borehole diameter, mm 120÷350  
Logging speed, m/ hr 800  
Operating time in memory mode,  hours in record mode 10 not less than
Records frequency, pollings per sec 2 (10 pollings per 
1 m)
Location on the drilling tool